The research focuses on the study of physically-chemical and microbiological parameter changes in Latvian wild cranberries during convective drying. The research was accomplished on fresh Latvian wild cranberries. The following quality parameters were controlled during the experiments: moisture content (oven-dry method), content of vitamin C (LVS EN 14130:2003), content of polyphenol (HPLC), preparation of samples for microbiological testing (LVS EN ISO 7218:2007), enumeration of yeasts and moulds (ISO 21527-2:2008(E)), counting of lactic acid bacteria (LVS ISO 13721:1995), and total plate count (LVS EN ISO 4833:2003A). The research detected the following optimal convective drying parameters of wild cranberries: temperature – +50±1 deg C and drying time – 20.3 hours. The moisture content of dried berries equalled to 9.0±0.1%. The content of vitamin C decreased 1.9 times in wild cranberries dried at the temperature of +50±1 deg C compared with the content of vitamin C in non-dried cranberries and was 13.05 mg 100 gE-1 in dry matter. The results of current experiments show, that the content of such polyphenols as gallic, caffeic, and epicatechin acids decreased 9.70, 9.90, and 11.68 times, respectively, during the treatment at temperatures up to +50±1 deg C compared with the initial content of these compounds in non-dried berries. The drying temperature substantially influences the microflora development in cranberries. It is possible to decrease significantly the content of LAB, mould, and fungi in berries provided the drying temperature of the wild cranberries does not exceed +50±1 deg C, thus prolonging the ready product shelf-life.

Fruits and vegetables are a major source of antioxidants. The aim of current research was to study and compare the antiradical activity, the total polyphenol content (TPC) and the total flavonoid content (TFC) in dried carrots (Daucus carota), pumpkins (Cucurbita maxima), leeks (Allium ampeloprasum var. porrum) and black radish (Raphamussativus) using a traditional convective drier and a microwave-vacuum drier. For each vegetable steaming as pre-treatment was used. Vegetables were harvested in Latvia in 2012, gathered when ripe and then dried. Analyses were made in Latvia University of Agriculture, Faculty of Food Technology laboratories. The total polyphenol content was determined by the Folin- Ciocalteu method and the total flavonoid content - using spectrophotometric method. The antiradical activity was analyzed by the 2,2-diphenyl-1-picrilhydrazyl (DPPH) assay. The results of experiments demonstrate that the total amount of polyphenols ranged from 98.97 to 623.70 mg gallic acid equivalent (GAE) 100 gE-1 in dry weight and the total amount of flavonoids ranged from 40.32 to 100.23 mg catechin equivalent (CE) 100 gE-1 in dry weight. The value of DPPH antiradical activity for vegetable samples ranged from 6.10 to 45.14 percents.

Potato (Solanum tuberosum L.) is one of the most important agricultural crops for human consumption and high amount is produced worldwide every year. Potato peel waste is a zero value by-product, which occurs in big amounts after industrial potato processing and can range from 15 to 40% of initial product mass, depending on the peeling method. Food waste utilization causes great concern in food industry in Europe and many scientific works were written on this topic in the last years offering solutions and original approaches. Present article aims to summarize the review of available literature on industrial potato peel waste application possibilities in food production industry. Scientific articles on food waste management, potato peel chemical composition and recycling methods have been studied. The main results show, that there is a big potential for potato peel extract as an antioxidant in food systems due to its high phenol content. In addition, potato peel powder could serve as a partial flour replacement in dough up to 10 g 100 gE-1 of flour weight without causing significant changes in sensory properties. Potato peel waste can serve as a solid substrate for fermentation. Further investigations in the present field are needed in order to evaluate full potato peel waste application potential.