Effects of indirect air cooling combined with direct evaporative cooling on the quality of stored tomato fruit

Abstract

A 53 m 3 solar-powered evaporative cooler for temporary storage of tomato fruit was developed to improve the shelf life of tomatoes under hot and humid climatic conditions. This study investigated the effect of indirect air-cooling combined with evaporative cooling (IAC+EC), maturity stage at harvesting and period of storage on the quality of tomatoes. The effect of total soluble solids, firmness, color, physiological weight loss (PWL), and marketability of tomatoes (star 9037) was investigated by monitoring the storage of green and pink maturity stage harvested fruit over 28 days under both IAC+EC and ambient conditions. The three factors had a significant effect (P < .001) on the overall quality of tomatoes. The tomatoes stored in the IAC+EC system were 18.9% firmer, maintained 10.5% lower concentration of sugars, increased the hue angle by 3%, had 6.31% lower PWL and were 24.8% more marketability than tomatoes stored under ambient conditions. The tomatoes harvested at the green stage were 20.2% firmer, had 6.6% lower total soluble content, increased the hue angle by 4.9%, had a 3.1% lower PWL, and were 11.6% more marketable than the pink harvested tomatoes. This study clearly demonstrated the efficacy of IAC+EC under sub-humid and hot conditions in improving the quality and marketability and increasing the shelf life of tomatoes by reducing the rate of ripening and utilization of sugar. Efectos de la refrigeración indirecta por aire combinada con refrigeración por evaporación directa en la calidad de tomates almacenados RESUMEN Para efectos del presente estudio se fabricó un enfriador por evaporación de 53 m 3 activado mediante energía solar, el cual se destinó al almacenamiento temporal de tomates, mejorando su vida útil en condiciones climáticas cálidas y húmedas. Al respecto, el estudio investigó el efecto del enfriamiento causado por aire indirecto combinado con el enfriamiento causado por evaporación (IAC+EC), la etapa de madurez de los tomates en el momento de la cosecha y el impacto del periodo de almacenamiento sobre la calidad de los tomates. Monitoreando el almacenamiento durante 28 días-bajo IAC+EC y condiciones ambientales-de tomates verdes y rosados cosechados en la etapa de madurez se investigaron: el efecto de los sólidos solubles totales, la firmeza, el color, su pérdida de peso fisiológica y la comerciabilidad de los tomates (star 9037). Se constató que los tres factores tuvieron un efecto significativo (P <.001) en la calidad general de los tomates. Los tomates almacenados en el sistema IAC+EC fueron 18.9% más firmes, exhibieron una concentración de azúcares 10.5% más baja, mostraron un aumento de 3% en el ángulo de tono, una pérdida de peso fisiológica (PWL) 6.31% más baja y eran 24.8% más comercializables que los tomates almacenados bajo condiciones ambientales. Los tomates cosechados en la etapa verde fueron 20.2% más firmes, tuvieron un contenido soluble total 6.6% más bajo, mostraron un aumento de 4.9% en el ángulo de tono, presentaron un PWL 3.1% más bajo y eran 11.6% más comercializabl...

Performance evaluation of an indirect air cooling system combined with evaporative cooling

“…The values of 85 > RH < 95 are ideally storage conditions for produce like avocados, bananas, cucumbers, mangoes, oranges, papaya, sweet potatoes and tomatoes [36]. The IAC þ EC system increased ambient RH from 47% to 87-93%, which is in agreement with [14] that obtained values of 75-88%. However, the result of average ambient RH ranging from 44 to 65% between 10h00 and 17h00 was below that recommended by [37] and hence this will reduce the shelf life of fresh FV storage.…”

“…This demonstrates that the use of IAC þ EC significantly increases the storage chamber RH and thus prolonging the shelf life of tomatoes and many other fresh produce. The results of incorporating a heat exchanger in this study indicate that the EC system increased the relative humidity of the air when extended to hot and sub-humid to humid conditions, indicating reduction in physiological weight loss from FV as evidenced by the working of [14].…”

“…It is therefore important to develop, evaluate the performance and determine the cooling efficiency of small-scale farming sized IAC þ EC system as there is dearth of information. This work is a continuation of the work reported by [14]. To adopt an IAC þ EC system, an energy source to power the heat exchanger (desiccation unit), fans and water pump for air and water circulation is required [15].…”

“…The array system consisted of a 3 string-3 series 330W solar modules with 44.80 V rated voltage and 8.69 A current, a 145 VDC-60 A (SANTAKUPS PC16-6015F) solar charge controller, 5 kW-60A (Sinowave, P11-LW5000NC48-C) inverter, 3 string-4 series 230 AH batteries. This translated to practical power output from the solar panels of 2 639 W against the design load for all electrical appliances of 2 310 W as determined by [14] in a parallel work to this manuscript.…”

Passive evaporative coolers for postharvest storage of fruit and vegetables: Where to best deploy them and how well do they perform

“…Active and passive cooler types exist, where active coolers apply forced airflow generation to evaporate water from a cooling medium. A lot of work has already been done on evaporative cooling (Anyanwu, 2004;Mittal et al, 2006;Dadhich et al, 2008;Getinet et al, 2008;Vanndy et al, 2008;Olosunde et al, 2016;Olosunde et al, 2009;Chinenye, 2011;Mogaji and Fapetu, 2011;Shitanda et al, 2011;Manuwa and Odey, 2012;Chinenye et al, 2013;Mogaji et al, 2013;Samira et al, 2013;Deoraj et al, 2015;Ogbuagu et al, 2016;Zakari et al, 2016;Alam et al, 2017;Ambuko et al, 2017;Korir et al, 2017;Poku et al, 2017;Nkolisa et al, 2018;Adekanye et al, 2019;Sibanda and Workneh, 2019;Abaranji et al, 2021;Patel et al, 2021;Raza et al, 2021;Sibanda and Seyoum Workneh, 2021). Based on this literature, postharvest storage us usually done using active (~50%) and passive (~30%) direct coolers.…”