Investigation of the physicochemical properties of concentrated fruit vinegar

Abstract

Since consuming vinegar on a regular basis can contribute to the maintenance of good health, many fruit vinegar products are sold in Taiwan. Using 66 fruit vinegars purchased in local markets as samples, this study investigated the labeling, pricing and physicochemical properties of commercial concentrated fruit vinegar in order to understand their production methods and quality. Two out of the 66 samples had no label, while only 29 samples listed nutrient content. According to the labels, 26 of the fruit vinegar samples were made from juice mixed with grain vinegar (JG), while 28 samples were produced from juice via alcoholic and vinegar fermentation (F). The remaining samples were produced by fermentation and mixed with grain vinegar, alcoholic vinegar and juice. Most of the domestic products, such as mei (also called as Japanese apricot), cider, orange, lemon and blended vinegar, were produced by mixing juice with grain vinegar, whereas most imported cider and wine vinegar were produced by fermentation. Wine vinegar had the highest unit price of all fruit vinegar samples. Appearance of these vinegar samples differed significantly. The variations in pH and acidity were less than other physicochemical properties. Total sugar content of vinegar without sugar was less than 3%, while those with sugar added ranged from 8% to 64%. Most imported cider and wine vinegar samples had no sugar added, with the acidity being about 5∼7%. Most domestic products with sugar added have the average acidity of less than 3%. Variations in soluble solids content and density of the fruit vinegar were similar to the variation in total sugar content. Besides acetic acid, the major organic acids found in fruit vinegar are malic, lactic and citric acids. Mulberry vinegar was found to be higher in lactic and succinic acids than other fruit vinegar. Red wine vinegar was rich in tartaric, malic and lactic acids. The Chinese National Standards (CNS14834, N5239), which regulates edibl e vinegar focuses on "seasoning vinegar" but not "vinegar beverages". Since people are paying much more attention to health, the number of concentrated vinegar products in Taiwan is expected to increase in the future. Thus, appropriate rules are required to regulate vinegar products.