The objective of the research was the shelf life extension of a salad with meat in mayonnaise. The microbial stability of the salad with meat in mayonnaise packaged under vacuum, in modified atmosphere, and using 'Sous vide' technology was examined and compared with conventionally packaged (in ambient air) salad. The salads were packaged in polyamide/polyethylene pouches with barrier properties as well as in pouches made from biodegradable plasticized poly-β-hydroxybutyrate or polylactic acid film. Control samples without preservatives were packed in traditional polypropylene containers covered with non-hermetic lids. PURASA L Powder Opti Form (sodium lactate) in the amount 5 g kgE-1, 10 g kgE-1, and 15 g kgE-1, and ethyl alcohol in the amount of 2 ml were used as single preservatives for separate samples. The studies of the samples were carried out after 1, 3, 7, 10, 15, 18, 25, 29, 42, and 52 storage days at the temperature of +4+-0.5 deg C. Experimentally the quality of the salad with meat in mayonnaise was characterized by measuring the total plate count of microorganisms. The obtained results indicate that different packaging technologies and addition of preservatives show significantly different influence on the microbial growth in different samples. 'Sous vide' packaging technology was effective for the shelf life extending and guarantee of safety of the salads with meat in mayonnaise.

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.

Three spectrophotometric methods were compared for the assessment of milk fat oxidation: the AOCS (American Oil Chemists' Society) 2-thiobarbituric acid (TBA) value direct method, the TBA method of Aristova, and the modified method for the estimation of total carbonyl compounds in oils of Endo et al. Two cow milk fat samples – a fresh fat, obtained from fresh milk, and a rancid fat, obtained from a rancid commercial butter by means of high-speed centrifugation (15.871 × g, 30 minutes at 40 deg C) – were analyzed several times in a 22-day period after sample preparation. A positive linear correlation between absorbance and storage time was established in all used methods. The method of Aristova is appropriate for exact determination of oxidation products. This method had rather good R2 value (0.85) of the fresh fat sample results; however, the coefficient of variation (45.78%) showed rather large deviations between parallel analyses. The methods of AOCS and Endo et al. can be used for the assessment of the dynamics of fat oxidation by reporting absorbance values from the assay directly. By these methods rather high R2 values (0.86, 0.93) of the fresh fat sample results were obtained; the coefficients of variation also were satisfactory (10.13%, 11.12%). The last two methods are cheaper and require smaller sample amounts (less than 0.2 g), while the method of AOCS is the most time-consuming method.

Apples are the most popular and common fruits in Latvia. Storage technology is crucial to preserve fruit quality as long as possible. Choosing the appropriate gas content of the storage environment can prolong storage life two to three times for apples. The aim of the research was to compare six different type of apple grown in Latvia, which was stored in diverse conditions. All experiments were performed at Latvia State Institute of Fruit-Growing through 2011 – 2012. For fruits before storage, 1-methylcyclopropene (1-MCP), which blocks the emission of ethylene, was used. Apples were stored in a cooler and in ULO type plastic bags in a modified environment with two different gas contents. The temperature of the environment was +2 ±1 °C with 90% relative humidity. Changes in physicochemical (soluble solids, total acids and flesh density) indexes were examined before and during the storage. The results showed 1-MCP has a positive effect on quality preservation of fruit. Fruits stored in ULO type plastic bags (gas content: 1.5% O2 and 2.5% CO2) had the best results in preservation of physico-chemical indexes. Examination of results revealed that physico-chemical indexes changed the most in samples stored in the cooler.

Kvass is a non-alcoholic beverage produced by fermenting kvass mash with yeast; alcohol content in kvass must be less than 1.2% alcohol by volume. Microbiological safety of kvass is an important issue because European Regulation No 2073/2005 on microbiological criteria for foodstuffs does not provide microbiological criteria for kvass production. Microbiological safety of kvass depends on raw materials, personal hygiene, environment, kvass blending and filtration. Experiments were carried out at the Latvia University of Agriculture Department of Food Technology from November 2013 to January 2014. The aim of this work was to assess the microbiological environment changes during kvass production process and shelf-life. Understanding the development of dynamic of microbiological environment provides a better management for kvass production processes. Samples of bread kvass were analysed during production (12 and 13 h) and storage (36, 60, 84, 132, 136 h) at 3 ± 1 °C to determine kvass quality. Yeasts (LVS EN ISO 21527 - 2: 2008), lactic acid bacteria (ISO 9332:2003) and total plate count (LVS EN ISO 4833:2003) were determined in kvass samples. Microorganisms in kvass were identified using API identification system; the dominating microflora in kvass was Saccharomyces cerevisiae and Leuconostoc mesentericus. Changes of total plate count during fermentation and maturation were not significant (p is greater than 0.05).

Venison is well known as a traditional meat type in Europe, and it is lower in calories, cholesterol and fat content than common cuts of beef, pork or lamb. The aim of the current research was to determine physico-chemical parameters such protein, fat, pH, moisture content as well microbiological quality of pickled venison during storage. Beef as a control was analyzed for comparison of obtained results. The meat (2×3×2 cm) pieces were pickled in vinegar marinade (composition: tomato sauce, mayonnaise, vinegar, lemon, onion, parsley, paprika, basil, black pepper, rosemary, salt) at 4±2 °C temperature for 48±1 h. The marinated meat was placed in polypropylene trays and hermetically sealed with high barrier polymer film under modified atmosphere (C02 40%+N2 60%) without and with iron-based oxygen scavenger sachets (Mitsubishi Gas Chemical Europe Ageless®). As a control, packaging in air ambiance packed pickled products was used. During storage time, the moisture and protein values significantly (p is less than 0.05) decreased and pH, fat content and colony forming units significantly (p is less than 0.05) increased in the pickled venison samples of all packages. Slower changes in pH of pickled venison and in the protein and moisture content of marinated beef were observed in modified atmosphere with oxygen scavenger during storage.

