Harvesting Stage Regulates the Rheological, Colour and Chemical Properties of Gracilaria changii Agar
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Abstract
Gracilaria changii is a red seaweed with significant economic potential and has emerged as a promising species for industrial agar production. Despite its commercial importance, limited information is available regarding the influence of harvesting stage on the physicochemical and rheological quality of agar extracted from G. changii. Since this seaweed exhibits an isomorphic life cycle that is completed within approximately 30 days–90 days, variations in harvesting stage may significantly affect agar composition and functionality. Thus, identifying the optimal harvesting stage is essential for producing high-quality agar suitable for industrial use. This study evaluated the effect of different harvesting stages; Stage I (30 days–40 days), Stage II (40 days–50 days) and Stage III (60 days and above). Seaweed at different harvesting stages were then subjected to alkaline pretreatment followed by hot-water agar extraction. The extracted agar was evaluated for rheology, colour and chemical properties. This study revealed that stage I was the optimal harvesting stage since the agar had the best rheological properties with high agar yield (7.36%), high transparency (53.39%), low gel syneresis (1.64%) and the highest gel strength (299.94 g/cm2) as compared to other stages. Agar extracted from Stages I and II exhibited a more intense red-brown colour than agar obtained from Stage III. In addition, the Stage I agar had a low total sulphate content (4.58%) and a high 3,6-anhydrogalactose content (13.33%), which contribute to low syneresis and excellent gel strength. The finding from this study could be used as standard cultivation practices for both cultivator and marketer to standardise the agar quality that meet the industrial specifications.
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Al-Nahdi Z M, Al-Alawi A, Al-Marhobi I and Al-Zefiti A. (2015). Optimization of yield and chemical properties of agar extracted from Melanothamnus somalensis from Oman Sea. Journal of Environmental Science and Engineering B 4: 302–314. https://doi.org/10.17265/2162-5263/2015.06.002
An D, Xiao Q, Zhang C. Cai M, Zhang Y, Weng H, Chen F and Xiao A. (2021). Preparation, characterization, and application of high-whiteness agar bleached with hydrogen peroxide. Food Hydrocolloids 113(8): 106520. https://doi.org/10.1016/j.foodhyd.2020.106520
Bokhtiar S M, Ali M A, Chowdhury M A Z, Ahmed K U, Hassan, M K, Ahmed M, Bhuiyan M S, Mashuk O F, Rahman M M, Salam M A, Rafiquzzaman S M and Hossain M F. (2022). Yield improvement of Gracilaria tenuistipitata by optimizing different aspects in coast of Cox’s Bazar, Bangladesh. Scientific Reports 12(1): 1–8. https://doi.org/10.1038/s41598-022-11718-3
Chen H, Xiao Q, Weng H, Zhang, Y, Yang Q and Xiao A. (2020). Extraction of sulfated agar from Gracilaria lemaneiformis using hydrogen peroxide-assisted enzymatic method. Carbohydrate Polymers 232(7): 115790. https://doi.org/10.1016/j.carbpol.2019.115790
Charoenrein S and Owcharoen K. (2016). Effect of freezing rates and freeze-thaw cycles on the texture, microstructure and pectic substances of mango. International Food Research Journal 23(2): 613–620. http://www.ifrj.upm.edu.my
Chumsook K, Praiboon J and Fu X. (2023). Sulfated galactans from agarophytes: Review of extraction methods, structural features, and biological activities. Biomolecules 13(12): 1745. https://doi.org/10.3390/biom13121745
Freile-Pelegrín Y and Murano E. (2005). Agars from three species of Gracilaria (Rhodophyta) from Yucatán Peninsula. Bioresource Technology 96(3): 295–302. https://doi.org/10.1016/j.biortech.2004.04.010
Khoobbakht F, Khorshidin S, Bahmanyar F, Hosseini S M, Aminikhah N, Farhoodi M and Mirmoghtadaie L. (2024). Modification of mechanical, rheological and structural properties of agar hydrogel using xanthan and locust bean gum. Food Hydrocolloids 147: 109411. https://doi.org/10.1016/j.foodhyd.2023.109411
Lee W K, Lim P E, Phang S M, Namasivayam P and Ho C L. (2016). Agar properties of Gracilaria species (Gracilariaceae, Rhodophyta) collected from different natural habitats in Malaysia. Regional Studies in Marine Science 7: 123–128. https://doi.org/10.1016/j.rsma.2016.06.001
Lee W K, Lim Y Y and Ho C L. (2019). pH affects growth, physiology and agar properties of agarophyte Gracilaria changii (Rhodophyta) under low light intensity from Morib, Malaysia. Regional Studies in Marine Science 30: 100738. https://doi.org/10.1016/j.rsma.2019.100738
