THE USE OF GLASS TRANSITION TEMPERATURE IN FORECASTING WHEY POWDER STORAGE STABILITY OBTAINED BY ELECTRO-SPARK TREATMENT

摘要

This study investigated the behavior during storage of dry whey obtained using different approaches that prevent caking (by adding silicon dioxide, electro-spark treatment of whey). Forecasting the stability of quality whey powder was carried out based on a glass transition temperature.The glass transition temperature of whey powder was measured by differential scanning calorimetry.We showed that the highest glass transition temperature (+18.5 °С) and,subsequently, the smallest difference between product temperatures and glass transition temperature were discovered in dry whey, obtained with the use of electro-spark treatment, which proved to be stable during storage.We have found that the other samples of dry whey under normative storing conditions (from 0 till 20 °С) are predominantly in rubbery state, which can influence negatively the stability of the product during storage. Based on the glass transition temperature we determined that electro-spark treatment used in the technology of whey powder allowed reaching anti-caking effect due to physico-chemical processes resulting from electro-spark charges. This was proved by calculating the stickiness and caking sensibility index and the degree of caking (to 2 %). It was experimentally proved that the dry milk whey produced with electro-spark treatment differed positively from other samples by absence of non-fermentative darkening.Whey powder produced from whey treated with electro-spark charges was characterized by the highest degree of whiteness, which did not significantly change in 8 month storage.