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Effect of fruit types and temperature on formation of volatiles in the lipoxygenase (LOX) pathway

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2015, Master of Science, Ohio State University, Food Science and Technology.
Volatiles in the headspace of tomato, bell pepper, tomatillo, strawberry, apple and pear with and without enzyme activity were measured during and after fruit tissue disruption in real time using selected ion flow tube mass spectrometry (SIFT-MS) at 4, 25, 37 and 45 °C for 60 min. Lipoxygenase (LOX) activity was measured using the adsorption of conjugated dienes formed from linoleic acid. In tomatoes, bell peppers and tomatillos, (Z)-3-hexenal, (E)-2-hexenal and hexanal increased rapidly after blending, peaked and declined, while in strawberry, apple and pear they sometimes peaked and sometimes remained constant over the 60 min. In tomato and bell pepper, the peak levels of 6C aldehydes ((Z)-3-hexenal, (E)-2-hexenal and hexanal) in the LOX pathway had good correlations to LOX activity, which was greatest at 25 °C. In contrast, tomatillo, strawberry, apple and pear had lower LOX activities. Their 6C aldehydes did not show strong correlation with LOX activity and the volatiles increased with increasing temperature had highest concentrations at 45 °C. The concentrations of 6C alcohols (hexen-1-ol and 1-hexanol) in the LOX pathway did not correlate to LOX activity for any of the fruits. Among volatiles that are not the major 6C aldehydes and alcohols, the pathway of (E)-2-octenal, (E)-2-heptenal, 2-pentenal and 1-penten-3-one did not consume many precursors. In strawberry, apple and pear, most 13-hydroperoxide of linoleic acid or hexanal converted to hexanoic acid. Compared to other fruits, strawberry and apple had higher concentrations of hexenyl acetate and hexyl acetate. In tomato, bell pepper and tomatillo, although fruit with higher ratio of linoleic acid:linolenic acid also had higher ratio of hexanal:hexenal, there was no significant correlation between these two ratios. In strawberry, apple and pear, there were good correlations between linolenic acid content and concentrations of (E)-2-hexenal, hexenal and hexen-1-ol. Volatile levels of almost all 6C aldehydes and 6C alcohols in the LOX pathway were significantly higher with enzyme activity than without at all temperatures. Continual blending resulted in volatile levels continually increasing in the headspace over 30 min, but the volatile levels decreased significantly once blending stopped, after long time blending. The proper blending time for this study was determined to be 30 sec.
Sheryl Barringer (Advisor)
Luis Rodriguez-Saona (Committee Member)
John Litchfield (Committee Member)
86 p.

Recommended Citations

Citations

  • Han, Y. (2015). Effect of fruit types and temperature on formation of volatiles in the lipoxygenase (LOX) pathway [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1430955718

    APA Style (7th edition)

  • Han, Yafei. Effect of fruit types and temperature on formation of volatiles in the lipoxygenase (LOX) pathway. 2015. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1430955718.

    MLA Style (8th edition)

  • Han, Yafei. "Effect of fruit types and temperature on formation of volatiles in the lipoxygenase (LOX) pathway." Master's thesis, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1430955718

    Chicago Manual of Style (17th edition)