Both the rowanberries (Sorbus) and the chokeberries (Aronia) belong to the family Rosaceae. The berries of these cultivars are suitable for production of health-food products. The main components in the dry matter of fruits are carbohydrates, primarily sugars. The aim of this experiment was to determine the content of simple sugars and sorbitol in different fresh rowanberry cultivars and chokeberries and to compare the composition of these compounds after freezing and thawing of berries. The experiments were done in the Customs laboratory of the National Customs Board, State Revenue Service (Latvia). The rowanberries were picked in the Pure Horticultural Research centre, and black chokeberries were obtained from farm 'Ceplīši' (rural municipality of Pure). The contents of dry matter and soluble solids were analyzed in fresh berries, and the contents of sugars and sorbitol were analyzed both in fresh berries and in berries after freezing and thawing of 13 different cultivars of rowanberries and one black chokeberry. For determination of the soluble solids content, the refractometric method was used, and for determination of the glucose, fructose, sucrose and sorbitol content, high performance liquid chromatography was used. The results showed that rowanberries and chokeberries contained 3.24-7.24 g 100 gE-1 of sorbitol which was the dominant compound in all investigated berries. The highest content of sorbitol was found in the wild rowanberries and rowanberries Sorbus aucuparia var. sibirica, but fruits of rowanberry×pear 'Alaya Krupnaya' contained the least content of sorbitol. After freezing and thawing of berries, the content of sugars and sorbitol were decreased by 5-23% with some exclusion.

The content of carbohydrates (fructose, glucose, and sucrose) and organic acids (citric acid, succinic acid, malic acid, sorbic acid, and ascorbic acid (vitamin C)) in organically grown vegetables (carrots, parsnips, celeriacs, and red beets) and dried vegetable products were analyzed by the HPLC reverse phase and ion exchange methods. The main carbohydrate detected in fresh vegetables invariably was sucrose (1.29 – 11.17 g 100 gE-1). Fructose and glucose were found in similar ranges (0.09 – 2.47 g 100 gE-1, 0.14 – 3.02 g 100 gE-1 respectively). A similar distribution of carbohydrates was determined in dried products. The highest fructose and glucose contents were found in fresh carrots - 2.47 g 100 gE-1 and 3.02 g 100 gE-1 respectively; but in dried carrot products – 14.53 g 100 gE-1 and 15.43 g 100 gE-1. High amounts of sucrose were found in red beets: 11.17 g 100 gE-1 in fresh samples, and 48.50 g 100 gE-1 in dried products. Malic and citric acids were detected as the main acids of fresh vegetables. Highest citric acid amount was in red beets (266.19 mg 100 gE-1), whereas celeriacs and parsnips had a high malic acid content. The results from this study demonstrated variability and concentration range of carbohydrates and organic acids, wherewith the organoleptic profile of the products. Dried products are considered as a good source of energy.

The major sugars in six cultivars grown in Latvia are analysed. The content of glucose, fructose and sucrose in strawberry, blackcurrant and redcurrant berries was determined by applying the method of high performance liquid chromatography (HPLC). By using the obtained calibration curves, concentrations of diverse sugars were found in the analyzed samples. Fructose or fruit-sugar, the same as glucose, is mainly the source of energy in the human body though it is decomposed faster and easier than glucose. In all the researched berry cultivars, the amount of fructose was the largest, particularly in blackcurrants. Six strawberry, black- and redcurrant cultivars were evaluated as raw materials for industrial production. The investigation involved chemical and sensory analyses of fresh berries. The results indicate that pH and sugars of fresh berries influence their quality. Furthermore, high level of sugar adversely affects taste stability. Taste degradation in berries is parallel to flavour deterioration. It is concluded that the main emphasis should be given to the properties of fresh berries.

Growing interest of consumers in healthy eating has provided the development of new range of food. Therefore the task of research was to determine the nutritional value, calculate energy value and investigate the sensory properties of yoghurt samples enriched with flakes from biologically activated hull-less barley grains and malt extract. Results showed that by adding flakes from biologically activated hull-less barley grain and malt extract it was possible to improve the nutritional value of yoghurt, i.e., increased protein, carbohydrate and decreased fat content. The energy value of yoghurt samples enriched with flakes from biologically activated hull-less barley grain and malt extract ranged between 65.96 and 75.72 kcal 100 gE-1, which is significantly lower comparing with mean energy value of commercial yoghurts. The changes of sensory properties were affected by the amount of added malt extract in yoghurt samples. The optimal amount of added malt extract for sensory evaluation in yoghurt samples was determined as 2%. The content of carbohydrate in yoghurt sample enriched with 5% of biologically activated hull-less barley grain and 2% of malt extract was two times lower than commercial yoghurts therefore its energy value was significantly lower. Yoghurt enriched with flakes from biologically activated hull-less barley grain and malt extract could be competitive.

