Drying Studies of Spinach Using Tray and Sun Drying Methods and Its Quality Evaluation During Storage

Abstract

The fresh sp1nach (Chenopoiacea, genus Beta ) 1s more commonly used after cooking because of its perishable nature During peak period, most of the crop IS wasted due to lack of proper post harvest process1ng techniques The fresh green sp1nach (soft stems and leaves) 1f properly dned, packaged and stored may help in increasing its availability dunng lean periods. The present studies were conducted to develop dehydrated spmach so as to enhance the availability of spmach dunng off season The fresh spinach were pretreated by three methods (i) Dipping in solution contain1ng 0.1% magnesium chloride. 0.1% sod1um b1carbonate and 2% potass1um metab1sulphite in distilled water for 15 mm. at room temperature (ii) Blanch1ng 1n boiling water for 2 mm (ui) Blanching 1n boiling \1.1ler containing 0.5% sodium metabisulphite for 2 min The ratio of spinach to pretreatment mixture was mamta1ned at 1 :5 (w/w). After pretreatments, the spinach were loaded in perforated stainless steel trays at the rate of 2 0, 2.5 and 3.0 kg/m2 tray area and dried at 40, 50, 60 and 70°C temperature in tray dryer w1th constant a1r velocity of 2.0 m/s. The open sun drying was also carried out during the day time (temp 37-45°C. RH 25-37%) The untreated samples of spinach were dried as control samples. Expenments were also conducted to study the effect of drying conditions on quality i.e. chlorophyll content. v1tamin C and rehydration characteristics The three best samples selected on the bas1s of sensory analySIS were stud1ed for storage quality for 180 day. The study revealed that total dryin~ lim.: considerably reduced With the mccease 1n drying air temperature from 40 °C to 70 ·. C mc.ud1ng open sun drying. The maJor dry1ng look place in falling rate period except some accelerating period in open sun drying initially The chlorophyll content and ascorbic cvnlent decreased with increase in temperature and increased with loading density. The rehydration ratio 1ncreased with decrease in temperature from 70 to 50 °C but d .. creased from 50 to 40 °C From sensory evaluation and storage studies. 11 can be con.:luded that the prOduct quality in terms of chlorophyll. ascorbic ac1d and rehydration characteristics were found to be most acceptable when fresh spinach samples were "retreated with solution of 0.1 Of. MgCI2+0.1% NaHC03 +2% KMS and dried at 50 °C \,,th 2.5 kg/m2 1oadmg dens1ty