Synergistic Effects of Nisin-Assisted Thermosonication on Quality Characteristics of Apple Juice

Abstract

Awareness in consumers towards the safety and quality of food is increasing day by day, that is why the demand for safe and nutritious food has been increased. The present study was conducted to evaluate the synergistic effects of bio preservative nisin (NS) with thermosonication (TS) on the quality and safety attributes of apple juice. The purpose of conducting the given research was to check the effects of chemically assisted TS and to provide microbial safety to the apple juice without thermal degradation. Treatments were applied by using TS (24kHz, 30^oC, 50min) in T₁ and at 60^oC in T₂, after that NS was added in treated samples at the concentration of 75 mg/L in T₃ and 100 mg/L in T_4, samples were analyzed with the interval of 5 days during storage of 15 days_.  Final results, stated that value of acidity and cloud value increased from (0.34±0.04) to (0.41±0.09) and (0.09 ± 0.02) to (1.13 ± 0.05) respectively after applying the treatment of TS and TS+NS, but decreasing trend were seen during storage interval. Treatments increased the total phenolic contents of juice from (274.53) to (291.60) in T₄ followed by T₃ but decrease to (288.45) after storage interval of 15 days. On the other hand, the significant decrease was seen during treatment and storage in the pH from (3.93) to (3.88) in T₄ and ascorbic acid from (4.09) to (3.68 mg/100mg) due to heating and increase in storage time. Nonsignificant results showed in the TSS during storage and after treatments. Treatments like TS and TS+NS improved the color of apple juice, which gave decreasing trend during storage. Total plate count decreased significantly after the treatments like T₄ (TS+NS) and T₃ from 1.97 log to 1.53 log, but microbial load increased a little bit during storage; efficiently retained by T₄ treatment. All the treatments improved in the overall acceptability of apple juice. Therefore, the findings of the given study analyzed that TS+NS treatment (T₄ & T₃) are better methods for providing quality retention and microbial safety of apple juice without thermal degradation as compared to simple TS treatment (T₁ & T₂), but both TS and TS+NS have the potential to retain quality in apple juice. Hence; the study concluded that TS+NS is an effective method to decrease microbial load without thermal degradation of quality characteristics.