Date of Award

Summer 8-19-2016

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Food Science and Human Nutrition

Advisor

Denise Skonberg

Second Committee Member

Angela Myracle

Third Committee Member

Balunkeswar Nayak

Abstract

Sea vegetables (also known as seaweeds) are gaining popularity among American consumers as a new superfood. Some sea vegetable farmers in New England have begun to distribute fresh or minimally processed sea vegetables to local restaurants and to retail distributors. However, limited knowledge about quality loss and processing effects on fresh, farm-raised sea vegetables postharvest obstructs the growth of a vibrant sea vegetable industry. The objectives of this research were to: 1) evaluate the quality changes and shelf life of four fresh sea vegetables species - dulse, Gracilaria, sugar kelp and winged kelp - during refrigerated storage, 2) determine the basic nutritional composition of these fresh sea vegetables, and 3) evaluate the effects of blanching and freezing on the antioxidant capacity of the aforementioned sea vegetables.

Fresh dulse and Gracilaria were stored at 35 oF and 45 oF for up to two weeks and periodically tested for sensory, microbial, physical and biochemical quality attributes. The species exhibited opposite trends for the effect of storage temperature: the lower storage temperature resulted in a longer acceptable quality shelf life for dulse (11 days) whereas the higher temperature resulted in a longer acceptable quality shelf life for Gracilaria (10 days), based on sensory evaluation. For the brown sea vegetables, fresh sugar kelp (February and June harvest) and winged kelp (whole fronds and slaw) were stored 35 oF and 45 oF for up to two weeks and periodically tested for sensory attributes, microbial, physical and biochemical quality parameters. The lower storage temperature maintained the quality of whole fronds and shredded slaw better than the higher storage temperature. Harvest season impacted the shelf life of sugar kelp significantly, resulting in an acceptable quality shelf life of 12 days for sugar kelp harvested in June compared to a 6-day shelf life for sugar kelp harvested in February for samples stored at 35 oF.

All four species under investigation contained ~80-90 g/100g moisture. The dry mass was rich in total minerals including potassium, calcium and magnesium but low (~2-3 g/100g) in crude lipid. The protein content was variable, with dulse containing the highest (22.1 g/100g) amount among the four species whereas winged kelp had the highest (58.4 g/100g) carbohydrate content. The highest (31.4 mg/100g) vitamin C content was found in sugar kelp whereas the lowest was found in Gracilaria (1.5 mg/100g).

The antioxidant capacity of blanched, frozen and blanched frozen dulse, Gracilaria, sugar kelp and winged kelp was compared to that of fresh samples. Blanching significantly (p

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