[Development and optimization of an isotonic sports drink]

Within a research program on food products for athletes starting from natural apple concentrate, the design, manufacture and control of isotonic beverages, was undertaken. The dilution conditions for the apple concentrate were established studying several salts combinations which will supply those electrolytes that are eliminated through sweat and have to be replenished. They are sodium, potassium, chloride, magnesium and calcium in concentrations such as to supply an osmotic pressure similar to that observed in blood. The addition of a premix of vitamins (B1, B2, B6, B12, C, E, folic acid, niacin, pantothenic acid and biotin) in several levels of the Recommended Daily Allowance (RDA) (100, 75, 62.5, 60 and 30% of the RDA) was assayed. The obtained formula tasted salty and medicine-like, therefore the vitamin content had to be reduced, supplying 30% of the RDA in a premix constituted by those vitamins which are the most important for physical activity (B1, B2, B6 and C). The quality of the formula was optimized considering variables such as flavor, color and maltodextrin levels by using methods of sensory evaluation. In the elaborated beverage controls such as pH, acidity, total solids (degree Bx), relative density and soluble solids/acidity ratio complying with the corresponding standards, were carried out. In addition, chemical composition, caloric value, microbiological and sensory quality, were controlled. The fruit juice was packed in a 250 ml self-supporting"Doy-Pack"-like bag. Both, microbiological and sensory quality were good, and the caloric value was 101.18 Kcal/250ml. Shelf life studies at two different temperature conditions 15-25 degrees C and 3-5 degrees C, were carried out. The limiting factor was flavor which defined a shelf life of at least 3 months, stored at refrigeration temperature (3-5 degrees C). The formulated beverage supply the electrolyte concentrations which allows to be characterized as isotonic beverage, recommended for athletes.