Starch identification and determination in sweetened fruit preparations

Starch is used as a thickening and gelling agent in sweetened food products such as sweetened fruit preparations (SFP). Due to a lack of efficient methods in the literature for identification and measurement of starch in such samples, this study was deemed necessary. Dialysis was used as a purification technique that allowed the preservation of starch while simultaneously eliminating saccharose. The study of experimental parameters such as dialysis membrane cutoff, treatment time, temperature, and water renewal leads to a yield of saccharose elimination of 99.4% (sigma% = 0.1%) for strawberry SFP. Enzymatic hydrolysis of starch has been done by alpha-amylase and amyloglucosidase. A research strategy relying on the use of Rechtschaffner's matrix was achieved for hydrolysis conditions study. Previous gelatinization-alkalinization treatment, starch modification, hydrolysis time, and pH have great effect on the efficacy of hydrolysis. The determination of glucose released by hydrolysis has been done with hexokinase and glucose-6-phosphate dehydrogenase. The use of this method on strawberry SFP containing 3.0% (w/w) acetylated distarch adipate leads to the determination of 92% (relative standard deviation sigma% = 3.1%) starch. This method can be considered to be efficient, specific, and reproducible for this starch in these samples.