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Food Science and Technology

Print version ISSN 0101-2061On-line version ISSN 1678-457X


TORRES, Alexia; GUERRA, Marisa  and  ROSQUETE, Yrelur. PREDICTING A DIETETIC FORMULA SHELF LIFE USING THE AVAILABLE LYSINE DECREASE. Ciênc. Tecnol. Aliment. [online]. 2001, vol.21, n.2, pp.129-133. ISSN 0101-2061.

This study estimated the shelf life of a dietary formula for children with diarrhea, using the decrease of available lysine as an indicator of deterioration. Product samples were packaged in multilaminal pouches (paper-plastic-foil) and stored at 25, 30 and 35°C, for two months. The available lysine was measured weekly and the reaction of deterioration kinetics and its relationship with temperature was calculated. At the end of the study, the remainder of available lysine was of 38.5 (at 25°C), 15.3 (at 30°C) and 14.1% (at 35°C).The findings of the study indicated a first order reaction kinetics, dependent on the storage temperature based on the Arrhenius approach, with an activation energy of 15.17 kcal/mol, falling within the lipid oxidation range. According to the product characteristics [lipids content (17.5%), protein (17.3%) and water activity of 0.46], the decrease of available lysine could be explained by the interaction between lipid oxidation products and proteins. Based on a critical value of 0.422 g lysine/100g product, the product shelf life was predicted at temperatures different from those of experimental conditions. At temperatures below 30°C, the shelf life would be extended up to 9 months at 15°C, 6 months at 20°C and 3 months at 28°C, as a function of the chosen indicator.

Keywords : available lysine; kinetics deterioration; shelf life; dietetic product.

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