عنوان مقاله [English]
Introduction: With enough food production in today's world, many people in the community are struggling with nutrient deficiencies and are in fact struggling with hidden hunger. The World Health Organization estimates that at least 1 in 5 people in the world suffer from iodine, zinc, iron, folic acid, calcium and vitamin A and B deficiencies (Bouis and Saltszman, 2017).Vitamins are one of the most important micronutrients that are vital to human health and are essential for survival in the body. Vitamins are organic compounds that are essential to the metabolism of nutrients, vital to the body, and to the growth and development of health (Dennehy and Tsouronis, 2010). Adding one or more micronutrients to the staple diet is said to be one of the most effective strategies to prevent micronutrient deficiency (Jafarpour and Mazandarani, 2013). Dairy dessert is a product that contains at least 50% fresh cow's milk or reconstituted milk that is prepared with authorized additives after the heat process (Miyani et al., 2016). Dairy dessert is among the children's favorite foods with its main components being milk and milk products. Vitamins are divided into two groups of water and fat soluble. Vitamins A and D are fat-soluble vitamins that are very common (Calvo and Whiiting, 2013). Vitamins A and D3 deficiency is one the most common micronutrients deficiency in most communities. Milk-based dairy products are important carriers for enrichment of foods with fat-soluble vitamins. Vitamins A or retinol are used to improve the eyesight of people in low light, such as at night and maintain eye surface health, body defense and skin health. Vitamin A does not exist purely in plant sources, but in its precursors, carotene, in various forms. It is present in 4 forms of retinol, retinal and retinoic acid (Fennema, 2008). Vitamin D, called calcifrol, is one of the essential vitamins and fat-soluble vitamins that help bone growth and health by controlling calcium and phosphorus balance. It helps in bone metabolism by enhancing the absorption of phosphorus and calcium from the intestines and by reducing the excretion of the kidneys, as well as by translating the cells of the cell's nuclei into cell growth (Holick, 2006). Probiotics are living microorganisms exerting healthful effects on the host via balancing the intestinal microflora mainly marketed as probiotic dairy products. The objective of this study was to assess the feasibility of enrichment of probiotic dairy dessert with vitamin A and D3.
Material and methods: To do so, vitamin A (2000, 4000, 6000 lu/l) and vitamin D3 (400,500, 600 lu/l) individually and combind (4000 lu/l vitamin+500 lu/l vitamin D3) were added to the dairy dessert inoculated with Bifidobacterium bifidum (108 cfu/ml). Physicochemical (pH by pH meter WTW model, acidity by the method titration in the presence of phenolphthalein with with 0.1 normal NaOH, dry matter by the method weight difference, hardness by Texture Analyzer, colorimetric (L*, a*, b*) by 14-megapixel digital camera and Photoshop CS5 application, syneresis by measuring the diameter of the created aura (100 g / cm) on the filter paper, vitamin A and vitamin D3 by HPLC), microbial (probiotic bacterial count by MRS-Agar medium ) and sensory (flavor, color, texture, and total acceptance by Hedonic 5-point) properties were evaluated over 28-d storage at 4°C. Data were analyzed by two-way and one-way variance Duncan test at 95% confidence level by using SPSS 21.
Results and discussion: The results showed that pH, hardness, vitamin D3, vitamin A and viability reduced and acidity and syneresis increased over time. The highest viability was found for T5 (2000 lu/l vitamin A+ 108 cfu/ml Bifidobacterium) showing no significant difference from other treatments (p>0.05). This may be due to the metabolic activities of Bifidobacterium bifidum by consuming nutrients such as sugars in dairy dessert and producing organic acids. The pH and acidity of dairy products is affected by the balance between the nitrogenous compounds of the products resulting from proteolytic and lactic acid reactions resulting from the fermentation activity of lactic acid bacteria. Also, with time and increased activity of probiotic Bifidobacterium bifidum, acid production increased and could increase the acidity of the samples. The reason for the decrease in texture hardness during storage can be due to increased acidity and sequestration and a decrease in dry matter of the specimens during 28 days of storage. Some studies show that by decreasing the pH during storage, irregular and non-uniform protein networks are formed and lead to high hydration in the product. Investigation of dry matter changes of probiotic dairy desserts containing different concentrations of Vitamin A and D3 showed a slight decrease during dry matter storage of the samples but these changes were not statistically significant (p>0.05). According to the results, the color of the dessert samples became brighter with increasing amount of vitamin A, and the brightness of the samples decreased with increasing amount of vitamin D3 and the color of the samples tended to darken. This was due to the clearness of vitamin A powder and darker vitamin D3 than to vitamin A and dessert samples when added to the samples. Research has shown that vitamin A loss during storage is directly affected by light and indirectly by fat content and packaging conditions. Exposure to vitamin A-containing light at wavelengths less than 500 nm causes damage to vitamins such as A, C and riboflavin, and this is called photosynthesis. The results of sensory evaluation revealed that treatment and time had significant (p < 0.01) effect on the flavor, as the amount of vitamins A and D3 increased, flavor score decreased slightly. Added vitamins A and D3 had no significant effect on variations of color scores.
Conclusion: Given the results of sensory and viability evaluation, treatment containing 500 lu/l vitamin D3+ 4000 lu/l vitamin A+108 cfu/ml Bifidobacterium bifidum was selected as the superior treatment due to the highest bacterial viability and total acceptance and the presence of both vitamins A and D3 exerting healthful effects. Suggest to investigate the circumstances and the type of packaging to preserve vitamins A and D3 during storage, the relationship between oxidation and reducing the amount of vitamins A and D3 in dairy desserts and the role of vitamin A or D3 volatile and non-volatile flavor compounds in effect on dessert dairy.