Kinetics of Protein Quality Loss in Enriched Pasta Stored in a Sine Wave Temperature Condition

Authors

  • J. Y. CHEN,

    1. Authors Chen, Bohnsack, and Labuza are with the Dept. of Food Science & Nutrition, Univ. of Minnesota, 1334 Eckles Ave., St Paul, MN 55108.
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  • K. BOHNSACK,

    1. Authors Chen, Bohnsack, and Labuza are with the Dept. of Food Science & Nutrition, Univ. of Minnesota, 1334 Eckles Ave., St Paul, MN 55108.
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  • T. P. LABUZA

    1. Authors Chen, Bohnsack, and Labuza are with the Dept. of Food Science & Nutrition, Univ. of Minnesota, 1334 Eckles Ave., St Paul, MN 55108.
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  • This paper is scientific journal series No. 13017 from the Univ. of Minnesota Agric. Exp. Station. This project was supported in part by the Univ. of Minnesota Agricultural Experiment Station Grant No. 18-78 and 18-72, and Grant No. PFR-7910370 from the National Science Foundation. This research was supported by federal funds and is not subject to copying restrictions.

ABSTRACT

The rate of loss of protein quality in enriched pasta was studied at constant temperature (30, 37 and 45°C) and under a continuous sine wave temperature fluctuation (25/45°C with a 24-hr period). Both loss of lysine by the fluoro-dinitro benzene (FDNB) method and a bioassay (Tetrahymena thermophila growth) for protein quality were employed. Significant loss of protein quality occurs in about 1 yr at temperatures above 30°C. The bioassay method showed that nutrient losses other than lysine could be occurring. Data from the constant temperature studies were used to predict the losses that occurred for the sine wave condition using the Hicks-Schwimmer model as modified with an Arrhenius approach. The prediction model gave about 15% error in comparison to actual losses. In addition, the rate of loss for the sine wave (25/45°C) was greater as predicted than the rate of loss at a constant mean temperature of 35°C.

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