Refrigerated Shelf Life Evaluation and Effects of Minimal Processing on Antioxidant Capacity of

201 Pages·2017·4.98 MB·English

The University of Maine
DigitalCommons@UMaine
Electronic Theses and Dissertations Fogler Library
Summer 8-19-2016
Refrigerated Shelf Life Evaluation and Effects of
Minimal Processing on Antioxidant Capacity of
Fresh Sea Vegetables from New England
Dhriti Nayyar
University of Maine, [email protected]
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Recommended Citation
Nayyar, Dhriti, "Refrigerated Shelf Life Evaluation and Effects of Minimal Processing on Antioxidant Capacity of Fresh Sea Vegetables
from New England" (2016).Electronic Theses and Dissertations. 2491.
http://digitalcommons.library.umaine.edu/etd/2491
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REFRIGERATED SHELF LIFE EVALUATION AND EFFECTS OF MINIMAL
PROCESSING ON ANTIOXIDANT CAPACITY OF FRESH
SEA VEGETABLES FROM NEW ENGLAND

By

Dhriti Nayyar

B.Sc. North Carolina State University, 2012

A THESIS
Submitted in Partial Fulfillment of the
Requirements for the Degree of
Master of Science
(in Food Science and Human Nutrition)

The Graduate School
The University of Maine
August 2016

Advisory Committee:
Denise I. Skonberg, Associate Professor of Food Science and Human Nutrition,
Advisor
Angela Myracle, Assistant Professor of Food Science and Human Nutrition
Balunkeswar Nayak, Assistant Professor of Food Science and Human Nutrition
THESIS ACCEPTANCE STATEMENT

On behalf of the Graduate Committee for Dhriti Nayyar, I affirm that this
manuscript is the final and accepted thesis. Signatures of all committee members are on
file with the Graduate School at the University of Maine, 42 Stodder Hall, Orono, Maine.

August 19, 2016
Dr. Denise Skonberg, Associate Professor of Food Science and Human Nutrition

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© 2016 Dhriti Nayyar
All Rights Reserved

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LIBRARY RIGHTS STATEMENT

In presenting this thesis in partial fulfillment of the requirements for an advanced
degree at The University of Maine, I agree that the Library shall make it freely available
for inspection. I further agree that permission for "fair use" copying of this thesis for
scholarly purposes may be granted by the Librarian. It is understood that any copying or
publication of this thesis for financial gain shall not be allowed without my written
permission.

Signature:
Date:
REFRIGERATED SHELF LIFE EVALUATION AND EFFECTS OF MINIMAL
PROCESSING ON ANTIOXIDANT CAPACITY OF FRESH
SEA VEGETABLES FROM NEW ENGLAND

By Dhriti Nayyar

Thesis Advisor: Dr. Denise Skonberg

An Abstract of the Thesis Presented
in Partial Fulfillment of the Requirements for the
Degree of Master of Science
(in Food Science and Human Nutrition)
August 2016

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<0.05) decreased the total phenolic content and the antioxidant capacity of
the sea vegetables, however, freezing at -20 ºC for one month did not affect their TPC
and antioxidant capacity in most cases. Overall, the brown sea vegetables had higher
antioxidant capacity compared to the red sea vegetables. The results of these studies
provide important information for the growing sea vegetable industry in New England as
well as contribute to on-going sea vegetable research.
DEDICATION

I dedicate this manuscript to the four pillars of my life, maa (Rita Nayyar), papa
(Krishan Nayyar), didi (Isha Nayyar), and my fiancé, Eeshaan Asaikar.

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ACKNOWLEDGEMENTS

My sincerest gratitude to my advisor, Dr. Denise Skonberg, for her immense
investment in all her students and positively impacting me as a researcher. Thank you for
teaching me with utmost patience and contributing hugely to my personal and
professional growth. Learning under you is worth every single snow storm! I am also
thankful to my committee members, Dr. Angela Myracle and Dr. Balunkeswar Nayak for
their guidance over the past two years. I am grateful to Peter Arnold, Peter Fisher and
Seth Barker at Maine Fresh Sea Farms (MFSF) for funding a major portion of this project
and the continuous supply of sea vegetables. I am deeply inspired by your passion for
your work. I would also like to extend my thanks to the Northeast region Sustainable
Agriculture Research and Education (SARE) for granting funds to carry out a significant
portion of my thesis. Many thanks to the Graduate School for funding my tuition fees and
supporting the completion of my degree.
Katherine Davis-Dentici, thank you for bringing so much positivity and a big
broad smile every time I see you. I rightly call you my savior for helping me out in any
situation. Michael Murphy, thank you for your support with everything related to the
pilot plant, it never goes unnoticed. I am very grateful to Dr. Greg Porter for guiding me
through my statistical analyses. To all the staff and faculty in the Food Science program,
thank you for helping me in every small and big way.
No research is complete without the undying support from friends, family and
peers. A special thanks to all my seafood lab mates, Jonelo, Bouhee, Teaka, Sarah and
Jeffrey. Thank you for assisting me in my experiments, doing the dishes and making lab
work so much fun. A special mention to Bhargavi Rane, Tamanna Ramesh and Aman
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