According to Taoukis and Labuza (1996), vitamin losses, pigment oxidation and microbial selleck chemicals llc growth all follow a first order pattern, where the rate of quality loss is directly related to the remaining quality. In the present study the ascorbic

acid (vitamin C) stability was studied due to its importance in the human diet. In addition, since it is considered to be the most chemically unstable vitamin, one can consider that if the ascorbic acid is retained in the food, the other nutrients will also be retained. Thus its retention is considered to be an index of nutritional quality maintenance during food processing and storage (Hiatt, Taylor, & Mauer, 2010). In this work, the vitamin C content obtained at zero time was considered as 100% for the initial (A0) condition and 45% for the

final condition (Af). The final condition was defined considering that 15.0 g powder reconstituted in 200 ml water at the start of storage provided approximately 98 mg ascorbic acid. Since the recommended daily allowance for adults is 45 mg, it was considered that the product with 45% of vitamin C retention would still provide the recommended daily vitamin C allowance. Fig. 3 shows that the ascorbic acid content of the powdered guavira pulp decreased sharply between the 10th and 50th days of storage under accelerated conditions, CCI-779 solubility dmso and between the 20th and 50th days of storage under environmental conditions, and then remained practically constant up to the end of storage, presenting first order degradation kinetics up to the 50th day of storage and then zero order kinetics up to the end of storage under both storage conditions. Although significant vitamin C degradation is represented by the first order kinetics, Inositol oxygenase the overall degradation velocity of the system was calculated to check whether or not the influence of zero order kinetics. For variable order reactions (Levenspiel, 1974), the overall degradation velocity of CA may be calculated by the sum of the individual velocities (Eq. (7)).

Therefore, we applied zero order equations (Eq. (1)) and first order (Eq. (2)) separately, obtaining the velocity constants k0 and k1. equation(7) dAdt=k0+k1A In the integrated form, one obtains: equation(8) -lnk0+k1A0k0+k1A=k1t The results obtained from the first order degradation velocity for the shelf life of the product with 45% retention of vitamin C (28.99 days) did not differ significantly (p > 0.05) from those obtained from the overall degradation velocity equation (48.82 days) and experimental data (approximately 48 days). This shows that the first order kinetics prevails in the vitamin C degradation. However, the shelf life prediction from the reaction velocity equations (Eqs. (1) and (2)) reproduces only experimental values close to 50% degradation. According to Hiatt et al.