Horticultural produce are stored at lower temperature because of their highly perishable nature. There are many methods to cool the environment. Hence, preserving these types of foods in their fresh form demands that the chemical, bio-chemical and physiological changes are restricted to a minimum by close control of space temperature and humidity. The high cost involved in developing cold storage or controlled atmosphere storage is a pressing problem in several developing countries. Evaporative cooling is a well-known system to be an efficient and economical means for reducing the temperature and increasing the relative humidity in an enclosure and this effect has been extensively tried for increasing the shelf life of horticultural produce in some tropical and subtropical countries. In this review paper, basic concept and principle, methods of evaporative cooling and their application for the preservation of fruits and vegetables and economy are also reported. Thus, the evaporative cooler has prospect for use for short term preservation of vegetables and fruits soon after harvest. Zero energy cooling system could be used effectively for short-duration storage of fruits and vegetables even in hilly region. It not only reduces the storage temperature but also increases the relative humidity of the storage which is essential for maintaining the freshness of the commodities.

Investigations were carried out to see the impact of blanching time, pretreatment and storage and packaging on the physico-chemical properties of solar dehydrated cauliflower. The processing treatments selected for the study were blanching time of 3, 5, 7 and 9 min, potassium metabisulphite (KMS) pretreatment having 0.5%, 1.0% and 1.5% concentration level and storage in high-density polyethylene, laminated aluminium foil and polypropylene. The cauliflowers were further processed and dehydrated in solar dryer before packing it into different packaging materials. Packed dehydrated cauliflower was stored for 6 months at room temperature. The stored cauliflower samples were tested periodically for their moisture content, rehydration ratio, rehydration coefficient, ascorbic acid and browning. Ranking of blanching time, chemical concentration level and packaging materials were statistically analysed by using SAS package. The samples with 9 min blanching time, followed by dipping in 1.0% KMS solution, and packed in laminated aluminium foil showed better results in comparison with other treatments.

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Fresh cauliflower was cut into florets, blanched, treated and spread in trays to dry by means of a solar drying process. The influences of packaging materials, blanching time, and potassium metabisulphite (KMS) concentration levels on the quality of solar dehydrated cauliflower up to 6 months of storage were studied. Ascorbic acid (vitamin C) present in fresh cauliflower was 74.61 mg (100 g) )1 . Results revealed that ascorbic acid concentration decreased with an increase in blanching time but its retention was high in cauliflower dehydrated by solar drying. Dehydrated cauliflower had 581.37 mg (100 g) )1 of ascorbic acid in samples treated with 0.5, 1.0 and 1.5% of KMS with 3 min blanching at day zero. Washing cauliflower florets in tap water reduced the microbial load as compared with the unwashed sample. Processed and dehydrated cauliflower, packed in three types of packaging materials did not show presence of fungi even after storage for 6 months. In almost all samples, permissible levels of bacterial counts were observed after 6 months of storage. All the samples were also found to be free from Escherichia coli. It was found that blanched samples (blanching done for 7 min) treated with 0.5% KMS, dehydrated and then packed in laminated aluminium foil (LF) were the best in regard with nutritional and microbiological quality of dehydrated cauliflower.

Garlic peeling is a tedious, key, costly and time consuming unit operation in garlic processing. A power operated garlic peeler having a cylinder-concave mechanism was developed with an intention to reduce cost and time. Physical properties of garlic relevant for peeler development were identified and measured. The average length, width, thickness, geometric mean diameter, sphericity, weight of garlic segment and weight of 1,000 garlic segment were measured as 26.3 mm, 10.4 mm, 8.7 mm, 13.3 mm, 0.5, 1.8 g and 1,813 g, respectively. An experimental garlic peeler having cylinder covered with 10 mm thick rubber was fabricated and evaluated for its performance with crop-machine parameters viz., cylinder speed (29, 36 and 42 rpm), cylinder-concave clearance (8, 10 and 12 mm), moisture content (23.1, 27.7, 33.4 and 40.5 % wet basis) and concave mechanisms. Crop-machine parameters were optimized based peeling efficiency and they found to be cylinder speed of 36 rpm, cylinder-concave clearance of 10 mm, mild steel square (8 × 8 screen). Prototype garlic peeler was evaluated with the optimized crop-machine parameters. The peeling efficiency, yield of peeled garlic and unpeeled garlic, damage and peel separation were 86.6, 86.2, 4.7, 9.15 and 96 %, respectively with a machine throughput capacity of 27 kg/h and the energy requirement of 1.15 kw-h. Operation cost of the peeler was determined on the basis of fixed and variable cost and found to be INR 22.9/h. The developed garlic peeler saved INR 16.11/kg (94.99 %) and 1.63 (97 %) man hours in comparison to the hand peeling of garlic.

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