The dietary fibre is edible parts of plants' carbohydrates that are resistant to digestion in human small intestine. Diets naturally rich in dietary fibre support to prevent constipation, improve gastrointestinal health, glucose tolerance and the insulin response, and reduce the risk of colon cancer, hyperlipidemia, hypertension and other coronary heart disease risk factors. About 45% of the dietary fibre intake comes from grains and grain mixtures. In Latvia, there are neither data, nor investigations of the dietary fibre content in grain products during processing and in the end products in which manufacturers and consumers are interested. The aim of this paper was an approval of dietary fibre determination methodology by using analytical equipment the Full option science system (FOS) Analytical Fibertec E 1023. The dietary fibre determination experiments were carried out in the Research Laboratory of the Department of Food Technology at the Latvia University of Agriculture in 2009. The Total Dietary Fibre (TDF) content was analyzed in the samples of rye whole grain flour, rye whole grain bread, and wheat biscuit. Experiments showed that the fibre content in rye whole grain flour is 13.8 g 100 gE-1, in rye whole grain bread - 11.6 g 100 gE-1, and in the wheat biscuit - 1.9 g 100 gE-1. Reached data are comparable with results of other researchers' data.

Carrots (Daucus carota L.) are a globally important vegetable crop providing a source of important nutritional compounds through their carotenoid content whilst adding flavour and texture to many diets across the world. The current research focuses on the evaluation of sugars, vitamin C and dietary fibre content in ‘Nante’ hybrid carrots. The research was accomplished on fresh in Latvia cultivated carrots harvested in Zemgale region in the first part of October 2011 and immediately used for experiments. Late-bearing hybrids of ‘Nante’ carrots were used for analysis: Nante/ Berlikum, Nante/Maestro, Nante/Forto, Nante/Bolero, and Nante/Champion. The major sugars (fructose, glucose and sucrose) were determined by applying the method of high performance liquid chromatography, vitamin C - by titration with 0.05 M iodine solution, and dietary fibre - using standard method No 985.29. In the present experiments it was found that there are significant differences in the sugar, vitamin C and dietary fibre content between different carrot hybrids. The highest content of total sugars was found in Nante/Maestro and Nante/Champion 7.99 g 100 gE-1 and 7.57 g 100 gE-1 hybrids in fresh weight, respectively. The lowest total sugars content was in Nante/Berlikum hybrid − 4.03 g 100 gE-1. Vitamin C content in carrot hybrid Nante/Maestro was the highest 17.61±0.17 mg 100 gE-1, but in hybrid Nante/Champion - the lowest 8.39±0.17 mg 100 gE-1 of fresh weight. The dietary fibre content in analysed carrot samples ranged from 34.25±0.47 g 100 gE-1 in Nante/Maestro to 25.78±1.54 g 100 gE-1 in Nante/Champion hybrids.

The aim of this study was to investigate amino acid content, biological value and dietary fibre content of conventional and organic pea (Pisum sativum L.) and buckwheat (Fagopyrum esculentum M.) flours. Results showed that pea flours contained high amounts of aspartic acid, threonine, serine, glycine, alanine, valine, isoleucine, leucine, tyrosine, phenylalanine, histidine, lysine and arginine while glutamic acid, proline, methionine and tryptophan were found in similar or smaller amounts comparing with wheat flour. The differences of various amino acids between conventional and organic pea flours were insignificant. The content of aspartic acid, threonine, serine, glycine, alanine, valine, histidine, lysine and arginine was high in buckwheat flours in comparison with wheat flour. There were significant (p is less than 0.05) differences in the individual amino acid contents across buckwheat flours. Significant (p is less than 0.05) variation existed in the content of essential amino acids among samples, whereas the results concerning the proportion of essential amino acids in total amino acids showed insignificant (p is greater than 0.05) differences between pea flours and buckwheat flours (34.80 – 35.77% and 29.96 – 33.90% respectively). The highest content of lysine was found in pea flours, and it formed about 23% of essential amino acids content. For pea flours the total dietary fibre amount varied between 15.28 g 100 gE-1 for conventional and 27.24 g 100 gE-1 for organic pea flour. Pea and buckwheat flours could be characterised as a good source of dietary fibre with significantly (p is less than 0.05) higher content of total dietary fibre comparing to wheat flour.

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.