Evaluation of purple onion waste from the perspective of sustainability in gastronomy: Ultrasound-treated vinegar

Abstract

Sustainable gastronomy is an important concept that improves the health and nutritional quality of society by supporting the preparation, production, and consumption of foods with environmental awareness. Purple onion (Allium cepa) is a plant with rich bioactive properties, which is well known for its use in the field of gastronomy. In this study, for sustainable gastronomy, vinegar production was carried out using the traditional method and different methods using purple onion waste collected from restaurant businesses. At the same time, ultrasound technology was used to improve the nutritional properties of the vinegar, and some properties were compared with thermally pasteurized and untreated vinegar. The bioactive components of purple onion vinegar were enriched by ultrasound using response surface methodology (RSM). The maximum optimization result for the bioactive components was achieved at 58.2 amplitude and 6.4 min. The antihypertensive and antidiabetic effects of ultrasound-treated purple onion vinegar (UT-POV) were enhanced. The most commonly detected polyphenols, such as gallic acid, catechin, protocatechuic acid and hydroxybenzoic acid, increased with ultrasound treatment. K and Zn minerals were enriched in the UT-POV sample. UT-POV has less effect on volatile compounds than thermally pasteurized purple onion vinegar (P-POV). Our results show that UT-POV significantly impairs the proliferation of HGC-27 cells. Purple onion vinegar has strong anticancer and antimicrobial effects. Purple onion vinegar treated with ultrasound was evaluated positively for sustainable gastronomy.