Effect of ultrasound assisted extraction of dietary fiber from pineapple peel and its application with anthocyanin rich black rice

Abstract

The present study was focused primarily on the optimized extraction of dietary fiber (DF) from pineapple peel (PP) waste using alkaline and combined alkaline ultrasound methods and it was used with antioxidant rich black rice to prepare cookies with tailored physicochemical properties. The extraction of alkaline ultrasound extracted DF (AUEDF) was optimized using response surface methodology (RSM) conducted with central composite design (CCD). The optimum processing conditions for the AUEDF extraction method was solvent: solute (26.15 ml/g), ultrasound amplitude (34.32%) and sonication time (29.91 min), which gave the highest yield of DF (71.88%). Further, AUEDF yielded higher total DF content with well aligned and uniform fibrous structure, better thermal stability, crystallinity, water holding capacity, and oil holding capacity as compared to alkaline extracted dietary fiber (AEDF). The cookies were prepared by substituting wheat flour with extracted DF and black rice powder in flour formulation. The characteristics properties of the cookies in terms of texture, color, and sensory attributes were evaluated. The hardness and lightness of cookies were found to decrease with an increased concentration of black rice powder. Fuzzy logic was used for sensory evaluation, in which the cookie containing 30% black rice powder was found as the best sample. The quality attributes of cookies such as taste, and texture can be modified by the adopted strategy, which, are considered as important attributes for consumer acceptance followed by appearance and flavor. The results of the present investigation evinced that DF of pineapple waste utilization can be an excellent source for preparation of cookies with black rice. Novelty impact statement Dietary fibre (DF) from “Kew” variety pineapple peel was extracted via alkaline‐ultrasound and alkaline extraction methods and comparison revealed that the DF extracted from the former evinced uniform fibrous structure, better thermal stability, crystallinity, and other functional properties over the latter extraction method. Cookies were developed using DF and antioxidant‐rich black rice in the wheat formulation and the texture (hardness) and color of cookies decreased with increased black rice powder contents. Fuzzy logic was used to evaluate the preferred sensory properties of cookies and fortified cookie containing 30% black rice and 6% DF was selected as the best sample.