Effect of cryogenic freezing on the textural and sensoric properties of donuts

Abstract

Cryogenic freezing is a mild freezing technology due to the formation of small ice crystals. This preservation technology is well applicable for increasing the shelf life of bakery products. In our experiment, we made donut samples of matured dough, traditional dough with pork fat, and dough with increased fibre content made by adding flaxseed flour. They were fried in palm oil and also in high oleic sunflower oil. Donuts were frozen in liquid nitrogen for 60 seconds and they underwent a storage of 7 days at -18°C. Thawing at room temperature and thawing in oven were tested. We investigated how freezing, frozen storage and different thawing processes affect sample texture by penetration. The effect of freezing on water activity and sensory properties were also investigated. In our experiment we found that cryogenic freezing influenced the texture of prepared donuts, but sensory evaluation have shown that this does not lead to a decrease in popularity. In addition, a slight decrease in water activity was observed after freezing and thawing. Heating in oven proved to be the better method for the thawing process of donuts based on sensory properties of products. In addition, consumers preferred the increased fibre content of doughs.