Preservation of spinach by isochoric (constant volume) freezing |
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| Authors: | Cristina Bilbao-Sainz Amanda G J Sinrod Lan Dao Gary Takeoka Tina Williams Delilah Wood David F Bridges Matthew J Powell-Palm Gideon Ukpai Bor-Sen Chiou Vivian C H Wu Boris Rubinsky Tara McHugh |
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| Affiliation: | 1. Healthy Processed Foods Research, U.S. Department of Agriculture, 800 Buchanan st., Albany, CA, 94710 USA;2. Bioproducts Research Unit, U.S. Department of Agriculture, 800 Buchanan st., Albany, CA, 94710 USA;3. Produce Safety and Microbiology Research, U.S. Department of Agriculture, 800 Buchanan st., Albany, CA, 94710 USA;4. Department of Mechanical Engineering, University of California, 6141 Etcheverry Hall, Berkeley, CA, 94720 USA |
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| Abstract: | Efforts are currently directed towards improving the quality of vegetables after freezing and thawing. One of the methods under investigation is isochoric freezing. In this study, we evaluated isochoric freezing for preserving the quality of baby-leaf spinach. We compared the properties of thawed spinach frozen to −4°C in an isochoric system with those of fresh spinach, thawed spinach frozen to −4°C in an isobaric system and thawed spinach that were commercially frozen. Spinach leaves frozen under isobaric conditions lost mass and thickness, making them softer and translucent. They also lost much of their nutrient content. In comparison, isochoric freezing maintained cell integrity and turgidity. Thawed leaves remained crunchy with characteristics similar to fresh leaves. Isochoric freezing also preserved nutritional content better than isobaric freezing, although significant nutrient losses still occurred. |
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| Keywords: | Isochoric freezing nutritional value preservation spinach |
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