title: Volatile generation in bell peppers during frozen storage and thawing using selected ion flow tube mass spectrometry (SIFT-MS).
abstract: To determine volatile formation during storage and thawing, whole, pureed, blanched, and raw green and red bell peppers (Capsicum annuum) were frozen quickly or slowly then stored at -18 °C for up to 7 mo, with and without SnCl(2) addition during thawing. Headspace analysis was performed by a Selected Ion Flow Tube Mass Spectrometer (SIFT-MS). After blanching, (Z)-3-hexenal had a large significant decrease in concentration since it is a heat labile compound while most other volatiles did not change in concentration. The freezing process increased volatile levels in the puree only. Slow freeze peppers had higher levels of some LOX generated volatiles during storage than quick freeze. During frozen storage of blanched samples (E)-2-hexenal, (Z and E)-hexen-1-ol, and (E)-2-pentenal increased likely because of nonenzymatic autoxidation of fatty acids while other volatiles remained constant. In Raw Whole peppers, (Z)-3-hexenal, hexanal, and 2-pentylfuran were generated during storage likely because the LOX enzyme is still active during frozen storage. However, blanched samples had higher concentrations of (E)-2-hexenal, (Z and E)-hexen-1-ol, 1-penten-3-one, and (E)-2-heptenal because of enzymatic destruction of these volatiles in the raw samples. The levels of many of the volatiles in the raw samples, including (Z)-3-hexenal, (E)-2-hexenal, (Z and E)-hexen-1-ol, hexanal, (E)-2-pentenal, and 2-pentylfuran, appeared to peak around 34 d after freezing. Pureed samples had significantly higher levels of volatiles than the whole samples, and volatiles peaked earlier. Green bell pepper volatile levels were always higher than red bell pepper. Significantly higher volatile formation occurred during thawing than it did during frozen storage.
  
  
  CONCLUSIONS
  Studying and monitoring the headspace volatiles with a SIFT-MS can give information that will help manufacturers better understand how the volatiles in bell peppers change during frozen storage. This will give valuable information to processors on how to minimize volatile changes during storage of frozen peppers.
authors.affiliation: Dept of Food Science and Technology, The Ohio State Univ, 2015 Fyffe Road, Columbus, OH 43210, USA.
authors.forename: Brendan
authors.initials: B
authors.lastname: Wampler
authors.forename: Sheryl A
authors.initials: SA
authors.lastname: Barringer
mesh_terms: D000446:Aldehyde-Lyases / Q000037:antagonists & inhibitors / Q000378:metabolism; D000447:Aldehydes / Q000032:analysis / Q000737:chemistry; D002212:Capsicum / Q000737:chemistry* / Q000201:enzymology / Q000254:growth & development; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D005511:Food Handling; D061353:Food Storage; D005628:Frozen Foods / Q000032:analysis*; D005638:Fruit / Q000737:chemistry* / Q000201:enzymology / Q000254:growth & development; D005663:Furans / Q000032:analysis / Q000737:chemistry; D000441:Hexanols / Q000032:analysis / Q000737:chemistry; D006358:Hot Temperature; D007700:Kinetics; D008084:Lipoxygenase / Q000737:chemistry / Q000378:metabolism; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D013058:Mass Spectrometry; D010422:Pentanones / Q000032:analysis / Q000737:chemistry; D010858:Pigmentation / Q000187:drug effects; D010940:Plant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D013237:Stereoisomerism; D017971:Tin Compounds / Q000494:pharmacology; D055549:Volatile Organic Compounds / Q000032:analysis* / Q000737:chemistry
chemical_list: D000447:Aldehydes; D065607:Cytochrome P-450 Enzyme Inhibitors; D005663:Furans; D000441:Hexanols; D016859:Lipoxygenase Inhibitors; D010422:Pentanones; D010940:Plant Proteins; D017971:Tin Compounds; D055549:Volatile Organic Compounds; C023599:stannous chloride; C530101:2-pentylfuran; D003577:Cytochrome P-450 Enzyme System; D008084:Lipoxygenase; D000446:Aldehyde-Lyases; C054540:hydroperoxide lyase; C057461:1-pentene-3-one