Agronomía Mesoamericana

Microbiology of carrot, tomato and cabbage from organic and conventional agriculture in Costa Rica

Fiorella Castro-Urbina — 2023-04-27

Introduction. Interest in consuming fresh products such as vegetables has been increasing over the years. Different cultivation methods to produce vegetables such as carrots, tomatoes, and cabbages are available. Conventional and organic farming systems are the most common. Objective. To compare the microbiology of carrot, tomato and cabbage from farms with organic or conventional agricultural production systems in Costa Rica. Materials and methods. Sampling was carried out in Cartago, Heredia and Alajuela, Costa Rica, from September 2020 to November 2021, during the rainy season in all cases. Vegetables from model farms of carrot, tomato and cabbage, one of organic production and three of conventional production, were sampled. Microbial counts of total aerobic mesophilic, total coliforms, Escherichia coli, yeasts and molds, and the absence/presence of Listeria monocytogenes were determined. Results. Total aerobic, yeast and mold and total coliform counts for conventionally and organically grown carrots, cabbages, and tomatoes did not differ from each other. In the vegetables studied, E. coli counts were <1 log CFU/g and Listeria monocytogenes was absent. Presence of Listeria sp. in carrot samples from conventional cultivation was found in contrast to its absence in carrots from organic cultivation. Conclusions. L. monocytogenes was absent in the vegetables studied, which in general had acceptable microbial loads according to regulations and similar to studies reported worldwide. Under controlled conditions, when compared to those obtained from conventional production systems, it is possible to obtain vegetables from organic farming without detriment to their microbiological quality and with the derived benefits for the health of the consumer and the environment.

Agricultural experiments with repeated measures over time: analysis strategies comparison

Jorge Claudio Vargas-Rojas — 2023-04-27

Introduction. Several modeling techniques have been used to analyze experiments with repeated measures over time; however, some of these are no longer relevant. Objective. To compare four analysis strategies that are used to analyze agricultural experiments with evaluations over time. Materials and methods. Data from an experiment in which the effect of different nitrogen fertilizer sources on chlorophyll content in a forage grass at different harvest ages was used. These data were analyzed using four strategies: the area under the curve index (AUC), multivariate analysis of variance (MANOVA), random effect of the experimental unit, and temporal correlation modeling. The lasts two strategies were performed under the theory of mixed linear models; in these different models were fitted, all with the same fixed effects structure, but with different random effects, residual correlation structure, or residual variance structure. Using penalized likelihood criteria [Akaike information criterion (AIC) and Bayesian information criterion (BIC)], the best fitting model was chosen, with which inferences were made about the means of the significant fixed effects, and compared with the results obtained from the AUC and MANOVA strategies. Results. The best fitting mixed linear had a compound symmetry correlation structure and heteroscedastic variances. This model allowed for the analysis of the treatment × time interaction; on the other hand, both the MANOVA and the AUC allowed for the analysis of temporal trends of the treatments. Conclusion. The best fitting mixed linear model made it possible to select the best treatment based on the evaluation time. On the other hand, both the MANOVA and the AUC led to the selection of treatments that were not the best at all evaluation times.

Antioxidant substances in different phenological phases of Psidium guajava L.

Evelyn Del Carmen Pérez-Pérez — 2023-03-27

Introduction. There is worldwide interest in determining the content of plant-based antioxidant substances, and the relationship of the phenological phases of the plant with the production of secondary metabolites. Objective. To determine the effect of phenological phases on the content of antioxidant substances of guava (Psidium guajava L.). Materials and methods. A population sample of 10 % of guava plants from the germplasm bank of CESID-Frutícola y Apícola-CORPOZULIA, located in the municipality of Mara, Zulia state, Venezuela, was evaluated. The content of total phenols (FeT), total flavonoids (FlT), and antioxidant capacity (CA) were determined in dry leaves samples at different phenological phases of the plant, recorded from October 2012 to September 2013. Extraction of the FeT was performed by ultrasound with 0.5 g of dry sample and a methanol: water mixture (80:20 % v/v). For quantification by UV-VIS absorption spectrophotometry, gallic acid for FeT and catechin for FlT were used as standard. The AC was determined by the cation-radical ABTS▪+. Non-parametric statistics were used using SPSS statistical software. Results. The three phenological phases (flowering, fruiting, vegetative sprouting) occurred in guava plants, the reproductive phase prevailed with 38.99 % of flowers and fruits; with higher average presence of vegetative shoots that occurred during the rainy season and the alternation between flowers and fruits production. Intra-population variability was observed in the content of antioxidant substances, FeT content, compared to CA and FlT, was higher in fruiting and in the absence of precipitation. Conclusion. The phenological phases had an effect on the content of antioxidant substances of guava. The fruiting phase had the highest content of total phenols. The contents of total phenols and flavonoids were related to antioxidant capacity.

