Effect of hydrophilic gums on the quality of frozen dough: electron microscopy, protein solubility, and electrophoresis studies

Hydrophilic gums have been shown to improve the shelf-life stability of frozen doughs during long periods of frozen storage. The objective of this research was to determine the effect of gums on starch and protein characteristics of frozen doughs using electron microscopy and electrophoresis studies. Frozen doughs, supplemented with three levels of gum arabic, carboxy methyl cellulose (CMC), kappa (kappa) carrageenan, and locust bean gum, were studied after day 1 and after 4, 8, 12, and 16 weeks of frozen storage. Changes in the ultra structure of the frozen doughs were investigated, as well as the solubilities and composition of dough proteins by SDS-PAGE. Scanning electron micrographs of doughs evaluated on day 0 (unfrozen) showed starch granules securely embedded in the gluten matrix. However, after 8 and 16 weeks of frozen storage, the frozen control dough without the gum additives clearly showed damage to the gluten network, and the starch granules appeared to be separated from the gluten. Doughs with locust bean gum and gum arabic showed better retention of the gluten network compared with the frozen control evaluated after different periods of storage. The SDS-soluble protein content increased while residue protein content decreased as the frozen storage time increased. After each frozen storage period, the control dough without the gum additive had the highest amount of SDS-soluble proteins and the lowest amount of residue proteins when compared with the doughs treated with gums. kappa-Carrageenan and locust bean gum had the lowest amount of SDS-soluble proteins compared with doughs with CMC and gum arabic. The frozen control had the lowest amount of residue proteins at any particular time of frozen storage. kappa-Carrageenan treated doughs had the highest amount of residue proteins, followed by doughs with locust bean gum. Doughs with gum arabic and CMC had the lowest amount of residue proteins but still higher than the control doughs.