A comparative analysis of phycocolloids produced by underutilized versus industrially utilized carrageenophytes (Gigartinales, Rhodophyta)

Carrageenan (E-407) and semi-refined carrageenan (E-407a) are some of the main additives used by the food industry for their gelling, emulsifying, thickening, and stabilizing properties. These are natural ingredients, which have been used for decades in food applications and are generally regarded as safe. Internationally, sub-tropical carrageenophytes (e.g., Kappaphycus alvarezii) are cultivated extensively as a source of raw materials for industrial extraction, and their use as potential candidates in integrated multitrophic aquaculture is tentative. We analyzed carrageenan yield (as a percentage of dry weight) and chemical composition (by Fourier transform infrared attenuated total reflection and Fourier transform-Raman) of extracts produced by several carrageenophytes (Gigartinales, Rhodophyta), from different origins, e.g., K. alvarezii (Tanzania, Indonesia, the Philippines, Panama, and Mexico), Kappaphycus striatum (Madagascar), Eucheuma denticulatum (Tanzania, the Philippines, and Madagascar), Betaphycus gelatinum (the Philippines), Chondracanthus chamissoi, and Sarcothalia crispata (Chile). For comparison, some underutilized carrageenophytes were also analyzed, e.g., Chondrus crispus, Mastocarpus stellatus, Gigartina pistillata, Chondracanthus teedei var. lusitanicus, Chondracanthus acicularis, Calliblepharis jubata, Gymnogongrus crenulatus, and Ahnfeltiopsis devoniensis (Portuguese carrageenophytes). The main findings were that the highest carrageenan yield was obtained from K. striatum (Madagascar) with 75.6 (percent dry weight (% DW)); B. gelatinum and K. alvarezii (both from the Philippines) had yields of 71.0% and 68.0% (% DW), respectively; and G. pistillata (Portugal) 65.4% (% DW). Spectroscopic analysis of the phycocolloids allowed determination of a wide range of carrageenan types, e.g., pure iota carrageenan, several kappa–iota hybrid carrageenans with different iota/kappa ratios, and kappa–beta, xi–theta, and xi–lambda hybrid carrageenans.