Non-compliance nutritional content of imported pet food in Costa Rica

André Cedeño-López — 2023-05-18

Introduction. The regulations that govern balanced pet food ensure the welfare of pets, public health, and consumer safety, making it valuable to verify the nutritional content declared on labels. Objective. To determine the compliance of the guaranteed analysis of 34 imported foods for dogs, cats, hamsters, rabbits, ornamental fish, and turtles and compare the results with the nutritional recommendations found in the literature. Materials and methods. During the months of August and December of 2018, food samples of dog (10), cat (10), ornamental fish (5), turtles (4), hamster (3), and rabbits (2) food were obtained by direct purchase at different points of sale in San José, Costa Rica. The content of moisture, crude protein (CP), ether extract (EE), crude fiber (CF), calcium, phosphorus, salt, and carbohydrates were analyzed. The average content, standard deviation, maximum and minimum value of each nutrient in each group of food were calculated according to the animal species. The individual and average values obtained were compared with the values declared on the label and the nutritional recommendations found in the literature. Results. The nutrients that presented non-compliances were: salt (27), calcium (16), and energy (14). Additionally, it was found that some foods did not declare the content of salt (14), calcium (9), and phosphorus (7). With respect to the minimum nutritional requirements, twenty-two samples presented deficiencies or excesses in at least one nutriment [carbohydrates (11) and ether extract (7)]. Conclusions. Imported balanced foods for dogs, cats, rabbits, hamsters, turtles, and ornamental fish presented non-compliances in the guaranteed content of CP, EE, CF, ME, Ca, P, and salt declared on the label. The nutritional composition of the evaluated foods limits compliance with the nutritional requirements of the animals, except for rabbits that do comply with the requirements.

50th anniversary of the Center for Research in Grains and Seeds (CIGRAS): History and contributions in research, teaching, and social work

María Viñas — 2022-09-06

SNP fingerprinting and farmer criteria for selection, multiplication, and traceability of cacao in Nicaragua

Melanie Bordeaux — 2023-05-25

Introduction. Genetic diversity, registration, and traceability of cacao planting material are the essential tripod to support its sustainable cultivation. In Nicaragua, cocoa planting material is mostly obtained from seeds, which leads to great variability in yield, bean quality, and tolerance to pests and diseases. Farmers, technical staff, development projects, and investors depend on a limited supply of elite trees as a reliable source of genetic material to support new cacao fronts and meet market quality standards. Therefore, the development of a national genetic improvement program and a planting material traceability system in Nicaragua are necessary to improve the sustainability of cacao cultivation. Objective. To evaluate the genetic resources on farms and provide information for future breeding programs, as well as to lay foundation for a national traceability and certification system. Materials and methods. Fourty-nine elite trees selected by farmers in the main producing regions in Nicaragua between 2018 and 2020 were sampled. Ninety-three SNP markers were used to characterize them and resolve their genetic origins. Results. The evaluated cacao trees had a narrow genetic background, mainly composed of hybrids with Amelonado (36 %), Criollo (17 %) and Iquitos (15 %) origins. A set of trees with high genetic diversity that could be incorporated into a selection and breeding program was identified. Conclusion. Fingerprinting with SNP markers was a useful tool for evaluating the genetic links of cultivated cacao and can be used for varietal identity test at the farm level. The study provided the basis for developing both a breeding program and a traceability system of cacao planting material in Nicaragua.

Bacterial coinfections on foliar blight and bulb rot in onion (Allium cepa L.)

Juan Carlos Jiménez-Acero — 2023-02-21

Introduction. The onion bulb (Allium cepa L.) is a cultivated vegetable characterized by its fleshy scales susceptible to phytopathogen attacks causing economic losses. The symptoms of foliar wilting, blighting, and rot of bulb can be caused by different genera and bacterial species that can co-infect the host, making it difficult to identify the causal agent. Objective. To evaluate the effect of bacterial co-infections on foliar wilt and bulb rot in onion. Materials and methods. The bacteria were isolated from onion plants with symptoms of leaf blight and bulb rot, from crops located in Choachí Cundinamarca, Colombia, collected in June 2018. Bacterial isolates were purified, identified, and inoculated individually and in a mixture on healthy onion leaves and bulbs. Six treatments per organ were evaluated: three with individual infections and three with co-infection. The lesion progress was measured in both organs for twelve days after inoculation. Results. Two bacterial species identified as Pantoea ananatis and Rahnella aquatilis were obtained from the foliar and bulb symptoms. In individual infections, the P. ananatis strain presented the highest virulence causing 34.29 % bulb damage, and 100 % leaf damage, while the R. aquatilis generated the lowest percentage of rotting in the bulb (8.87 %) and it did not produce wilt. In co-infections, the combination of P. ananatis and R. aquatilis produced the lowest percentages of bulb (15 %) and leaf (10 %) damage, associated with a decrease in the symptom’s expression. Conclusion. R. aquatilis acted as an antagonistic organism of P. ananatis and causes a delay in the development of foliar wilt and bulb rot symptoms in onion.

