Influence of Heat Treatment Methods on Bioactive Compound Concentrations in Pumpkin – Guelder Rose (Viburnum opulus) Sauces

The objective of this study was to examine the suitability of heat treatment methods on concentrations of bioactive compounds in pumpkin–guelder rose sauce. Berry hybrids 2--30--K, 2--45--K and variety ‘Krasnaya Grozdj’ were selected for further research. The juice of these fruits was used to create pumpkin–guelder rose sauce samples (experimental samples) where the pumpkin puree and guelder rose fruit juice ratio was 74.5 : 13.1. To all samples heat treatment under atmospheric conditions (traditional cooking) and vacuum cooking at 0.6 bar pressure at 85 °C and 0.2 bar pressure at 75 °C temperature was performed. These samples were compared with uncooked experimental samples. Sauce chemical evaluation showed better retention of vitamin C concentrations (per dry weight) for guelder rose variety ‘Krasnaya Grozdj’ sauces cooked at 0.2 bar pressure, compared to fresh samples. Samples that were prepared with vacuum cooking methods on average showed higher total phenol concentration, antiradical activity and total anthocyanins concentration than in control samples cooked under atmospheric conditions. These observations were consistent with reports in the literature on better preservation of bioactive compounds in plant-based products that are cooked under vacuum heat treatment at lower temperatures.