Effect of freeze-drying and air-drying on the content of carotenoids and anthocyanins in stored purple carrot.

BACKGROUND: In stored freeze-dried orange carrots, carotenoids are not stable compounds. The aim of the work was to evaluate the stability of carotenoids in products obtained from polyphenol-rich purple carrots which additionally contain anthocyanins. METHODS: This study compares the effect of air-drying and freeze-drying as well as 6-month storage on the content of carotenoids, anthocyanins and total phenolics in dried products obtained from purple carrot. RESULTS: The phenolic compounds found in the greatest amounts in carrot were ferulic acid cyanidin 3-xylosylglucosylgalactoside, p-coumaric acid cyanidin 3-xylosylglucosylgalactoside, chlorogenic acid, and caffeic-quinic acid. Freeze-drying did not significantly reduce levels of carotenoids and anthocyanin content, while air-drying led to substantial losses of carotenoids, anthocyanins and polyphenols. 6-month storage of freeze-dried products caused losses of carotenoids, anthocyanins and total polyphenols of 42%, 33% and 53% respectively when compared with the raw material. In air-dried products, the losses were 66%, 33% and 36%, respectively. CONCLUSIONS: The results indicate that the combined effect of freeze-drying and 6-month storage was reduced losses of carotenoids compared to traditionally dried products.

Effect of adding essential oils of coriander (Coriandrum sativum L.) and hyssop (Hyssopus officinalis L.) on the shelf life of ground beef.

This study examined the effect of adding essential oils of hyssop and coriander at the highest concentration (0.02% v/w) sensorially acceptable to a panel of assessors on the microbiological and biochemical characteristics of stored ground beef. Vacuum-packed meat was stored at 0.5±0.5°C and 6±1°C for 15days. The greatest beneficial effect of both additives was in inhibiting the development of undesirable sensory changes (extending acceptability by up to 3days) and the growth of Enterobacteriaceae (by up to approximately 1-2 log cycles compared with the controls). The effect on lactic acid bacteria, total viable bacterial count and other groups of microorganisms investigated was minor (up to 1 log cycle) and similar for both oils. Neither did these additives significantly affect amino nitrogen levels, protease activity, the proportions of meat pigments, protein electropherograms and pH levels. This indicates the limited effect of these essential oils in the concentrations applied on preserving vacuum-packed minced beef.