Effect of different drying methods on quality attributes of beetroot (Beta vulgaris) slices

摘要

Purpose - The purpose of this paper is to evaluate the effect of different drying methods on quality attributes of beetroot slices. Design/methodology/approach - Three drying methods (sun, oven and freeze-drying) were applied to dry fresh slices of beetroot cultivar (Beta vulgaris). The chemical composition, minerals, nitrate, betalains, total phenolic, total flavonoid and color were measured for fresh and dried slices. Findings - The chemical composition, minerals, nitrate, bioactive compounds and color were measured for fresh and dried slices. Regardless of the drying method, the results showed that the chemical composition, total energy, minerals and nitrate of the dried slices were significantly ( p=0.05) increased compared to that of fresh slices. Sun and oven drying of the slices significantly ( p=0.05) reduced total betalain and betacynin. However, betaxanthin was significantly ( p=0.05) increased. Total phenolics content of fresh beetroot was significantly ( p=0.05) increased after sun and oven drying but total flavonoids were decreased. The 2,2,-diphenyl-2-picryl-hydrazyl (DPPH) of fresh beetroot was increased significantly ( p=0.05) after sun and oven drying. The measurement of the color of the powder showed that there is a decrease in lightness (L) depending on the drying method applied. A maximum reduction in lightness was observed in powder of sun-dried slices. The color of the powder obtained from freeze-dried slices was stable compared to other drying methods. Practical implications - Beetroot is a rich source of nutrients but with short shelf life. Dried beetroot has more keeping quality than the fresh one. Originality/value - The study uses beetroot as a rich source of nutrients as well as natural antioxidant source. Betalain compounds are preserved in beetroot and a high source of phenolics and flavonoids. Flavonoids are a group of phenolic products of plant metabolism with high antioxidant properties to protect against diseases without side effect