Strawberry, sugar contents

Oszmianski J, Wojdylo A and Kolniak J. 2009. Effect of 1-ascorbic acid, sugar, pectin and freeze-thaw treatment on polyphenol content of frozen strawberries. LWT-Food Sci Technol.42(2) 581-586. 

Other fruit spirits are distilled from fresh or frozen fruits or their juices (blueberries, raspberries, strawberries, currants, apricots, peaches and others) while adding alcohol. Pomaceous fruit spirits are made from fresh fermented apples or other pomaceous fruits, from the whole fmit or its juices without the addition of sugar-containing substances, sugar or alcohol of another kind with a minimum alcohol content of approx. 38% by vol. 

Fruit nectars are produced from fruit slurries or whole fmits by homogenization in the presence of sugar, water and, when necessary, citric and ascorbic acids. The fruit content (as fresh weight) is 25-50% and is regulated in most countries, as is the minimum total acid content. Apricots, pears, strawberries, peaches and sour cherries are suitable for nectar production. The fruits are washed, rinsed, disintegrated and heated to inactivate the enzymes present. The fruit mash is then treated with a suitable mixture of pectinolytic and cellulolytic enzymes. The treatment degrades protopectin and, thus, separates the tissue into its individual intact cells ( maceration ). 

An isomer of citric acid is (1J ,2S)-1-hydroxypropan-1,2,3-tricarboxylic acid (8-67), also known as D-isocitric acid u-threo isomer), which is another intermediate of the citric acid cycle. This acid is the dominant acid in blackberries (Table 8.17) and occurs in other fruits in small or insignificant amounts (e.g. in apples). The isocitric acid content is one of the most important markers in the estimation of the proportion of fruit in coloured fruit mixtures, for example in mixtures of blackcurrants, strawberries and raspberries with apples. The concentration ratio of citric acid to isocitric acid is also employed for the detection of adulteration, and can reveal the addition of synthetic citric acid to optimise the taste of fruit drinks, especially in the case of added sugar. 

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