Quality Attributes of Ultrasound-Treated Prebiotic Fibre-Enriched Strawberry Juice

Abstract

Strawberries are amongst the most desirable fruits with a rich flavour, appealing taste, high fibre content and many other health benefits. Diets rich in dietary fibre provide many health benefits. In the present work, strawberry juice was prepared in two batches, one with preservative sodium benzoate (treated) and another without (untreated). Prebiotic fibre i.e., apple pomace was added to both batches in concentrations of 5%, 8%, and 11%. Dietary fibre in both batches was analysed by enzymatic-gravimetric method. The additional analyses included pH, acidity, total soluble solids (TSS), colour, total phenolic content (TPC), antioxidant, ascorbic acid, anthocyanin, microbial and sensory parameters. Dietary fibre was increased significantly in all the treatments as well as TS, while pH and acidity were not affected. Ascorbic acid, anthocyanin, antioxidant, total phenolic content, and sensory analysis of treatment 2 (T2, 8% treated) showed the best results. The microbial load on the other hand increased more in the untreated batch. The T2 treatment of both the batches was given ultrasound treatment. The sonication temperature (20 oC), frequency (20 kHz), and power (650 W) were kept the same, and the time was varied (0, 15, 30, 45, and 60 minutes). Dietary fibre showed a slight increase as fibre became more soluble by cavitation in sonication while pH acidity and TSS were not significantly affected. Anthocyanin increased, but only at lower sonication times. Antioxidants, total phenols, and colour and sensory parameters were significantly improved with sonication time. Similarly, the microbial load was reduced significantly.

Keywords

• strawberry juice
• prebiotic fibre
• apple pomace
• ultrasound
• nutrition
• stability