Journal Articles

Permanent URI for this collectionhttps://mro.massey.ac.nz/handle/10179/7915

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Author: search.filters.author.Singh JSubject: search.filters.subject.Antioxidant activity

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    Phlorotannins from New Zealand brown seaweeds: Extraction, antioxidant activity, and food applications
    (Elsevier Ltd, 2025-12-01) Zhang R; Khan A; Singh J; Kaur L
    Brown seaweed, a type of marine macroalgae, is a sustainable resource for human consumption that plays an important role in several cultures, including Aotearoa New Zealand. Brown seaweeds have a relatively high content of phenolic compounds and, exclusively, phlorotannins, which have garnered increasing attention due to their bioactive properties. Applications of these phenolic compounds have been developed for therapy, food additives, material manufacturing, and fertilisers. Among these, their antioxidant property is especially important for the food industry, but limited research has been conducted. This review investigated the nutrition profile of New Zealand brown seaweed species, which are rich in macronutrients, and addressed safety concerns regarding heavy metals and iodine. Phlorotannin content, extraction methods, and their promising antioxidant activities were then compared between New Zealand and global brown seaweeds. According to the current research, they have comparable phlorotannin content and antioxidant activities. More importantly, the potential of applying brown seaweed species as an antioxidant in food matrices was explored. Although successful trials have utilised (New Zealand) brown seaweed extracts as antioxidants for various foods, their widespread commercial use remains rare. The seaweed industry in New Zealand has not been established, and the seaweed is heavily reliant on wild harvest and imports. In conclusion, more effort is needed to develop a comprehensive, evidence-based understanding of New Zealand's brown seaweeds, ultimately enabling the commercialization of this promising resource as antioxidants in food products.
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    The role of herbal teas in reducing the starch digestibility of cooked rice (Oryza sativa L.): An in vitro co-digestion study
    (Elsevier GmbH on behalf of Society of Nutrition and Food Science e.V, 2023-11-01) Aumasa T; Ogawa Y; Singh J; Panpipat W; Donlao N
    Herbal teas are well known for their antidiabetic effects due to the abundance of phenolic acids, flavonoids, and tannins. An in vitro co-digestion test was conducted to observe influence of herbal teas (HTs) i.e., beal fruit (BA), mulberry leaf (MB), gymnema leaf (GM), and chrysanthemum flower (CS) on starch digestibility of cooked rice and to elucidate correlation analysis of phytochemicals and their antioxidant activities during in vitro starch hydrolysis (SH). HTs prepared from GM and MB showed highest reduction of SH, kinetic constant and estimated glycemic index (eGI) of cooked rice, followed by BA and CS. Besides, MB and GM teas decreased the eGI of cooked rice up to 15%, followed by BA and CS teas, respectively. Phytochemicals and their antioxidant activities were positively correlated to SH, with both parameters displaying a higher decrease in intestinal phase when compared to gastric phase during in vitro co-digestion. These results indicate a strong interaction among phytochemicals and α-amylase in influencing glycaemic parameters. Thus, HTs has the potential to provide functional health benefits in lowering postprandrial hyperglycemia.