Development of a controlled atmosphere (CA) plant and shelf-life of fresh tomatoes at different storage conditions were studied in this research. The controlled chamber (4.5' × 4.5' × 4.5') with supplement of 1% L-ascorbic acid as antioxidant source was constructed using locally available materials. Fresh tomatoes were kept with wrapping by low density polyethylene under refrigerated and CA storage conditions. The maximum shelf-life of fresh tomato was 42 days under CA condition and followed by 35 days in refrigeration condition. Though initial cost of controlled atmosphere was high but it resulted in maximum shelf life of tomato. However, CA condition retained the physiological changes namely, color change, TSS, and weight loss of fresh tomatoes than that of stored in refrigerated condition. From nutritional point of view, it was concluded that developed CA plant could be used to extend the shelf-life of fresh tomatoes with minimum physico-chemical changes throughout the storage period.
Tomato is one of the most freshly consumed climacteric fruits, playing significant role in human nutrition for its vitamins, minerals, lycopene, β-Carotene and other bioactive constituents [
Post-harvest loss of climacteric fruits and vegetables is directly related to post-harvest operations. Again, mechanical damage, inadequate storage system, rough handling and improper transportation system are also associated with post-harvest loss of fresh fruits [
Several studies have been carried out to extend the shelf-life of tomato including use of permitted chemicals, inhibition or slowdown of respiration by low temperature, modified or controlled atmosphere [
Estimation says that postharvest loss of tomato in developing countries is almost 20% - 25% [
However, there is no research work regarding controlled atmosphere for storage of fresh tomato in Bangladesh. This research work was designed to study the storage performance of tomatoes stored at different conditions and develop an economical controlled atmosphere storage system for tomato.
The dimensions of the storage chamber were selected 4.5 × 4.5 × 4.5 ft by making similarities with the experiment of CA storage for bananas [
The air purifier chamber was made by timber (2' × 1" × 2') having dimensions 2 × 2 × 2 ft. This dimension was fixed with respect to storage chamber. The two chambers were joined by PVC pipe of 6 inch dia. And two fans of dia. 12" and 8" were also used at both the inlet and outlet sides of the storage chamber (
The basic principle of preservation of fresh fruits and vegetables in the CA is maintaining higher the amount CO2 and lower amount O2 than normal composition of air. Optimum storage temperature and RH for the desired product were also maintained. For the sake of above operating principle, an air flow of 1 - 1.5 cfm/min/btu should be maintained and the chemicals or such arrangement is required for purifying the circulating air and also closed it for leak proof (
Fresh and fully mature tomatoes were harvested manually from the research field of Hajee Mohammad Danesh Science and Technology University, Dinajpur. Harvested tomatoes were then sorted out to get almost similar tomatoes for further use as raw material in this research.
Sorted tomatoes were stored in two different storage conditions namely, refrigeration and controlled atmosphere condition. In refrigerated condition, tomatoes were weighed and kept in the refrigerator with low density polyethylene bags. In controlled atmosphere plant, tomatoes were kept at temperature of 20˚C with RH of 75% - 80%. Antioxidant in the rate of 1% of product weight was applied in the wooden chamber in perforated bag and the air flow was maintained 1 - 1.5 cfm/min/Btu.
Degree of maturity was measured with color change where color was measured by comparing with color chart and scored them with numeric value. Weight loss of tomato was calculated by differences between initial weight and final weight divided by initial weight at three days interval of storage period. Total soluble solids of tomato was measured using refractometer according to standard method of AOAC [
Obtained data from physico-chemical analysis were statistically analyzed by one way ANOVA using SPSS program (version 20). DMRT was applied to differentiate the mean value significantly with a significance level of 5%.
The shelf life of tomatoes varied under different storage conditions. The higher shelf life of tomatoes was observed as 42 days under controlled atmosphere condition and followed by 35 days of storage life at refrigeration condition.
Degree of maturity relates to bio-chemical process of living cells. Regarding fresh horticultural products, degree of maturity would be increased with the storage period. Degree of maturity of stored tomato was expressed in numeric value and presented in
As expected, higher degree of maturity was observed in stored tomatoes in both of storage conditions. Before third week of storage, degree of maturity in refrigeration condition was lower than controlled atmosphere but at the end of storage period, it was slightly higher than observed in controlled atmosphere (
In storage study, degree of color is one of the important quality parameters. Color development of fruits depends on the ethylene production and ethylene production largely depends on storage condition. Color development of tomatoes in terms of numeric value in two different storage conditions is shown in
Change in total soluble solids content in tomatoes stored in two different conditions are shown in
It was found that TSS increased in both of storage conditions. Data revealed that there was no significant (p > 0.05) difference in TSS content in tomatoes stored in both of two conditions up to 21 days of storage. At last two weeks of storage period, TSS increased significantly (p < 0.05) in tomatoes stored in refrigeration condition than stored in modified condition. This result was in agreement with the findings of Znidarcic et al. [
Change in pH value in stored tomatoes is shown in
stored tomatoes under both of conditions was not observed during the 35 days of storage study. However, pH increased at a higher rate in stored tomatoes under controlled atmosphere during the last week of storage study. This result was in line with the findings of Castro et al. [
Weight loss during storage is directly related to storage temperature and period. It is resulted because of moisture loss through transpiration. However, weight loss of fresh tomato during storage period was found almost linear under both of storage conditions (
Shelf-life of fresh tomatoes could be extended in refrigeration condition, but only lowering the temperature was not very much effective to maintain storage quality. Under refrigeration condition, continuous biosynthesis process due to high amount of oxygen level caused conversion of polysaccharides, which resulted in increasing amount of TSS and softening of tomatoes.
One of most important outcomes of this research that locally developed controlled atmosphere (CA) plant using cheap construction materials and L-ascorbic acid as an oxygen inhibitor was effective storage condition to extend the shelf-life of fresh tomatoes. Nevertheless, it could be suggested that if it was possible to maintain 1% antioxidant of tomato weight, 85% - 90% RH at storage temperature 18˚C - 20˚C or below but not less than 10˚C in CA, it would increase the shelf life 2 to 3 times more than current result. Therefore, controlled atmosphere could be introduced for increasing the shelf-life with minimum physiological changes and weight loss than normal atmosphere as well as refrigeration condition.
Md. Farid Ahmed,Md. Zahirul Islam,Md. Sazzat Hossain Sarker,S. M. Kamrul Hasan,Rakib Mizan, (2016) Development and Performance Study of Controlled Atmosphere for Fresh Tomato. World Journal of Engineering and Technology,04,168-175. doi: 10.4236/wjet.2016.42015