Consumers are increasingly demanding choices of ready-made foods with excellent organoleptic and health-related properties. There are two main trends in Europe; firstly, consumers are increasingly choosing foods that are comfortable for use, secondly, the number of people who are overweight is increasing, with more consumers paying close attention to the ingredients and nutritional value of products in order to balance the amount of the food they consume per day. The aim of the research was to develop new potato main courses and to determine their nutritional value. The research was carried out at

Consumer interest in health and wellness prompted the food industry to develop alternative processing technological solutions for preserving low-acid shelf-stable foods. The aim of this study was to assess the expiration date and quality determining factors of potato main course in retort packaging. The study was conducted at the Faculty of Food Technology and the Faculty of Veterinary Medicine, Latvia University of Agriculture. Four different potato main course types -with amaranth (66% potato, 33% amaranth, 1% spices and salt), quinoa (66% potato, 33% quinoa, 1% spices and salt), bulgur (66% potato, 33% bulgur, 1% spices and salt) and chicken fillet (49.5% chicken fillet, potato 49.5%, 1% spices and salt) -were investigated. All main courses were packaged in three different packaging materials, two-layer laminated transparent polyamide/polyethylene film (PA/PE), and four-layer opaque, laminated polyethylene terephthalate / aluminium / polyamide / polypropylene (PET/ALU/PA/PP) packaging. During the 22-month storage, mesophilic aerobic and facultative anaerobic microorganisms (TPC), pH and colour L* a* b* changes in all potato main courses were tested once every month. The results demonstrated that the expiration date of potato main course in PA/PE packaging is 8 months, while the expiration date of potato main course in PET/ALU/PA/PP packaging reaches 22 months.

Thermally treated potato products in retort packaging with an extended shelf-life (up to 90 days before opening) at room temperature (20 ± 1 °C) from two Latvian vegetable processing companies (A and B) were analysed in this research. The aim of this research was to determine the presence of thermotolerant microbial contamination in thermally treated potato products in retort packaging, to ensure their safety and suitability for immediate consumption. Samples from three production batches were used. The total plate count was determined, and a microscopic examination of potato product samples was performed. Microscopic examination of microorganisms showed the presence of microbial vegetative forms in potato products from company B, but the standard investigation did not register them; therefore, Tryptone Glucose Yeast Extract Agar (TGYA), TGYA enriched with 1 % starch solution and TGYA enriched with 5 % starch solution were used for potential microorganism isolation. Samples were incubated at 25 °C; 37 °C; 41.5 °C; 50 °C; 55 °C and 60 °C temperatures under aerobic and anaerobic conditions, incubation time 12, 24 and 48 h. Facultative thermophilic Bacillus licheniformis bacteria which produce thermotolerant spores were isolated from thermally treated potato products in retort packaging from company B. The average colony count in company B samples was 1.27100 CFU/g (SD = 78.25). The presence of microorganisms was not detected in potato products produced at company A, while facultative thermophilic and thermotolerant microorganisms were found in potato products produced at company B.

Promocijas darba izstrāde līdzfinansēta no Valsts Pētījumu Programmas "Lauksaimniecības resursi ilgtspējīgai kvalitatīvas un veselīgas pārtikas ražošanai Latvijā (AgroBioRes)" (2014.-2017.), projekts Nr. 4. "Vietējo lauksaimniecības resursu ilgtspējīga izmantošana kvalitatīvu un veselīgu pārtikas produktu izstrādei (PĀRTIKA)". The research leading to these results has received funding from the National Research Program (2014-2017) "Agricultural resources for sustainable production of qualitative and healthy food in Latvia (AgroBioRes)", 4 th project "Sustainable use of local agricultural resources for the development of qualitative and healthy food products (FOOD)"