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MAH forms maleic acid and esters when dissolved in water and ethanol, respectively, thus creating a mixture in the reaction [ 23]. Previous studies mostly focused on the reaction of MAH with starch and rarely on the reaction of MAH with κCar. Zuo et al. [ 10] reported that MAH modification for starch occurs mainly in the amorphous region of the granule with the maximum degree of substitution (DS) of 0.3386. The availability of -OH groups at C-2, C-3, and C-6 (glucose unit, Mw 162) renders native starch reactive for substitution [ 24]. κCar consists of alternating (1→3)-β- d-galactose-4-sulfate and (1→4)-3,6-anhydro-α- d-galactose residues joined in a linear chain, in which the available -OH groups possess different reactivities for esterification [ 1]. Similar to starch, κCar has an extremely high water-absorbing capacity to react easily. However, κCar has no crystalline region, which means that the water-absorbing capacity of κCar is higher than that of starch. Therefore, κCar has less reactivity than starch, leading to a lower DS. Gel strength is also an important index for κCar. High gel strength is not always the most desirable quality for κCar. However, low strength bestows the product with a stable structure and soft elastic characteristics. κCar with low gel strength has potential uses in liquid food, spread food, soft-texture confectionery, fat replacers, and new industrial applications, and can also serve as a cryoprotectant to minimize the damage of freezing–thawing [ 25, 26]. Thus, the effects of five factors on the DS and gel strength of MC were studied. Prajapati, V. D.,Maheriya, P. M., Jani, G. K., & Solanki, H. K. (2014, May 25). Carrageenan:A natural seaweed polysaccharide and its applications. Carbohydrate Polymers, 105.The joint FAO/WHO Expert Committee on Food Additives (JECFA) have not given carrageenan and processed Eucheuma seaweed a specified an acceptable daily intake (ADI) Mitchell, M.E.; Guiry, M.D. (December 1983). "Carrageen: A local habitation or a name?". Journal of Ethnopharmacology. 9 (2–3): 347–351. doi: 10.1016/0378-8741(83)90043-0. PMID 6677826. The three essential steps of carrageenan extraction using the UAE method are algae pretreatment, carrageenan extraction, and carrageenan purification ( Youssouf et al., 2017). The pretreatment process was started by incubating dried seaweed ( K. alvarezii) in an 80% ethanol solution at room temperature overnight. The pre-treated seaweed was then filtered before being subjected to an ultrasound at 150W for 15min to extract the carrageenan. The movement of ultrasonic waves mediates the extraction process, which results in the transformation of ultrasonic waves into mechanical energy. This mechanical energy then ruptures the cell wall, reducing particle size as a result of the rupture and releasing the carrageenan from the cell wall ( Nigam et al., 2022). Following the extraction process, the carrageenan was available in the form of a solution, and any remaining algal residues were removed using a hot filtering process. It was necessary to place the filter at 4°C for several hours to obtain carrageenan extract in the form of a gel, and gel carrageenan was frozen and lyophilized to obtain the final carrageenan powder ( Youssouf et al., 2017). Ultrasounds allowed for the extraction of 50–55% of carrageenans from red seaweeds such as K. alvarezii and E. denticulatum in 15min, and a longer ultrasonic treatment (30min) may not result in a higher extraction yield ( Youssouf et al., 2017; Azis, 2019). Factors Affecting Carrageenan Yield and Production

Aeni O. N., Aslan L. O. M., Iba W., Patadjai A. B., Rahim M., Balubi M. (2019). Effect of different seedling sources on growth and carrageenan yield of seaweed Kappaphycus alvarezii cultivated in Marobo waters, Muna regency, southeast (se) Sulawesi, Indonesia. IOP Conf. Earth Environ. Sci. 382:012015. doi: 10.1088/1755-1315/382/1/012015 [ CrossRef] [ Google Scholar] Barbeyron T., L’Haridon S., Corre E., Kloareg B., Potin P. (2001). Zobellia galactanovorans gen. Nov., sp. nov., a marine species of Flavobacteriaceae isolated from a red alga, and classific

Buschmann, Alejandro H.; Camus, Carolina; Infante, Javier; etal. (2 October 2017). "Seaweed production: overview of the global state of exploitation, farming and emerging research activity". European Journal of Phycology. 52 (4): 391–406. doi: 10.1080/09670262.2017.1365175. ISSN 0967-0262. S2CID 53640917. Vreeman HJ, Snoeren THM, Payens TAJ (1980) Physicochemical investigation of κ-carrageenan in the random state. Biopolym 19:1357–1374 Arman M, Qader SAU (2012) Structural analysis of kappa-carrageenan isolated from Hypnea musciformis (red algae) and evaluation as an elicitor of plant defense mechanism. Carbohydr Polym 88:1264–1271 Values are mean ± standard deviation. Different lowercase superscripts within the same column indicate significant differences ( p< 0.05).

