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Studying the microbiota of food materials is important from sanitary, spoilage and technological perspectives. Due to manual harvesting, grading and packaging of date fruit (Phoenix dactylifera L.), it's not surprising to find bacteria of human origin in date fruit products. On the other hand, microbes present in date palm, especially high moisture content fruits, could produce lactic acid and acetic acid and make the fruit sour, so this kind of microbes potentially could be useful especially in food fermentation and vinegar production. In this project, seven varieties of date fruits were examined chemically and microbiologically. Total solid and acidity of dates were between 72% to 86% and 0.06% to 0.78% respectively. Isolated bacteria were identified by 16S rDNA amplification and restriction analysis (ARDRA), sequencing and 16S rRNA gene comparison. The results show Staphylococcus epidermidis, Aerococcus, Bacillus and Leuconostoc mesenteroides are the present bacteria in local date fruits.

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Discovering new strains with useful industrial and pharmaceutical capabilities and avoiding the import of microbial strains from three economic perspectives, passive defense and conservation of the country's microbial genetic resources are of great importance. The presence and activity of appropriate microbes is an essential factor in the success of fermentation processes. Fermented foods and beverages are among the most important and best natural sources for discovering useful strains. In this study, samples of traditional date vinegar were obtained from Kerman market and their physicochemical (pH, acidity, total soluble solid, total phenolic compounds, and antioxidant activity) and rheological properties (consistency coefficient and flow behavior index) were investigated, also their microbial population were assessed by molecular methods (ARDRA and 16S rRNA gene sequencing) for the presence of acetic acid bacteria. The result of this study was to identify two species of acetic acid bacteria, namely Acetobacter pasteurianus and Komagataeibacter europaeus. In addition, Lactobacillus sp., Paenibacillus sp. and Staphylococcus epidermidis were detected in vinegar samples. On the other hand, vinegar sample were different in terms of microbial load and the type of available microbes. Date cultivar, production method and vinegar age are the possible causes of this variations. Finally, the application of acetic acid bacteria identified in this study as starter culture for fruit vinegar production is suggested. These bacteria were stored with FCC-10971 and FCC-10973 codes in the Food Culture Collection of Shahid Bahonar University of Kerman and can be ordered by other researchers.

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Marmalade is a processed product of some plant organs such as fruit, flower, fruit peel and tuber in which the plant parts used are small and well homogenized. Sugar is used as a sweetener in the preparation of marmalade. In this study, the use of date syrup as a substitute for sucrose used in marmalade formulation was studied. The constrained mixture design was used to achieve the optimal formulation and the effect of sugar substitution with date palm syrup on properties of marmalade was studied. The ingredients used in the formulation were plum paste (35-65%), sugar syrup (0-65%) and date syrup (0-65%). Ten formulas were produced based on the constrained mixture design and their physical, chemical and sensorial properties were investigated. The results showed that plum paste had the greatest effect on increasing the viscosity and total acidity of marmalade, while total soluble solids decreased with increasing the amount of plum paste in the formulation. The L^* index of the samples decreased with increasing date syrup and plum paste and the redness of marmalade increased with increasing plum paste. Sensory evaluation of the produced formulations showed that the increase in plum paste increased the consistency, spreadability, color and overall acceptance, while the sweetness and taste and flavor were more affected by the increase in date syrup. Optimal formulation was obtained in the ratios of 58% plum paste, 12% sugar syrup and 30% date syrup and in the optimal formulation the total acidity, total phenolic compounds, and viscosity of marmalade at 20 °C were equal to 2.07 g citric acid/100 g, 112.4 mg gallic acid/100 g, and 3961 cp, respectively.

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