Effect of Deficit Irrigation and Storage on Physicochemical Quality of Tomato (Lycopersicon esculentum Mill. Var. Pechtomech)

Deficit irrigation is a water saving strategy used to make economic use of water for agricultural activities in order to save water for other purposes. This water deficit may have some negative effects on the quality and postharvest life of the food produced. The aim of this study was to determine the effects of deficit irrigation and postharvest storage on some physicochemical qualities of tomatoes. Tomato fruits (Pectomech variety) cultivated under different irrigation treatments (100% ETc, 90% ETc, 80% ETc and 70% ETc) were harvested and analyzed for firmness, total soluble solids (TSS), titratable acidity (TA) and pH. Firmness was determined by a penetrometer, TSS by hand refractometer, TA by titrating the juice with a standard base (NaOH) and pH by pH meter. Results indicated that firmness, total soluble solids, titratable acidity increased with increasing deficit irrigation while pH decreased. However, these increases and decreases in the parameters with the various water applications were not significant. Titratable acidity of the tomato fruits decreased significantly (p<0.05) as storage progressed. Firmness of the fruits decreased while total soluble solids and pH increased with increasing storage period. Considering the percentage increases and decreases in the physicochemical qualities of the tomatoes in this study, it can be concluded that a 10% reduction in the amount or volume of water applied in the cultivation of the Pectomech tomato variety would produce tomato with optimum quality that would compensate for yield losses. Keywords: Deficit irrigation, firmness, Pectomech, titratable acidity, total soluble solids

Variation in ultrasonic frequency and time as pre-treatments to air-drying of carrot

Vegetable drying is an alternative method to curb post harvest decay of vegetables and a process to produce dried vegetables, which can be directly consumed or used as ingredients for the preparation of soups, stews, baby foods, cakes, puddings, and many other foods. In this study, the effect of ultrasound frequency and sonication time as pre-treatment prior to air drying at 70°C at an air velocity of 0.5 m/s, on carrot drying kinetics, flavour, colour, and non-enzymatic browning was investigated using a 3-level factorial response surface method. The result showed that an increase in sonication frequency and time did not significantly increase moisture diffusivity but in comparison with the control, water diffusivity increased after ultrasound application and the overall drying time was reduced. Application of the ultrasound pre-treatment in distilled water resulted in water gain and sugar loss, indicating that the ultrasonic pre-treatment can be an important step to produce low sugar content dried products. The brightness and redness to yellowness values of the ultrasonically pre-treated dried carrots were better than those without ultrasound application. In comparison with the flavour of the control, the ultrasound pre-treated samples recorded higher flavour response signals, indicating that the application of ultrasound improved the flavour of the dried carrot. The variation in sonication frequency and time did not significantly affect the non-enzymatic browning index of the dried products but were better than the control

Analiza wydajności systemu pośredniego chłodzenia wyparnego do przechowywania owoców mango na sawanach i w strefach przejściowych Ghany

Performance analysis of a 1.0 tonne desiccant evaporative cooling storage structure for mango fruits was studied. The study examined the effects of inlet air conditions and water flow rates through an absorber on the cooling performance of the system. The airflow rate was approximately 0.24 m3·s -1 and water flow rates through the absorber varied from 0 to 0.252 l·s -1 . The system produced approximately 7 kW of cooling at water supply rate of 0.252 l·s -1. A simple linear correlation was established for condition line slope from inlet to exiting air conditions for all the water flow rates. Lines of best fit resulted in correlation coefficient better than 0.96. The observed temperatures with a direct evaporative cooler, tested with freshly harvested mango fruits were found to be between 15.1°C and 23.4°C and relative humidity between 81.8% and 97.7%. Physiological weight loss and firmness assessments of the fruits were also conducted.Artykuł omawia analizę wydajności chłodni wyparnej o poj. 1,0 tony, wykorzystywanej do przechowywania owoców mango. Zbadano wpływ warunków wlotowych powietrza i szybkości przepływu wody przez pochłaniacz na wydajność chłodniczą systemu. Natężenie przepływu powietrza wynosiło około 0,24 m3·s-1 , a natężenie przepływu wody przez absorber wahało się od 0 do 0,252 l·s-1 . W tym czasie wyprodukowano około 7 kW chłodu przy przepływie wody wynoszącym 0,252 l·s -1 . Określono prostą korelację liniową nachylenia linii wykresu warunków, od wlotu do wylotu powietrza, dla wszystkich wielkości przepływu wody. Linie o najlepszym dopasowaniu dały współczynnik korelacji powyżej 0,96. Zaobserwowane temperatury chłodni wyparnej, sprawdzane na świeżo zebranych owocach mango, wynosiły od 15,1°C do 23,4°C, a wilgotność względna od 81,8% do 97,7 %. Dokonano również oceny fizjologicznej utraty masy i jędrności owoców

Benefits and costs of cultivating rice using biochar-inorganic fertilizer combinations