M. Rustia, P. Shubik and K. Patil, Life span carcinogenicity test with native carrageenan in rats and hamsters, Cancer Lett., 1980, 11(1), 1–10 CrossRef CAS PubMed. Sunset 2018 Review Summary NOSB Final Review" (PDF). USDA Agricultural Marketing Service. 2016-11-30 . Retrieved 2017-02-15. Salinity is another abiotic factor that may influence the carrageenan yields of K. alvarezii because it affects the seaweed’s osmotic equilibrium and nutrient absorption ( Aris et al., 2021). Since carrageenan is essential for maintaining the ionic equilibrium of the cell, it is well recognized that salinity impacts the osmoregulation mechanism, affecting carrageenan yield and quality ( Percival, 1979). However, Setyawidati et al. (2017) reported that the salinity ranges differing between high (33.8–34.8psu) and low (33.0–34.0psu) carrageenan production were only minor, implying that salinity amplitude may be insufficient to explain the variability in carrageenan yield. In contrast, Aris et al. (2021) investigated the effect of different salinity levels (30–34ppt) on the weight of K. alvarezii explants and discovered that the varied salinities affected the growth rate of explants, with the best explant growth occurring at a salinity of 31ppt and the lowest growth occurring at a salinity of 34ppt, respectively. M. L. Weiner, D. Nuber, W. R. Blakemore, J. F. Harriman and S. M. Cohen, A 90-Day Dietary Study on Kappa Carrageenan with Emphasis on the Gastrointestinal Tract, Food Chem. Toxicol., 2007, 45, 98–106 CrossRef CAS PubMed. Cosenza VA, Navarro DA, Fissore EN, Rojas AM, Stortz CA (2014) Chemical and rheological characterization of the carrageenans from Hypnea musciformis (Wulfen) Lamoroux. Carbohydr Polym 102:780–789

Summary

Carrageenans are a family of polysaccharides extracted from red seaweed with water at high temperatures and refined using either an alcohol-precipitation or a gel-press method. International Agency for Research on Cancer (IARC), Monograph, Carrageenan, 1983, vol. 31, pp. 79–94 Search PubMed. Asni A. (2021). Analysis on carrageenan content of seaweed Kappaphycus alvarezii at different water condition in Bantaeng District. IOP Conf. Series Earth Environ. Sci. 860:012069. doi: 10.1088/1755-1315/860/1/012069 [ CrossRef] [ Google Scholar] Van de Velde F, Pereirac L, Rollema HS (2004) The revised NMR chemical shift data of carrageenans. Carbohydr Res 339:2309–2313

A hybrid technology in which seaweed is treated heterogeneously as in the semirefined process exists, but alcohol or high salt levels are used to inhibit dissolution. This process is often used on South American seaweeds and gives some of the cost benefits of semirefined processing, while allowing a wider range of seaweeds to be processed, however, the naturally low cellulose levels in some South American seaweeds allow them to be heterogeneously processed and still be sold under the EU refined specification.

This is only produced from E. cottonii or E. spinosum. The raw weed is first sorted and crude contaminants are removed by hand. The weed is then washed to remove salt and sand, and then cooked in hot alkali to increase the gel strength. The cooked weed is washed, dried, and milled. E. spinosum undergoes a much milder cooking cycle, as it dissolves quite readily. The product is called semi-refined carrageenan, Philippines natural grade, or, in the U.S., it simply falls under the common carrageenan specification. [17] cleaned and washed seaweed M. L. Weiner, Food Additive Carrageenan: Part II: A critical review of carrageenan in vivo, safety studies, Crit. Rev. Toxicol., 2014, 40(3), 244–269 CrossRef PubMed. Zuldin WH, Yassir S, Shapawi R (2016) Growth and biochemical composition of Kappaphycus (Rhodophyta) in customized tank culture system. J Appl Phycol 28:2453–2458