FACTORS INFLUENCING QUANTITIES OF SUGARS AND ORGANIC-ACIDS IN BLACK-CURRANT CONCENTRATES

Use of endogenous non-volatile flavour components, i.e. sugars and org anic acids, in fruit juice products is desirable. A study of 133 black currant concentrates from three seasons examined variation in sugars a nd acids arising from storage of fruit at freezing or sub-ambient temp erature, seasonal differences, geographical origin and choice of conve ntional thermal-evaporative or freeze concentration technology. Compar ed with freeze concentrates, conventional concentrates had significant ly higher contents of total sugars and acids, notably malic acid, and higher fructose/glucose, lower malic/citric acid and similar sugar/aci d ratios. Concentrates from frozen fruit generally had smaller amounts of fructose, total sugars and fructose/glucose ratios than those from fresh fruit, as well as less citric, ascorbic and total acids and low er sugar/acid ratios. Principal component analysis of 40 randomly chos en concentrates showed that variance is dominated by differences in fr uctose, total sugars and ascorbic acid contents and sugar/acid ratios. Geographical origin and concentration technology were major sources o f variance but changes in post-production sub-ambient storage could no t be excluded.