Yeast performance characterisation in different cider fermentation matrices

ArticleNitrogen content management before fermentation is often used in cider production to avoid sluggish fermentations. In addition to enhanced fermentation rates, the proper nitrogen content in the apple must may have an impact on the flavour characteristics of cider. This research aimed to assess yeast performance in two different commercially available musts with similar non-limiting yeast available nitrogen (YAN) content. In addition to fermentation kinetics, volatile ester production by yeast, and sensory properties of the final product were evaluated. The results showed that the fermentation rate and consumption of sugar and nitrogen sources by yeast did not vary between the two different musts. Yeasts consumed more malic acid in the environment of higher initial malic acid content. The content of volatile esters and sensory properties of the final products varied significantly. The occurrence of intense sulfur off-flavour was noted in one of the products

The Stability of Phenolic Compounds in Fruit, Berry, and Vegetable Purees Based on Accelerated Shelf-Life Testing Methodology

Evaluating the stability of polyphenols in fruit, berry, and vegetable purees helps to assess the quality of these products during storage. This study aimed to (1) monitor the stability of total phenolic content (TPC) in four-grain puree with banana and blueberry (FGBB), mango-carrot-sea buckthorn puree (MCB), and fruit and yogurt puree with biscuit (FYB); (2) study the effect of aluminum-layered vs. aluminum-free packaging on the changes in TPC; and (3) assess the suitability of accelerated shelf-life testing (ASLT) methodology to evaluate the stability of polyphenols. The samples were stored at 23 °C for 182, 274, 365, and 427 days. The corresponding time points during ASLT at 40 °C were 28, 42, 56, and 66 days, calculated using Q10 = 3. The TPC was determined with Folin–Ciocalteu method. The results revealed that the biggest decrease in TPC took place with high-pH FGBB, which contained fewer ingredients with bioactive compounds. Minor changes were seen in FYB and MCB, which had lower pH values, and contained a larger amount of ingredients that include polyphenols. In addition, the choice of packaging material did not affect the TPC decrease in each puree. Finally, it was concluded that the ASLT methodology is suitable for studying the TPC changes in such purees, but the corresponding Q10 factors may vary and should be determined based on the chemical profile and ingredient list of the product