olletotrichum species associated with anthracnose in orange (Citrus sinensis (L.) Osb.) and its in vitro control with fungicides

María José Guillén-Carvajal — 2023-02-13

Introduction. Orange (Citrus sinensis (L.) Osb.) cultivation is one of the most important worldwide. Among the main limitations in its production is the fall of flowers caused by Colletotrichum. Objective. To determine the species of Colletotrichum associated with anthracnose in orange and to estimate the in vitro effectiveness of four fungicides on its control. Materials and methods. This study was carried out between June 2021 and February 2022. Six fungal isolates, obtained from orange floral tissues, were identified via polymerase chain reaction (PCR). The efficacy of the fungicides tebuconazole, pyraclostrobin, difenoconazole, and ferbam on two Colletotrichum isolates was evaluated. Two tests were carried out to determine the degree of inhibition of mycelial growth and the percentage of effectiveness of each fungicide. Results. Colletotrichum abscissum was identified on petals with symptoms and Colletotrichum gloeosporioides on calyxes. The effectiveness of the doses used of the fungicides tebuconazole and difenoconazole was verified by presenting inhibition of mycelial growth from a tenth of the commercial dose evaluated. Pyraclostrobin showed little control over both isolates. Ferbam did not present an efficient control in any of the doses evaluated in both strains. Conclusion. The fungi associated with anthracnose in orange, on the farm studied, were C. abscissum, present on petals with initial and advanced symptoms, and C. gloeosporioides present on persistent calyxes. The effectiveness of the fungicides evaluated was higher for triazoles, tebuconazole, and difenoconazole, in that order. Pyraclostrobin showed a poor control on both isolates. Ferbam was not effective in in vitro tests.

The effect of processing and storage on Klanceng honey (Tetragonula laeviceps)

Budianto Budianto — 2023-03-27

Introduction. Klanceng honey (Tetragonula laeviceps) is in great demand because of its benefits. There is no information on the expiration date of the Klanceng honey. Objective. To predict the shelf life of Klanceng honey by evaluating the effect of heating (40 ºC / 48 h and 70 ºC / 7 h) and storage for two years. Materials and methods. The analysis was carried out three times (2020, 2021, and 2022) at the National Innovation Research Agency Laboratory, Jakarta, Indonesia. Samples of Klanceng honey (Tetragonula laeviceps) were taken from a bee farm in Magetan, East Java, Indonesia. The sample (5 kg) was divided into 3: without heating process (UT), heating at 40 ºC / 48 h (T1), and heating at 70 ºC / 7 h (T2). Then analyzed the activity of HMF, diastase, invertase, acid phosphatase (AP), glucose oxidase (GO), DPPH, honey color, and phenolic at 0, 12 and 24-months. Results. The results showed that short heating at high temperature (70 ºC / 7 h) had a greater impact on decreasing enzyme activity compared to prolonged heating at low temperature (40 ºC / 48 h). Storage had a major impact on the increase of 5-hydroxymethyl (furan)-2-carbaldehyde (HMF) compared to the heating process. During storage (24-months) the HMF value exceeded the maximum limit. Conclusions. The HMF value (55.33 ± 0.57 mg/kg) exceeded the maximum allowable limit (max 40 ppm), this was due to the significant effect of heating on T2 and the storage process. The shelf life of Klanceng honey was two years, as long as it was not heated to high temperatures (70 ºC).

Integrated management of yellow rust caused by Puccinia striiformis f. sp. tritici in wheat

M. Lavilla — 2023-04-25

Introduction. Yellow rust caused by Puccinia striiformis f. sp. tritici, is currently the main disease of wheat (Triticum aestivum) in the north of the province of Buenos Aires, Argentina. It has caused yield losses close to 20 %. Objective. To evaluate the effect of different agronomic management systems on wheat yield and incidence of yellow rust. Materials and methods. The trial was carried out in the town of Pergamino, Buenos Aires, Argentina, during the years 2019, 2020, and 2021. The experimental design was in subdivided plots, the largest plot was with and without cover crop, the subplot was agronomic management, and the sub-subplot the application was foliar fungicide at different phenological stages of the wheat crop. Results. With the use of foliar fungicides in stages close to stem elongation and the use of a cultivar resistant to the disease produced a reduction in the area under the disease progress curve (AUCPE) by 62.50 %, which translated into significant grain yield increases of 29.52 %. Foliar fungicide application resulted in a 16.94 % increase in wheat yield. The implementation of a sustainable integrated management system generated yield increases of 29.52 %. Conclusions. The use of a resistant cultivar and the application of a foliar fungicide at early stages and with low levels of the disease, significantly reduced the AUCPE of yellow rust and increased the wheat yield in experimental plots.