A study was done at the Latvia State Institute of Fruit-Growing, evaluating new domestic plum (Primus domestica L.) selections, for which in 2008 -2010 some fruit quality characteristics were studied. In result of evaluation four new cultivars were selected from the breeding material and in 2010 handed in for cultivar registration in Latvia. Cultivar 'Ance' is early ripening one month before 'Victoria'. Cultivar 'Adele' is medium ripening one week before 'Victoria'. Fruits keep well in cool storage. Cultivar 'Sonora' is medium ripening one week after 'Victoria' and self-fertile. Fruits of this cultivar keep well in cool storage, too. Cultivar 'Lotte' is medium-late ripening two weeks later than 'Victoria', and is partially self-fertile. Average of three years, the highest soluble solids content was found for cultivar 'Adele' (13.28 Brix%), but cultivar 'Sonora' had the total content of acids (1.28 g 100 gE-1). Significant changes in flesh firmness were observed at different storage times for cultivars 'Ance' and 'Lotte'. Significant variations in the total content of acids were determined for 'Ance'. Whereas cultivar 'Sonora' demonstrated substantial fluctuations in soluble solids content. Correlations between firmness and soluble solids content were observed for cultivars 'Ance' (r=-0.731), 'Adele' (i=-0.436) and 'Sonora' (r=0.526). Cultivar 'Lotte' produced correlations between firmness and total content of acids (i=-0.536). Significance of interaction was determined within cultivars, years, and years x cultivars.

Sherbet with crunchy peanut chips could be classified as milk pomade. It is one of popular sweets in Latvia produced by Joint-stock Company Laima, which is one of the oldest producers of sweets in the Baltic States. Freshly made sherbet is soft and savoury but after several days’ storage at the open air gradually hardens, the product loses eye appeal, taste and becomes unmarketable. This problem limits the shelf life, so sherbet with crunchy peanut chips can be marketed only at the local market. The target of this study was to clarify the situation on the market in Latvia and to examine an issue of Latvian consumers’ awareness of milk pomade sweets – sherbet quality indicators, packaging and its presentation to consumers, as well as the sherbet market expandability. A questionnaire was developed – 800 respondents answered on the 14 questions – how well-recognized the milk pomade sweet – sherbet is, what the main features for this kind of sweets selection by consumers are, which quality indices are important for consumers. One of most important questions was to get know the consumers opinion about sweets, mainly sherbet possible packaging kind and the market turnover. Summarizing the questionnaire data, the response from consumers in Latvia was heartening – they like milk pomade candies. As a primary quality defect the hardness of sherbet was mentioned. Eliminating this main failing of quality, the demand of sherbet on the market could rise, as well the product marketing opportunities will grow.

The traditional consumption of citrus juices as a breakfast beverage has historical ties to obtaining one’s daily requirement of vitamin C. Vitamin C is one of the most important vitamins found in citrus juices, including orange juice. The aim of the study was to determine the effect of processing and storage on the content of vitamin C in orange juice varieties of ‘Valencia’ and ‘Navel’ of orange juice. The content of vitamin C (mg 100 gE-1) was determined with the iodine method in freshly squeezed orange juices and in pasteurized and packaged in aseptic bags orange juices of ‘Valencia ‘and ‘Navel’ variety, after processing and during 24 weeks of storage at 20 ± 1 °C and 5 ± 1 °C. The study results showed that the average content of vitamin C in freshly squeezed orange juice ‘Valencia’ was found at 33.56 mg 100gE-1 but in freshly squeezed orange juice ‘Navel’ the content of vitamin C was higher than in ‘Valencia’ variety orange juice average at 46.18 mg 100gE-1. The loss of vitamin C for both orange juices on average about 7% during processing The storage study showed that after 24 weeks of storage at 5 ± 1 °C and at 20 ± 1 °C, in pasteurized orange juice ‘Valencia’ the content of vitamin C decreased by 9.83% and 19.73 respectively. In the pasteurized orange juice ‘Navel’ the content of vitamin C decreased by 8.53% and 15.24% respectively.

The American cranberry (Vaccinium macrocarpon Ait.) is a perspective and marketable crop both in Latvia and foreign markets, but berries are affected by rot in storage. The aim of the study was to detect the incidence level of cranberry fruit rot at the beginning of storage period in different places in Latvia. In 2007 - 2011, two hundred sound berries (out of 1000) were randomly collected by hand along a diagonal from five different cranberry plantations from locations all over Latvia. Berries were kept in plastic bags for a month and refrigerated at +7 °C. At the end of November, berries were sorted and rotten berries were separated from the sound ones. Over the period of 2007 - 2011, the incidence of storage rot reached 12 - 15% at the end of November, with an upwards trend observed every year, but the hot and rainy summer of 2010 significantly reduced the quality of fruit in storage, peaking on the average 33% of decayed berries. The incidence of fruit rot varied among the inspected cranberry plantations, but a tendency was observed that older plantations produced more rotting fruit and incidence of the disease was 12 - 50% after a month’s storage in the oldest plantation. The application of fungicides during the vegetation season did not affect development of post-harvest rot. Storage rot was a problem in the cranberry samples from all inspected plantations in Latvia, and in future the incidence of fruit rot is expected to increase.