Chemical composition of crops before winter is important for successful overwintering of plants. The aim of the research, carried out from 2007/2008 till 2009/2010 at the Research and Study farm ‘Vecauce’, was to investigate the influence of agricultural practices (sowing date, sowing rate, and fungicide application) and meteorological conditions during winter on the content of sugar in apical bud and root of two types of winter oilseed rape (Brassica napus L.) cultivars. The content of sugars (monosaccharides) in apical bud and root in autumn and following spring was analysed using the Luff–Schoorl method. Sugar content in apical bud and root of winter oilseed rape in autumn and spring differed depending on the trial year, because of different, even contrary (in season 2009/2010), meteorological conditions. Sugar content was higher in plant parts developed when rape was sowed on earlier sowing dates, but it was substantially influenced by the sowing date only on some occasions. Sowing rate had no impact on sugar content in apical bud and root. Application of a fungicide as a growth regulator had no significant impact on the result, but sugar content decrease during winter 2009/2010 in the root of winter oilseed rape was smaller when fungicide as growth regulator was applied.

Highbush blueberries are thought to provide protection against oxidative damage of free radicals and contribute to positive health benefits. They have been studied little in Latvia; therefore, the aim of study was to evaluate the soluble solids content, titratable acidity and sugar content of berries harvested in 2010. Seven varieties of cultivated highbush blueberries (Vaccinium corymbosum L.) grown in Latvia were analysed. Analyses were done for frozen berries of varieties ‘Bluecrop’, ‘Chandler’, ‘Chippewa’, ‘Duke’, ‘Northblue’, ‘Patriot’ and ‘Polaris’. All experiments were performed at the Latvia University of Agriculture, Faculty of Food Technology. The content of titratable acids (TA) was detected using standard method ISO 750:1998 by titration with 0.1N NaOH. Soluble solids content (SSC) was analysed using standard method ISO 2173:2003 by hand refractometer. Sugars (fructose, glucose and sucrose) were analysed by high-pressure liquid chromatography HPLC analysis. Results showed that there are significant differences between varieties (p is less than 0.05) for all parameters. TA content varied from 0.4 – 1.2%, SSC - 8.5 – 10.8 degBrix and total sugars from 7.6 to 9.3 g 100 gE-1. The highest ratio between sugars and titratable acids was for ‘Polaris’ while the lowest – ‘Chandler’ and ‘Bluecrop’.

The research was done in 2006 with the aim to observe the earliness and sugar content of melons (Cucumis melo L.) in Tukums region of Latvia. Five lines of Latgale's melons ('8', '14', 'S4(3)', '5(2)', and '4(3)') and five varieties ('Noirdes Carmes', 'Ogen', 'Vedrantais', 'Cantaloup de Bellegarde', and 'Jaune Canaris') from South Europe were grown in high plastic tunnels: five plants from each line and variety. The most appropriate melon line for growing in Latvia conditions was selected according to earliness and sugar content. The study showed that Latgale's melons (Latvian origin) are most suitable for growing in high plastic tunnels under Latvia's conditions. Also some of South Europe melon varieties proved to be suitable for growing in Latvia conditions. All Latgale's melon lines were earlier than South Europe varieties. The highest sugar content was observed in Latgale's melon line '8' (113 g kg¡1) and in South Europe varieties 'Jaune Canaris' (110 g kgE-1) and 'Cantaloup de Bellegarde' (96 g kgE-1). The research demonstrated that in Latvia successful cultivation of melons is possible by using high plastic tunnels.

The experiment was carried out in 1990, 1991, 1993 in the Rumokai Research station of the Lithuanian Institute of Agriculture. The following nitrogen norms were analysed: 0(0+0), 45(0+45), 45(45+0), 90(45+45), 90(90+0), 135(90+45), 135(135+0), 180(135+45), 180(180+0), 225(180+45). Sugar production is negatively affected by soluble non-sugar substances (soluble potassium and sodium salts, amines) that prevent crystallization of sugar. Norms of nitrogen fertilisers increased the amount of: potassium by 8.9-38.2%, sodium - 11.0-54.4%, alpha-amine N - 43.0-163.5 %, while additional application of nitrogen -45 kg ha*[-1) - resulted in the increase of: 1.0 - 7.9% potasium, 1.0-8.0 % sodium, 18.2 - 44.9 % alpha-amine N. Strong positive corelation (eta=0.99) has been established between the norms of nitrogen fertilisers and soluble non-sugar substances. Potassium, sodium and alpha-amine N negatively influence the sugar content roots (eta=-0.59). Among the 14 analysed varieties, the amount of low soluble non-sugar substances was significant in the roots of Kristall, Accord and Extra varieties. The highest yield of white sugar has been found in the varieties of Freja, Anna, Accord, Extra (7.3-7.7 t ha*[-1)).