Detection of Duponchelia fovealis Zeller with pheromones in strawberry farms of Costa Rica

Francisco Gonzalez-Fuentes — 2023-02-13

Introduction. Duponchelia fovealis Z. is a pest of production crops in Europe and in the United States. It has recently been detected in strawberry production in Brazil, Mexico, and in a farm in the Vásquez de Coronado canton, San José, Costa Rica. Objective. To determine the presence and distribution of Duponchelia fovealis Z. in strawberry farms in Costa Rica. Materials and methods. During the dry seasons of 2020-2021 and 2021- 2022, traps baited with the D. fovealis pheromone were placed in the initially reported farm in Vásquez de Coronado and in six other farms located in the main strawberry regions of Costa Rica: La Cima of Dota, Llano Grande, Poás, and Vara Blanca. Results. The monitoring showed that the highest populations were established in the Vásquez de Coronado farm, while occasional captures were obtained in farms such as La Cima of Dota in San José and two in Llano Grande in Cartago. Conclusions. The presence of D. fovealis Z. in Costa Rica was determined, with limited distribution. Given this, an analysis of the risk of the pest and the implementation of measures to reduce the insect’s dispersal are suggested.

Substrate and spatial planting pattern on the productivity of clonal mini gardens of Tectona grandis Linn. F

Arantxa Rodríguez-Solís — 2023-03-07

Introduction. Tectona grandis is the species with the largest planted area in Costa Rica, due to the high prices in the international market. The production of plants for reforestation has been technified in the country and is currently being developed based on protected environment technologies, which increase productivity, reduce operating costs, and offer planting material throughout the year. Objective. To evaluate the effect of two substrates and five planting densities on the productivity of clonal mini-gardens of Tectona grandis in a protected environment. Materials and methods. Four readily available inert substrates were characterized by granulometry and moisture retention analysis, from which stone dust was selected as the optimum substrate. An experimental trial with a 2x5 factorial design was established in San Carlos, Costa Rica to evaluate two substrates (stone dust alone and with 25 % charcoal) and five planting densities (cm) of 10x10, 10x5, 7x5, 10x10 with two plants per hole and 10x10 with one plant in the middle. Each density had four clones as a replicate effect. The trial was evaluated during five continuous production cycles from January to September 2021. Results. The use of stone dust as substrate, without charcoal, recorded the highest productivity at a lower cost. The spatial planting arrangement of 10x10 cm with one plant in the middle (n=145 plants/m²), recorded the highest shoot production per mother plant (1.16). The 7x5 cm arrangement increased productivity by up to 206 shoots m²/month. Conclusion. The change in planting density of the clonal mini-garden, in a first stage to 10x10cm with an additional plant in the center, resulted in a high impact on productivity (74 %), greater efficiency in the use of space, and a better gradual change in the operating system.

Refreshing whey drink with the addition of rice flour and orange flavor

Ana Maritza Colominas-Aspuro — 2023-03-10

Introduction. Whey is the residual liquid product of the manufacture of cheese with useful nutritional value. It contains 95 % of the lactose, 25 % of the proteins and 8 % of fat of the total milk components. Objective. To elaborate a refreshing whey drink with the addition of rice flour and orange concentrate. Materials and methods. The experimental work was realized at Food Department laboratories belongs to Pharmacy and Foods Institute from Universidad de La Habana-Cuba, between January and May 2021. The raw materials: whey, rice flower, and orange concentrated juice were characterized. A mix design was applied using Design–expert version 8.0 program to get the better formulation (combination of ingredients). The independent variables in percentage were: whey (79.95 to 84.15), concentrated orange juice (7 to 11), and guar gum stabilizer (from 0.1 to 0.3), and as response variables, acceptability and stability of the obtained drink. The best combination of ingredients was evaluated by a panel of judges based on the intensity of the odor, orange flavor, and consistency, using the attibutes “light”, “moderate” and “marked”. Results. The best formulation was composed of whey (84.15 %), orange concentrate (7 %), refined sugar (5 %), rice flour (3.75 %), and guar gum stabilizer (0.1 %). The sensorial acceptability criteria given by the training judges was “I like it”. Regarding the intensity of the orange smell, the whey beverage received a balanced criteria between the “light” and “moderate” ratings and the consistency was qualified as “light”. Conclusions. All formulations tested showed good stability and adequate sensory acceptability. The best combination showed no phase separation at 24 hours after processing and was characterized by twenty tasters.

Semen analysis in precision farming in the 21st century

Carles Soler — 2023-01-30

Introduction. Assisted reproduction of animals traces its origins in the domestication of livestock species useful to humans. The consequent artificial selection processes allowed the development of biotechnological techniques that contributed to the improvement of animal production capacities. Objective. To contextualize the seminal analysis in precision farming in the 21st century. Development. The visualization of spermatozoa under the microscope can be considered as the first step in the advent of reproductive biotechnology and the basis for the development of assisted reproductive techniques. With the improvement of microscopy methods, it was possible to characterize male gametes, which meant a significant advance in artificial insemination technology. The turning point marked by the development of sperm conservation techniques implied a substantive change in the development of these technologies in livestock species, either with cryopreserved or refrigerated semen. These methods are of high value in the case of threatened species since germplasm banks can be created for genetic conservation and rescue of species at risk of extinction. Semen analysis has been developed alongside with assisted reproduction techniques and today it is considered a relevant technique in animal reproduction biotechnology, which has been perfected through the advancement of science and technology, optical physics, and computing. Conclusion. Seminal analysis has undergone a paradigm shift by rejecting obsolete techniques of subjective evaluation of semen quality and adopting objective methods of semen evaluation, through the analysis of large volumes of data and motility, kinematics, morphometrics, morphological, and DNA fragmentation variables, which allow a better characterization of the ejaculates of breeders in artificial insemination centers.