Biochar is a carbon rich material obtained by the incomplete combustion of biomass. Agronomically, biochar is used as a soil amendment, usually in combination with other amendments such as fertilizer or compost. For environmental purposes, biochar serves as a means of sequesting carbon, thus mitigating climate change. It also has remediating properties such as adsorbing contaminants from water and soils. In this study, different rates of rice straw biochar combined with various inorganic fertilizer rates were applied on rice fields. The field experiment was conducted in both the major season and minor season of the year 2018. The minor season cultivation had two fields: minor season main and minor season residual. The minor season residual field did not have biochar reapplied to it because it was to assess the residual effect of the biochar applied during the major season. The economic costs were computed from the cost involved in the activities of the rice production processes. Rice yield was harvested at maturity and the yield converted into revenue using prevailing selling price. Net Present Values (NPVs) and Benefit Cost Ratios (BCRs) were computed for each treatment. The results indicated that the use of biochar as soil amendment in rice production is costly during the first production cycle, however, its residual effect is able to yield benefits that outweigh the costs, thus making biochar usage profitable in the second cropping season. Generally, the major season (first cropping cycle) had low BCRs, ranging from 0.54 to 1.33 compared with those of the minor season residual fields (second cropping cycle), which were between 1.22 and 1.84. The minor season residual fields had NPVs that were generally higher (−724 to 2069) than those of the major season (−2757 to 1300)

Assessment of a mobile solar biomass hybrid dryer for insect disinfestation in dried maize grains: Presentation

Considerable losses of stored food grains occur through insect infestation in tropical countries because climatic conditions are conducive for insect activity throughout the year. Studies have shown that in order to kill stored grain insects of all life stages temperatures above 50°C are required. However, grain simply laid in the sun or placed in a solar dryer does not reach such high temperatures. This study describes the use of a 1 tonne batch capacity mobile solar biomass hybrid dryer for disinfestation of infested maize and prevention of F1 progeny emergence in stored maize grains. To assess the effect of temperature and exposure period on mortality of maize weevils, infested maize in experimental cages were exposed for 3 and 6 hours of thermal disinfestation treatment in the dryer. Comparing the heat generated in the dryer under hybrid mode operation where additional heat is generated by a biomass furnace in addition to solar, a mean temperature of 67°C was recorded compared to a mean ambient temperature of 36°C. Results showed that there was no significant difference (p < 0.05) in mortality of maize weevils during disinfestation treatment for 3 and 6-hour exposure periods. Mortality of 100% was obtained for samples disinfested in the highest tray (level 4) in the dryer. After 30 days of storage of disinfested maize grains, there was no emergence of F1 progeny from the maize grains exposed for 3 and 6 hours. Effect of ambient temperature and open sun exposure periods in the control set-up resulted in low mean percent mortality. Also, samples from the control set-up at both 3 and 6-hour exposure periods showed emergence of F1 progeny after storage. From this study, it can be concluded that an exposure period of 3 hours (or perhaps even less) in the solar biomass hybrid dryer could prevent damage by Sitophilus zeamais to stored maize grains after thermal disinfestation at a mean temperature of 67°C.Considerable losses of stored food grains occur through insect infestation in tropical countries because climatic conditions are conducive for insect activity throughout the year. Studies have shown that in order to kill stored grain insects of all life stages temperatures above 50°C are required. However, grain simply laid in the sun or placed in a solar dryer does not reach such high temperatures. This study describes the use of a 1 tonne batch capacity mobile solar biomass hybrid dryer for disinfestation of infested maize and prevention of F1 progeny emergence in stored maize grains. To assess the effect of temperature and exposure period on mortality of maize weevils, infested maize in experimental cages were exposed for 3 and 6 hours of thermal disinfestation treatment in the dryer. Comparing the heat generated in the dryer under hybrid mode operation where additional heat is generated by a biomass furnace in addition to solar, a mean temperature of 67°C was recorded compared to a mean ambient temperature of 36°C. Results showed that there was no significant difference (p < 0.05) in mortality of maize weevils during disinfestation treatment for 3 and 6-hour exposure periods. Mortality of 100% was obtained for samples disinfested in the highest tray (level 4) in the dryer. After 30 days of storage of disinfested maize grains, there was no emergence of F1 progeny from the maize grains exposed for 3 and 6 hours. Effect of ambient temperature and open sun exposure periods in the control set-up resulted in low mean percent mortality. Also, samples from the control set-up at both 3 and 6-hour exposure periods showed emergence of F1 progeny after storage. From this study, it can be concluded that an exposure period of 3 hours (or perhaps even less) in the solar biomass hybrid dryer could prevent damage by Sitophilus zeamais to stored maize grains after thermal disinfestation at a mean temperature of 67°C

Effects of Temperature and Variety on Rehydration Parameters and Solute Loss during Soaking of Omakwa and Abrohemaa Maize Varieties

This study was carried out to investigate the effects of soaking temperature and variety on the rehydration parameters and solute loss (essential minerals and vitamin C) of two maize varieties. Sun-dried kernels of the maize varieties (Omakwa and Abrohemaa) were soaked at four different water temperatures of 30oC, 40oC, 50oC and 60oC in a thermostatic water bath and the rehydration parameters determined. Temperature and variety were the two principal factors found to influence water uptake by the kernels. The highest rehydration ratio of 13.28 and 14.65 for Omakwa and Abrohemaa respectively occurred at the highest soaking temperature of 60oC. The quantitative analysis of solute loss (phosphorus, sodium, potassium and vitamin C) carried out reveals that large amounts of Potassium and vitamin C leached into the soaking water at higher water temperatures while residual amount of sodium saw an initial increase before decreasing to a low value as the temperature increases. For phosphorus, larger residual amounts were obtained at low to moderate soaking temperatures while a further increase in soaking temperature beyond 50oC resulted in a decrease. Soaking at temperatures of 40oC and 50oC were found to retain more nutrients hence moderate temperature of 40oC ≤X≤ 50oC may be considered for soaking of Omakwa and Abrohemaa maize varieties