Controlled release of α-tocopherol, quercetin, and their cyclodextrin inclusion complexes from linear low-density polyethylene (LLDPE) films into a coconut oil model food system.

Polymer additive migration into a food product is dependent upon numerous factors including the original concentration of the additive in the polymer, its solubility in the food, its diffusion coefficient in the polymer, its partition coefficient between the polymer and food, temperature, and time. The limited solubility of quercetin in linear low-density polyethylene (LLDPE) did not allow release from the film due to phase segregation of the quercetin in the bulk polymer. Increasing the molecular weight of α-tocopherol by ß-cyclodextrin inclusion complexation can greatly reduce its diffusion coefficient in LLDPE. Ziegler-Natta and metallocene LLDPE contain different crystalline structure morphologies and diffusion path networking arrangements that allow for differences in additive release rates. Effective controlled-release packaging should combine ß-cyclodextrin complexation of additives and polymer morphology control to target delivery of an optimal antioxidant concentration to achieve prolonged activity, resulting in extended shelf life foods.

Effect of antioxidant (alpha-tocopherol and ascorbic acid) fortification on light-induced flavor of milk.

The effectiveness of added antioxidants against oxidation off-flavor development in light-exposed milk was evaluated using sensory and chemical analysis. Sensory testing for similarity showed no perceivable difference between control milk and milk with added (1) 0.05% alpha-tocopherol (TOC) and (2) 0.025% alpha-tocopherol and 0.025% ascorbic acid (TOC/ASC), but did demonstrate a perceivable difference when adding (3) 0.05% ascorbic acid (ASC) alone. Subsequently, sensory testing for difference showed a significant difference in oxidation off-flavor between light-exposed control milk and light-exposed milk with added TOC/ASC, whereas milk fortified with TOC was not different from control. Gas chromatography-olfactometry showed that more aroma-active flavor compounds were observed in light-exposed milk treated with TOC and TOC/ASC than light-exposed milk with no added antioxidants. The thiobarbituric acid reactive substances (TBARS) test verified chemically the extent of oxidation in control and antioxidant-treated milk samples. Milk that was exposed to light for 10 h showed a significantly higher TBARS value (0.92 +/- 0.09 mg/kg) than milk that was protected from light (0.59 +/- 0.184 mg/kg), or milk that was treated with TOC/ASC (0.26 +/- 0.092 mg/kg). Direct addition of low levels of antioxidants (TOC/ASC) to milk protected its flavor over 10 h of light exposed storage.