Physicochemical and sensory characteristics of a caprine milk caramel with the inclusion of amaretto

Pamela Malavassi-Conejo — 2023-03-16

Introduction. Worldwide, bovine dairy products are prevalent, so there is a need for studies focused on less traditional milk, such as goat milk. Objective. To evaluate the effect of two levels of inclusion of amaretto on the physicochemical and sensory characteristics of a goat milk caramel. Materials and methods. Between January and September 2017, at the Universidad de Costa Rica, milk caramels were made with two proportions (6 % and 9 %) of amaretto, which were selected using two focus groups, pH, Brix degrees, aw, texture, color, and sensory liking were evaluated. Results. The milk caramels with inclusion of 6 % and 9 % amaretto obtained the following characteristics respectively: 71.8 and 70.8 ºBrix, pH= 6.8 and 6.9, aw=0.8, hardness= 1.3 and 0.3, adhesiveness= 0.75 and 6.0, elasticity= 23.0 and 21.0, L*= 33.0 and 33.4, a*= 11.3 and 11.4, b*= 26.2, c*= 28.5 and 28.6, h*= 66.7 and 66.4, with an average liking of 7.3 and 7.7, and an average purchase intention of 6.9 and 7.2. The cluster analysis generated three groups of people: G1 = 25.5 % with a mean liking of 4.7 and 6.2 for the 6 % and 9 % formulations, respectively; G2 = 19.6 % with a mean liking of 8.5 and 5.5 for the 6 % and 9 % formulations, respectively; and G3 = 54.9 % with a mean liking of 8.2 and 9.1 for the 6 % and 9 % formulations, respectively. Conclusions. The inclusion of amaretto in the goat milk caramel turned out to be the product with the best profile. No significant differences were observed between the two liquor inclusion levels. The results suggest that both products had appropriate technical characteristics and taste.

Traceability in the agricultural sector: A review for the period 2017 – 2022

Andrés Mauricio Hualpa Zúñiga — 2023-02-08

Introduction. Traceability is regarded in business systems as a monitoring and control tool that is centered on measuring and gathering data for efficient resource allocation. The agricultural sector is no stranger to this practice because, like other industrial systems, it integrates control needs at the level of cultivation, supply of inputs, transformation, transportation, and marketing of products. Objective. To identify objects and scopes of monitoring, analysis units, and adoption of traceability trends in the agricultural supply chain, in order to reference the development of recent studies and publications that integrate this control function in this sector. Development. The applied methodology was developed through the search, selection, and analysis of articles in scientific repositories such as Science Direct and AGRIS, to identify trends in agricultural traceability in the years 2017 to 2022. Application and integration trends of traceability systems were recognized in the agricultural sector around different approaches, including digitization and information security, measurement of agricultural productivity and environmental impact mainly within the concept of sustainability. Lines of research are presented in its conclusions, as well as the knowledge gaps for future work. Conclusions. The results of the review in the last six years frame traceability trends mainly in the digital monitoring of cultivation processes, the measurement of productivity, and the environmental impact. The degree of direct intervention in the producer represents the highest proportion in the category of the logistic scope of traceability. Therefore, it is recommended in the future the development of traceability systems that monitor productivity, environmental, and social impact indicators in a convergent manner, as well as the integrated participations of actors in the agricultural sector, including producers, technical advisors, and government entities.

Autochthonous microorganisms as an alternative for the biofertilization of Glycine max (L.) Merrill

Wilson Geobel Ceiro Catasú — 2023-02-24

Introduction. Soybean (Glycine max (L.) Merrill) has economic and nutritional importance due to its protein levels and vegetable oil content of biological quality, necessary for human and animal feed. The microbial alternatives for biofertilization of this crop would represent an option for its production with low inputs in tropical conditions. Objective. To evaluate the effect of autochthonous microorganisms (MA) as an alternative for biofertilization of G. max under low-input production conditions. Materials and methods. The experiment was established in a farm located in the town of El Coco, Yara, Granma, Cuba, on a Carbonated Fluffy Brown soil, during the year 2021. Certified G. max cv. Incasoy-27 seeds were used. Sowing was carried out in spring at a distance of 0.70 m x 0.04 m. Three doses of MA (12, 24, and 36 L ha^-1) and an absolute control where used. Variables of growth, yield, and their components were evaluated. A randomized block design was used. Data were processed by ANOVA, linear regression, correlation, and principal component analysis. Results. The MA biostimulated the growth of G. max in a range of 12 % and 24 %, while the yield was favored between 16 % and 44 %. Pearson’s correlation analysis indicated that the seeds mass per plant and number of pods per plant were the variables most strongly interrelated with yield. Conclusion. The inclusion of MA achieved a biostimulation of plants length growth of G. max cv. Incasoy-27 compared to the control and the agricultural yield was enhanced.

