Effect of vitamin E as antioxidant on the release of off-flavor form HDPE bottles

Off-flavor (including off-odor and off-taste) is a major concern with HDPE bottles used for packaging water, milk, and juices, which can greatly affect the quality of food products. The off-flavor problem is mainly due to the migration of off-flavor compounds from the bottles to the beverages. Recently, vitamin E is used as antioxidant in reducing off-flavor release from HDPE bottles. The overall objective of this work was to study the effectiveness of vitamin E and its formulation on the release of off-flavor from HDPE bottles in polymer processing.; Several factors such as antioxidant (vitamin E, BHT, and Irganox 1010), resin type (chromium-based and titanium-based), and processing machinery and/or condition (laboratory or commercial scale) affecting the release of off-flavor have been investigated. The effectiveness of antioxidants (undergo individual studies of various factors) was evaluated based on the sensory and instrumental studies. Odor and taste tests were used to determine the extent of off-flavor release from HDPE bottles in sensory study. Gas chromatography and gas chromatography-mass spectrometry were used to identify and quantify the volatile compounds released from HDPE bottles in instrumental study.; In general, vitamin E containing bottles were found to have better sensory performance (odor and taste) than those containing other antioxidants such as BHT and Irganox 1010. The identified volatile compounds were n-alkanes, 1-alkene, aldehydes, ketones, phenolics, olefins, and paraffins. Since aldehydes and ketones have low sensory thresholds, they were likely to be responsible for odor released from the bottles. In our studies, aldehydes and ketones were correlated well with sensory scores. The general consistency of the sensory and instrumental data showed that antioxidant, resin type and processing machinery and/or condition could greatly influence the release of off-flavor from HDPE bottles.; The effects of individual components in a vitamin E formulation (CF-120) on off-odor release, melt flow index, and yellowness index of HDPE resin pellets were also studied in a three-phase study. CF-120 consists of vitamin E, glycerol, polyethylene glycol-400 (PEG-400), and glyceryl monocaprylate/caprate (GMC). Phase I (preliminary experiment) study showed that GMC greatly contributed to off-odor release and melt flow index (MFI) reduction; vitamin E greatly contributed to yellow color formation. Phase II (factorial experiment) study confirmed that GMC was the major off-odor contributor. Phase III (response surface experiment) study showed that yellowness index and odor score reasonably correlated to vitamin E and GMC concentrations. In contrast, MFI and nonanal concentration did not con-elate well with vitamin E and GMC concentrations. The results are useful for designing a better vitamin E formulation for reducing off-odor, without significantly enhancing yellow color formation.