According to recent reports, the global market for melatonin is worth 700 million USD in 2018 and would reach 2,790 million USD by 2025, growing at a CAGR of 18.9% during 2019 to 2025. Having regard to the prevalence of sleep and circadian rhythm disorders and a clear tendency to increase the demand for melatonin, and the current lack of alternative green and cost-efficient technologies of its synthesis, the supply of this remedy will not be enough to guarantee melatonin supply and affordability on a global scale. The emergence of naturally occurring melatonin and its isomers in fermented foods has opened an exciting new research area; there are still, however, some obscure points in the efficient microbiological biosynthesis of melatonin. This review summarizes the research progress and recent evidence related to melatonin and its isomers in various foodstuffs. Additionally, one possible way to synthesize melatonin is also discussed. The evidence pointed out that the presence of melatonin and its isomers is not exclusive for grapes and grape-derived products, because it can be also found in sweet and sour cherries. However, different species of both Saccharomyces and non-Saccharomyces yeasts could be used to obtain melatonin and melatonin isomers in the process of alcoholic fermentation biotechnologically. The availability of L-tryptophan has been a key factor in determining the concentration of indolic compounds produced, and the utilization of probiotic lactic acid bacteria could help in the formation of melatonin isomers during malolactic fermentation. These approaches are environmentally friendly alternatives with a safer profile than conventional ones and could represent the future for sustainable industrial-scale melatonin production. K E Y W O R D S alcoholic fermentation, cherry, melatonin, Saccharomyces, yeast 1 ORIGIN AND PHYSIOLOGICAL FUNCTIONS OF MELATONIN Melatonin (MEL), or N-acetyl-5-methoxytryptamine, is a hormone, an indolamine that predominantly appears in plants, microorganisms, and mammals. Primarily, MEL was studied as a neurohormone of the pineal gland, which was discovered for the first time by Lerner, Case, Takahashi, Lee, and Mori (1958). The precursor of this molecule is solely the amino acid L-tryptophan

Development of fruit growing and fruit science in Latvia has always been closely linked to the development of the whole country. After the founding of the independent Latvia state in 1918, fruit growing developed rapidly. Although in the Soviet times the situation was not favourable for quality fruit growing, research and breeding continued with good results. After Latvia regained independence, private land property rights were restored, and interest in intensive orchard establishment and growing technologies increased rapidly, which demanded change in the research focus. At present, the Latvia State Institute of Fruit-Growing is the leading institution in this field, working in cooperation with Pūre Horticultural Research Centre, Latvian Plant Protection Research Centre, Institute of Agrobiotechology, and Faculty of Food Technology, Latvia University of Agriculture, Laboratory of Plant Mineral Nutrition, Institute of Biology, University of Latvia. Research is carried out in the following directions: breeding and cultivar evaluation; genetics and molecular biology; plant pathology and entomology; orchard management; experimental processing and storage.

No abstract

No abstract

Apple cultivars are an integral part of the Latvian State Program for Preservation and Sustainable Use of Genetic Resources for Food and Agriculture. Latvian apple (n = 109) cultivars of local origin, nominated as National Plant Genetic Resources, were analyzed with eight simple sequence repeat (SSR) markers recommended by the European Cooperative Programme for Plant Genetic Resources (ECPGR) Malus/Pyrus working group and a marker for scab resistance gene (Vf). All SSR loci exhibited a high level of polymorphism – 12 to 39 alleles, 18.75 in average, with high observed heterozygosity (Ho) ranging from 0.64 to 0.89 and a mean of 0.78. The gene diversity (polymorphism information content value) varied from 0.79 to 0.90, with an average of 0.86. All cultivars could be distinguished with the tested set of SSR loci, with a high frequency of rare (38%) or unique (26%) alleles. For the Vf gene, all three possible genotypes (VfVf, Vfvf and vfvf) were detected for 1, 6 and 102 varieties, respectively. The analyzed germplasm showed high genetic diversity, particularly landraces, while the modern cultivars clustered mainly into two groups. Cluster analysis did not reveal a clear pattern with well-defined groups, but confirmed some relationships based on known or putative pedigrees, as well as suggesting the possible parentage of some cultivars.