Physico-chemical and sensory characterization of two rice (Oryza sativa) varieties during aging process

Adriana Araya-Morice — 2022-10-25

Introduction. Once harvested, paddy rice is stored in aerated silos for temperature control, which is known as rice aging. During aging, physicochemical, and physiological changes occur in the rice grain, these changes affect its culinary quality. Objective. To determine the effect of aging time on the physicochemical and sensory characteristics of two rice varieties. Materials and methods. This study was carried out in Agrifood Science Faculty Laboratories of the Universidad de Costa Rica, between September 2018 and March 2019. The two rice varieties studied were grown in Osa, Puntarenas. The first cv. Lazarroz FL, indica type, and the second cv. UCR-168-10, aromatic type were stored for 4.5 months. During storage, total starch, resistant starch, amylose, moisture, protein, was determined, and sensory attributes were evaluated with a trained sensory panel. Results. The two rice varieties studied don’t show significant differences during 4.5 months of storage in moisture, total starch, and resistant starch. Amylose content showed variation without a clear trend. Protein content was reduced during aging until 2,5 months of storage. According to the sensory test, attributes such as integral flavor and stickiness did not show significant differences throughout the study, while the remaining parameters did, either over time or between varieties. Cooked rice appearance showed an improvement up to 2,5 months aging for the two varieties. Whiteness of rice increased for both varieties during aging. Conclusion. Storing rice for 2,5 months achieved the desired changes in protein and sensory attributes for the rice varieties evaluated.

Quantification of the percentage of total broken grain in rice (Oryza sativa L.) by digital image analysis

Luis Arley Zúñiga Picado — 2022-11-30

Introduction. Digital image analysis (DIA) can be used to evaluate the quality parameters of rice grains, such as the percentage of whole grain. Objective. To quantify percentage of total broken grain by means of digital image analysis (DIA) applied to the quantification of rice (Oryza sativa L.) quality. Materials and methods. The present work was developed in facilities of the Centro para Investigaciones en Granos y Semillas (CIGRAS) of the Universidad de Costa Rica (UCR), Costa Rica, in 2021. The work was carried out with commercial rice samples. A sample plate was developed to facilitate the arrangement of the grains and to acquire the digital images. The length parameters established in the technical regulation of Costa Rica RTCR 202:1998 were used to quantify the percentages of small broken, broken grains, and whole grains, which were quantified conventionally and by means of digital images. The DIA included the segmentation and binarization process of the objects (small broken, broken grains, and whole grain) to quantify their areas and catalog the digitally identified elements in weight values. Results. It was possible to quantified the percentage of small broken and broken grain with DIA. The correlation between the variables quantified by DIA and those evaluated conventionally was greater than 0.93 for the small broken property and 0.98 for broken grain. Conventional analysis requires 1 to 2 hours to determine the percentage of total broken grain and other quality properties in each rice sample. The digital analysis requires 7 to 23 minutes per sample plate to analyze all the properties evaluated (small broken and broken grain). Conclusions. The digital analysis method applied allowed to determine the total broken grain properties in samples composed of hundreds of grains.

Morphology and viability test optimization in seeds of Passiflora spp. from Costa Rica

Elizabeth Vega-Corrales — 2022-10-14

Introduction. In Costa Rica there are 51 native species of passion fruit plants that have commercial potential due to their phytochemical characteristics. In Passiflora the seminal characteristics can be used to taxonomically classify the genus species. The identification of plant material and the development of methodologies that enable quality assessment is essential for propagation, production, and conservation. Objective. To characterize Passiflora biflora and Passiflora adenopoda seeds based on their morphology and to optimize the protocol for determining their viability by means of the tetrazolium test. Materials and methods. Morphological characterization and viability trials were carried out in 2022, at the Centro de Investigaciones en Granos y Semillas (CIGRAS), Universidad de Costa Rica. Twelve external morphological characters and the internal structures of P. biflora and P. adenopoda were characterized. For the optimization of the tetrazolium test protocol, the effect of two types of cutting (longitudinal and angular), two concentrations of tetrazolium salt (0.5 % and 1 %), three temperatures (30, 35, and 40 ºC), and four incubation times (3, 6, 12, and 24 h) were assessed. Results. The morphological characters evaluated allowed the seeds to be classified as P. biflora and P. adenopoda. By using 1 % tetrazolium salt, a longitudinal cut, a temperature of 40 ºC, and an incubation time of 3 h, similar viability percentage was obtained (90 % in P. biflora and 91 % in P. adenopoda), and a staining of the same quality, as that obtained with the international standardized method. Conclusions. The seminal characteristics assessed allowed the classification of the analyzed seeds as P. biflora and P. adenopoda. In addition, the tetrazolium test protocol was optimized by reducing the incubation time from 24 to 3 hours.

