Date of Award

Summer 8-20-2021

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)


Food Science and Human Nutrition


Denise I. Skonberg

Second Committee Member

Jennifer J. Perry

Third Committee Member

Mary E. Camire


The European green crab (Carcinus maenas) is an invasive species which has caused considerable economic and ecological damage along U.S. coasts. Due to their small size, meat extraction from green crabs is laborious, and there is currently no well-established use for this abundant biomass. Developing a high-value, high-volume food product such as a fermented green crab sauce may stimulate the commercial harvesting of these crabs. Overall, the purpose of this research was to accelerate fermentation of green crab sauce using proteases and to gain insight into chef perspectives of fish sauce and a green crab sauce concept. The specific objectives of this research were to: (1) evaluate the physicochemical and microbial effects of proteolytic enzyme treatments (Alcalase, Flavourzyme, and Protamex) on the production of a fermented green crab sauce, and (2) survey chefs in New England regarding their perceptions of a fermented green crab sauce as a culinary ingredient. In the first study, commercial proteases were applied to chopped whole crabs and the mixture was incubated at 55°C for 48 hours, and then fermented at 37°C for 88 days. The produced crab sauce was filtered and analyzed periodically throughout the fermentation period. Percent yield and amine nitrogen content increased significantly in the enzyme-applied treatments compared to the control (without enzymes) up to day 30. Fermentation time had a significant impact on characteristics of the sauce including increases in pH, browning index, amine nitrogen, and total volatile base nitrogen, and a decrease in moisture content over time. However, there were few significant differences among enzyme treatments overall. Based on these results, commercial proteases could be applied to increase yield and hydrolysis of proteins for short term fermentations of 30 days or less. In the second study, a 14-question online survey collected perspectives of 59 professional chefs throughout New England regarding their preferences for fish sauce and feedback about a green crab sauce concept. The chefs’ preferred attributes of commercial fish sauce included medium brown color, savory aroma, transparent appearance, and umami flavor. The most important sourcing factors for chefs when purchasing ingredients for restaurants were local, sustainable, and price. Overall, chefs scored “likeliness to use” and “willing to purchase” a commercially available green crab sauce very positively. The chef survey data suggest that the ideal target customer for green crab sauce would be head chefs who focus on Asian cuisine and who are already familiar with fish sauce. The results of these studies have important implications for the production and marketing of a fermented green crab sauce. The application of commercial proteases was shown to be promising during the early stages of green crab sauce fermentation, although more research is needed to optimize protease application. Chefs were very receptive of the green crab sauce concept for the food service distribution channel, however, sensory evaluation of the crab sauce is necessary to characterize desirable flavor and odor attributes. Industrial production of a fermented green crab sauce may promote the development of a commercial fishery for green crabs and help to control their escalating populations in North America.

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Food Science Commons