Evaluation of drying techniques to preserve bioactive compounds in spruce sprouts during storage
Latvia University of Life Sciences and Technologies, Faculty of Agriculture and Food Technology, Food Institute, Lielā iela 2, Jelgava LV-3001, Latvia
*Correspondence: Klinta.Karklina@lbtu.lv
Abstract:
Spruce sprouts are a rich source of vitamins and antioxidants. Still, there is little information about the stability of compounds in different dried spruce sprouts during storage. This study aims to analyse the optimal drying method for spruce sprouts to ensure higher bioactive compound content for a shelf life of one year. Four types of spruce sprouts were analysed – fresh, dried at 40 °C, at 60 °C, and freeze-dried. Spruce sprouts were analysed for moisture, Vitamin C content, total tannin content, a-, and b- chlorophyll, total chlorophyll and total carotenoids, as well as volatile compounds in different spruce sprouts were characterised. To evaluate the optimal drying method for preserving bioactive compounds for over a year, the technique for order of preference by similarity to an ideal solution, TOPSIS, was used. According to TOPSIS, the most optimal results were observed in fresh samples. However, when analysing drying methods, the most optimal for spruce sprouts were freeze-drying and drying at 40 °C. Characterising volatile compounds in different processed spruce sprouts, regardless of the drying method, D-limonene was present at the highest concentration in all spruce sprout samples, imparting a characteristic citrus aroma. Overall, the results indicate that while fresh spruce sprouts initially contained higher levels of bioactive compounds, freeze-drying proved to be the most effective method for preserving these compounds during a year of storage. This method not only ensures long-term stability but also offers a promising approach for developing stable, nutrient-rich spruce sprout products with extended shelf life and high functional value suitable for industrial applications.
Key words:
chlorophyll, freeze drying, TOPSIS, vitamin C, Volatile compounds