Physiological seed quality of carrot (Daucus carota L.) assessed by vigor testing

Edgar Jesús Vindas Quesada — 2022-10-19

Introduction. In carrot cultivation direct sowing is practiced because the seedling cannot resist the stress of transplanting. It is essential to use seeds that germinate in a maximum of seven days and uniformly. Seeds vigor is associated with yield performance in the field and, at the international level there are different test to measure it. However, in carrot, the methodologies are still scarce and are not standardized. Objective. To determine the physiological quality in seeds of two varieties of carrot (Daucus carota L.) by mean of vigor tests. Materials and methods. This research was carried out at the Centro para Investigaciones en Granos y Semillas (CIGRAS) of the Universidad de Costa Rica in 2018. Seeds of Bangor and Triunfo varieties with moisture percentages of 7 %, 10 %, and 13 % were used. The vigor tests used were the following: radicle protrusion, first germination count (seven days), accelerated aging, electrical conductivity, and the germination analysis by digital images. Pearson’s correlation analyses were performed between the variables studied. Results. Significant correlation coefficients (Pearson’s r) were observed for electrical conductivity with variables obtained from the image analysis: t10 (r=0.83), t50 (r=0.87), and the area under the curve (r=-0.72). Trough the electrical conductivity test, it was determined that the Bangor lot had greater vigor than the Triunfo lot (Tukey, p≤0.05). Conclusions. The analysis of digital images and the electrical conductivity tests allowed measuring the vigor in seed lots of Bangor and Triunfo varieties, and complementing them with germination results to determine their physiological quality.

Egg quality and productive performance of ISA Brown laying hens with grazing access

Rodolfo WingChing-Jones — 2023-02-06

Introduction. Egg production systems are critical to food security. Concerns about animal welfare are increasing the interest in egg production systems with access to grazing. Objective. To describe the productive performances, morphological characteristics, and nutritional quality of the eggs from laying hens of the Isa Brown genetic line in a floor system with access to grazing. Materials and Methods. The research was carried out between July 2018 and January 2020 in the central canton of Turrialba, Cartago, Costa Rica, with hens of the Isa Brown genetic line with access to grazing. Productive performances were compared with the standard of the genetic line. External and internal morphological variables of the egg were evaluated and its nutritional content (dry matter, crude protein, ethereal extract, ash, calcium, phosphorus, saturated fatty acids (SFA), monounsaturated (MUFA), and polyunsaturated (PUFA) was characterized in hens of different ages. Results. The productive performances was not different from the genetic standard. The increase in bird age had a statistically significant influence on the increase in egg and shell weight, and the decrease in morphological index. Nutritional analysis indicated that increasing hen age decreased the dry matter content and the concentration of SFA and MUFA in the egg. The PUFA/SFA ratio of the eggs was higher than 0.45, regardless of the age of the laying hen. Conclusion. The productive indicators of the hens with access to grazing did not differ from ISA Brown genetic line standards for alternative systems. Egg weight, yolk index, Haugh units, and morphology index varied with the age of the hen.

Phenological observations, oil characteristics and equilibrium isotherm of Myroxylon peruiferum seeds (Fabaceae)

Diego Aguilar-Sandí — 2022-11-29

Introduction. Phenological information on Myroxylon peruiferum in Costa Rica is scarce. In addition, the characteristics of the oil and the equilibrium isotherm are unknown. The knowledge generated in this field will allow proper seed management and generate oil prospecting options. Objectives. (i) To document a flowering and fruiting event of a single M. peruiferum tree. (ii) To determine the characteristics of the fruit and seed oil. (iii) To generate a water absorption/de-absorption isotherm. Materials and methods. From March to May 2021, the flowering and fruiting of M. peruiferum tree was documented in Montes de Oca, San Jose, Costa Rica. Mature fruits were collected between June and July. The oil content of fruits and seeds was characterized separately. A water absorption/de-absorption isotherm was elaborated, with which the fit of the Cromarty equation was tested. Results. The flowering, fruiting, and dispersal period lasted five months. These phenophases occurred simultaneously. Oleic acid was the main fatty acid. There was a significant correlation between the percentages of fatty acid in the fruit and seed oil, and between the contents of saturated, monounsaturated, and polyunsaturated fatty acids. The oil is yellow, moderately intense, and luminous. As relative humidity increased, seed moisture content also increased. The linear relationship between the actual values and those obtained using the Cromarty equation was R²= 0.93. Conclusion. Mature fruit can be harvested between March and August, and be used for germination, propagation and oil prospecting studies. Once the relationship between relative humidity and seed moisture content is established, studies on seed storage and viability loss can be developed.

