Stuthmann, Lara ORCID: https://orcid.org/0000-0002-0106-7026, Achuthan, Revathi, Pribbernow, Mia, Du, Hoang Trung, Springer, Karin and Kunzmann, Andreas ORCID: https://orcid.org/0000-0002-9500-4332 (2022) Improving the nutritional value of edible Caulerpa lentillifera (Chlorophyta) using high light intensities. A realistic tool for sea grape farmers. Algal Research, 66 . p. 102785. DOI https://doi.org/10.1016/j.algal.2022.102785.

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Abstract

Edible sea grapes (Caulerpa lentillifera) are produced in shaded ponds (~ 50 μmol photons m−2 s−1) and are of increasing demand for direct human consumption. The controlled exposure to light-stress after harvest could increase algae's content of nutritionally valuable antioxidants, including phenols. In order to define a light-stress tool for farmers to use, we investigated the effect of five irradiances (50–600 μmol photons m−2 s−1) for an exposure time of up to 14 days. Antioxidant activity (AOA, initial of 150.93 ± 25.50 mmol Trolox equivalents 100 g−1 DW) and total phenolic content (TPC, initial of 124.45 ± 10.07 mg Gallic acid equivalents 100 g−1 DW) significantly increased to values of up to 228.8 ± 12.4 and 222.2 ± 22.7 % of initial, respectively. However, targeted increases in antioxidant parameters correlated with decreased values of Fv/Fm (p < 0.001) and the chlorophyll (Chl) a content in the edible frond was significantly lower at irradiances ≥400 μmol photons m−2 s−1 compared to the control (50 μmol photons m−2 s−1), causing bleaching. As the physiological response of the alga (Fv/Fm, AOA, TPC, Chl a) depended on exposure time and irradiance treatment, both parameters could be adjusted to define treatments according to the consumer's needs. Light irradiances measured at a sea grape farm revealed that farmers could integrate such treatments labour- and cost-effectively by removing layers of plastic-meshes off their culture or post-harvest units. The pattern of Chl a loss and red (R) colour channel values in sea grapes thallus parts implied, that a combination of degradation and chloroplast migration was responsible for bleaching at light-stress. Additionally, R channel values extracted from pictures could be used for Chl a estimation, due to strong correlation (rS = −0.786, p < 0.001). In conclusion farmers can use high light as post-harvest treatment in order to increase valuable antioxidants.

Document Type:	Article
Programme Area:	PA1
Research affiliation:	Ecology > Experimental Aquaculture
Refereed:	Yes
Open Access Journal?:	No
DOI:	https://doi.org/10.1016/j.algal.2022.102785
ISSN:	22119264
Date Deposited:	25 Jul 2022 13:47
Last Modified:	25 Jul 2022 13:47
URI:	http://cris.leibniz-zmt.de/id/eprint/4994

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