Semester

Spring

Date of Graduation

2017

Document Type

Problem/Project Report

Degree Type

MS

College

Davis College of Agriculture, Natural Resources and Design

Department

Human Nutrion and Foods

Committee Chair

Janet Tou

Committee Co-Chair

Nicole Waterland

Committee Member

Youyooun Moon

Abstract

A comprehensive review of current literature was conducted to investigate nutrient retention, texture and color during processing and storage of green beans. Consumers do not take into consideration of the effects of processing and storage on the nutritional and sensory quality of the green beans. Freezing and canning are the main processing methods used to extend the shelf-life of green beans. Both frozen and canned green beans are blanched during processing. Green beans are either frozen after blanching or for canning undergo additional thermal processing. Ascorbic acid was found to remain stable after steam blanching at 90°C for 3.5 minutes. Freezing green beans for three months at -20°C can cause up to 41.5% of ascorbic acid to be lost while extended frozen storage of six months can cause ascorbic acid content to decrease to 49.6%. Thermally processing canned green beans at 100°C for 20 minutes caused an insignificant effect on the antioxidants ascorbic acid, phenolics and flavonoid content. Canning and freezing also affected green bean texture differently. The texture of frozen green beans remains firmer than canned green beans though both were softer than fresh green beans after 31 days of storage. The color of canned green beans is also affected by blanching and thermal processing. Frozen green beans turned light green after 31 days of storage while canned green beans became a dark green over the same storage period. Overall, for shorter shortage periods of 3-4 months, frozen green beans retain more nutrients as well as had a similar color and texture to fresh green beans. For an extended storage period greater than six months, color and texture of the canned beans do not change from when the green beans are canned. Research regarding home processing methods for green beans will help home gardeners make a more educated choice regarding the type of preservation that will best suit their individual needs. Consumers can also benefit from this research by allowing a more educated decision between commercially or home canned and frozen green beans.

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