Comparison of fecal near-infrared with conventional methods to estimate intake and digestibility in sheep

Diana Parra-Forero — 2023-02-22

Introduction. Intake and digestibility are parameters that define the quality of a forage; however, they are difficult and expensive to estimate. Near infrared spectroscopy technology applied to feces (NIRSf) is an alternative to conventional reference methods to estimate dry matter voluntary intake (DMVI) and digestibility (DMD) in sheep. Objective. To compare NIRSf technology with conventional methods for estimation of DMVI and DMD in confinement sheep. Materials and methods. Six bioassays were carried out at the Tibaitata research center, Cundinamarca, Colombia, during 2019 and 2021 with five sheep (LW 58.28±11 kg) to estimate DMVI and DMD by three methods: gravimetry, markers and NIRSf. The animals were fed six diets contrasting in their nutritional value. Forage and feces samples were collected, dried, and ground for subsequent chemical and spectral analysis. Results. The estimation of DMVI and DMD was different (p<0.001) in the six evaluated feeding regimenes, where the DMVIMW ranged from 37.54 to 82.58 g/kg LW0.75, and the DMD ranged from 36.32 to 58.81 %. In the comparison of the estimation of DMVI and DMD by the referent method (gravimetric) with marker and NIRSf methods, shows that the NIRSf method presented a better adjustment compared to the marker method, presenting less root mean square error value (-1.53 and -1.75, respectively), lower mean absolute error (-3.01 and -0.5, respectively), and higher determination coefficient (+0.09 and +0.28, respectively). Conclusion. The estimation of the DMVI and the DMD by means of the NIRSf equations presented a better fit compared to the marker method, however, it is necessary to improve the accuracy of the calibrations using feces samples from animals under different productive contexts.

Bioactive compounds in cheeses: biosynthesis, biological activity, and contribution of lactic acid bacteria

Joel López-Mendoza — 2023-03-06

Introduction. Since 1990, there has been an increase in the rate of diseases associated with unhealthy diets and sedentary lifestyles, whose care is a challenge for health systems. This has aroused interest in functional foods, i.e., those that in addition to providing macro and micronutrients, provide substances that have a physiological effect on the body, which translates into improving the health of those who ingest them. Generically, these compounds are known as bioactives. Objective. To review the main bioactive substances reported in cheeses, as well as the role of microorganisms in their production and the biosynthetic routes of the main compounds. Development. Milk and its derivatives are food products consumed around the world and show a constant increase in their production and consumption. This market trend is due to its flavor and nutritional value. One of the most demanded dairy products in the world are cheeses. They are a source of substances such as peptides, fatty acids, vitamins, bacteriocins, organic acids, gamma aminobutyric acid, etc. all with important biological activity. Conclusion. The presence, quantity, and availability of the bioactive compounds present in the cheeses differ, as a result of the type of milk used for its elaboration, the type of microorganism used, either as starter or secondary culture, as well as the technological process employed.

Fast seed histology protocols: Benzene derivatives-free vs xylene-dependent

M. Benavides-Acevedo — 2022-10-05

Introduction. Seeds are complex structures that allow the biological and crop propagation of plants. Seed histology can be used for teaching, researching, and for pathological diagnostic. Histology protocols are commonly divided into 5 different stages: fixation, processing, cutting, staining, and mounting. Xylene is a dangerous reagent used during the processing, staining, and mounting of histological specimens that can contaminate the environment and is toxic for users. Objective. To compare two new protocols for seed histology accelerated with microwave, tested on seeds of economic importance species. Materials and methods. The experiments were done between January and May of 2022 at the Centro de Investigaciones en Granos y Semillas (CIGRAS) of the Universidad de Costa Rica. The compared protocols were: a benzene derivatives-free (BDF) and a xylene-dependent (XD). Seeds of Carica papaya L. (Caricaceae) var. Pococí, Coffea arabica L. (Rubiaceae) var. Obata, Glycine max L. (Fabaceae) var. CIGRAS-06, Phaseolus vulgaris L. (Fabaceae) var. Tayni, Oryza sativa L. (Poaceae) var. Lazarroz FL, and Zea mays L. (Poaceae) var. EJN-2 were used. Three technical replicates of five seeds of each species were tested with the XD and BDF protocols, on different days each replicate. Results. The photomicrographs obtained with both protocols showed that the samples maintained the morphology integrity of embryo, endosperm or cotyledons, and other seed structures. BDF and XD protocols produced seed histology slides and microphotographs. PAS-Coomassie Blue staining made a good differentiation of carbohydrates and proteins. Fastness of both protocols is a benefit compared with other protocols for plant histology that can take several days or even weeks. Conclusions. The BDF and XD protocols were suitable for seed histology analysis of bean, coffee, maize, papaya, and soybean, slides were obtained in less than 5 hours. BDF protocol is the first for plant tissue processing that does not use benzene derivatives and that uses paraffin as embedding medium.