Title : Evaluation of edible coatings for quality maintenance of fresh cut vegetables.
Abstract:
Six different edible coatings including chitosan, pectin, alginate, starch, carrageenan and CMC were evaluated to determine their effect on physicochemical properties and microbial growth inhibition over fresh cut cucumber and carrot. Microbial load over FCV was reduced by 1.03 log cfu/g total plate count, 0.49 log cfu/g yeast and mould, 0.61 log cfu/g coliforms count whereas microbial count over fresh cut carrot got reduced by 0.94 log cfu/g total plate count, 0.54 log cfu/g yeast and mould and 0.73 log cfu/g coliforms after disinfecting fresh cut cucumber and carrot with 100 ppm sodium hypochlorite solution for 23 minutes and 8 minutes at 10°C, respectively. After disinfection pretreatment, fresh cut vegetables were coated with above mentioned edible coatings. Evaluation of coatings showed chitosan and pectin showed comparable effects in restricting the microbial growth over fresh cut cucumber. However, chitosan coated FCV exhibited minimum microbial load over FCV after 9 days of storage as compared to other coatings and control FCV samples with maintaining all other quality attributes. Therefore, chitosan was selected for further optimization studies w.r.t coating concentration and dipping time that was statistically designed and analyzed using response surface methodology. Microbial analysis for TPC, Y&M and coliform count and physicochemical analysis viz. pH, TSS, total sugars, and firmness was taken. Fresh cut cucumber dipped in 1 percent (w/v) for 5 minutes and fresh cut carrot dipped in 1 percent (w/v) for 3 minutes was found to be optimum coating conditions, respectively. The validation investigations carried out at 3 kg scale resulted in firmness 4.5 and 24 (lb), total sugars 3.7 and 6.8 (g/100g), TSS 5.2 and 8.0 (ºB), pH 5.0 and 6.5, TPC 4.0 and 3.9 (log cfu/g) ,Y&M 2.0 and 1.8 (log cfu/g) and Coliforms 2.1 and 2.0 (log cfu/g) in fresh cut cucumber and carrot with desirability of 90 percent and 93 percent, respectively. Shelf life studies of pretreated chitosan-coated fresh cut cucumber and carrot FCV cucumber and carrot were tested for a period of 12 days or till deterioration at a regular interval of 3 days under optimal coating conditions. Results revealed that chitosan coated FC cucumber and carrot can be consumed upto 12 days and 15 days, respectively while maintaining their desirable physicochemical and sensory characteristics with microbial loads under acceptable range. Microbial count over chitosan coated FC cucumber on 12th day of storage showed 4.54 log cfu/g TPC, 2.90 log cfu/g Y&M and 2.95 log cfu/g Coliforms under acceptable limits while uncoated samples had microbial count above acceptable limits on 6th day of storage. Microbial count over chitosan coated FC carrot on 15th day of storage showed 4.72 log cfu/g TPC, 2.90 log cfu/g Y&M and 2.95 log cfu/g coliforms under acceptable limits while uncoated samples had microbial count above acceptable limits on 6th day of storage. As a result, the present study found that preteated fresh cut cucumber coated with 1 percent (w/v) chitosan for 5 minutes and fresh cut carrot coated with 1 percent (w/v) chitosan for 3 minutes were able to inhibit the microbial load over FC cucumber and carrot during storage period under refrigeration conditions of 5-7º C maintaining its all physicochemical and sensorial characteristics.
