Effect of Pasteurization and Chemical Preservatives on the Quality and Shelf Stability of Apple Juice
Effect of pasteurization and chemical preservatives on preservation of apple juice at ambient temperature for 3 months was investigated. The treatments studied were control (T0), pasteurization alone (T1), Un-pasteurized + 0.1% potassium sorbate (T2), pasteurized + 0.1% potassium sorbate (T3), un-pasteurized + 0.1% sodium benzoate (T4), pasteurized + 0.1% sodium benzoate (T5), un-pasteurized + 0.05% potassium sorbate 0.05% sodium benzoate(T6), pasteurized + 0.05% potassium sorbate 0.05% sodium benzoate(T7), un-pasteurized + 0.1% potassium sorbate 0.1% sodium benzoate (T8), pasteurized + 0.1% potassium sorbate 0.1% sodium benzoate (T9). Ascorbic acid decreased significantly in T0, T1, T3 and T5 while in the effect of rest of the treatment it was non-significant. With storage the ascorbic acid content decreased from 3.31 to 1.00 mg 100 g-1. Treatments and storage period have a significant effect on percent acidity. Lowest value for acidity was observed in T8 and T9 (0.41%) and highest in control (0.52%). It increased from 0.34 to 0.52% with 0 to 90 days storage, respectively. Maximum values for pH were noted in T9 (3.64) and minimum in T0 (3.07). However, with storage time, pH values decreased consistently with the advancement of storage time. Reducing sugars increased from 7.12 to 7.65% with the passage of storage time while the reverse was true for the non-reducing sugars. T0 and T1 have maximum non reducing and minimum reducing sugars. Effect of treatments on non-reducing was more profound as compared to reducing sugars. As might be expected, sensory quality (color and flavor), decreased with increase in storage time, however, the remained within the acceptable. Treatments T6, T7, T8 and T9 were more effective in maintaining the sensory quality compared to other one. Minimum microbial load was observed in T9 and maximum in T0 and T1 (uncountable). Among all the treatments T9 was most effective in retaining nutritional, hygienic and sensory quality of apple juice.