Li Y, Zhao M, Gomez L P, Senthamaraikannan R, Padamati R B, O’Donnell C P and Tiwari B K. (2021). Investigation of enzyme-assisted methods combined with ultrasonication under a controlled alkali pretreatment for agar extraction from Gelidium sesquipedale. Food Hydrocolloids 120(5): 106905. https://doi.org/10.1016/j.foodhyd.2021.106905
Lim Y Y, Lee W K, Lim P E, Phang S M, Leow A T C, Namasivayam P, Abdullah J O and Ho C L. (2019). Expression analysis of potential transcript and protein markers that are related to agar yield and gel strength in Gracilaria changii (Rhodophyta). Algal Research 41(4): 101532. https://doi.org/10.1016/j.algal.2019.101532
Lin H T V, Tsai J S, Liao H H and Sung W C. (2023). The effect of hydrocolloids on penetration tests and syneresis of binary gum gels and modified corn starch–gum gels. Gels 9(8): 605. https://doi.org/10.3390/gels9080605
Lomartire S and Gonçalves A M M. (2023). Algal phycocolloids: Bioactivities and pharmaceutical applications. Marine Drugs 20(7): 1–30. https://doi.org/10.3390/md21070384
Maleki N, Roomiani L and Tadayoni M. (2023). Microwave-assisted extraction optimization, antimicrobial and antioxidant properties of carrageenan from red algae (Gracilaria acerosa). Journal of Food Measurement and Characterization 17(2): 1156–1166. https://doi.org/10.1007/s11694-022-01682-x
Martínez-Sanz M, Gomez-Barrio L P, Zhao M, Tiwari B, Knutsen S H, Ballance S, Zobel H K, Nilsson A E, Krewer C, Ostergren K and Lopez-Rubio A. (2021). Alternative protocols for the production of more sustainable agar-based extracts from Gelidium sesquipedale. Algal Research 55: 102254. https://doi.org/10.1016/j.algal.2021.102254
Martínez-Sanz M, Gómez-Mascaraque L G, Ballester A R, Martínez-Abad A, Brodkorb A and López-Rubio A. (2019). Production of unpurified agar-based extracts from red seaweed Gelidium sesquipedale by means of simplified extraction protocols. Algal Research 38(10): 101420. https://doi.org/10.1016/j.algal.2019.101420
Mohibbullah M, Talha M A, Baten M A, Newaz A W and Choi J S. (2023). Yield optimization, physicochemical characterizations, and antioxidant properties of food grade agar from Gracilaria tenuistipitata of Cox’s Bazar coast, Bangladesh. Food Science & Nutrition 11(6): 2852–2863. https://doi.org/10.1002/fsn3.3265
Nor S M, Ding P and Chun T J. (2023). Locule position and thawing duration affect postharvest quality of freshly cryo-frozen Musang King Durian fruit. Pertanika Journal of Tropical Agricultural Science 46(2): 517–528. https://doi.org/10.47836/pjtas.46.2.09
Othman M N A, Hassan R, Harith M N and Md Sah A S R. (2018). Morphological characteristics and habitats of red seaweed Gracilaria spp. (Gracilariaceae, Rhodophyta) in Santubong and Asajaya, Sarawak, Malaysia. Tropical Life Sciences Research 29(1): 87–101. https://doi.org/10.21315/tlsr2018.29.1.6
Radulovich R, Neori A, Valderrama N, Reddy C R K, Reddy H C and John F. (2015). Farming of seaweeds. In B K Tiwari and D J, Troy (eds.), Seaweed sustainability. food and non-food applications, Elsevier, 27–59. https://doi.org/10.1016/B978-0-12-418697-2.00003-9
Rahim N F A, Muhammad N and Abdullah N. (2022). Optimum extraction condition of Anacardium occidentale on antiurolithiatic activities (in-vitro). Sains Malaysiana 51(4): 1099–1109. https://doi.org/10.17576/jsm-2022-5104-12
Sade A, Ali I and Ariff M R M. (2006). The seaweed industry in Sabah, East Malaysia. Jati: Journal of Southeast Asian Studies 11: 97–107.
Sasuga K, Yamanashi T, Nakayama S, Ono S and Mikami K. (2017). Optimization of yield and quality of agar polysaccharide isolated from the marine red macroalga Pyropia yezoensis. Algal Research 26(4): 123–130. https://doi.org/10.1016/j.algal.2017.07.010
Suhaimai N N, Zainuldin F N A, Kassim J and Nor S M. (2025). Morphology and nutritional composition of Gracilaria changii at different maturation stages. Pertanika Journal of Tropical Agricultural Science 48(4): 1337–1353. https://doi.org/10.47836/pjtas.48.4.15
Steinhagen S, Enge S, Cervin G, Larsson K, Edlund U, Schmidt A E M, Wahistrom N, Kollander B, Pavia H, Undeland I and Toth G B. (2022). Harvest time can affect the optimal yield and quality of Sea lettuce (Ulva fenestrata) in a sustainable sea-based cultivation. Frontiers in Marine Science 9(2): 816890. https://doi.org/10.3389/fmars.2022.816890
Torres M D, Flórez-Fernández N and Domínguez H. (2019). Integral utilization of red seaweed for bioactive production. Marine Drugs 17(6): 314. https://doi.org/10.3390/md17060314
Trongnit J, Mayakun J and Kaewtatip K. (2024). The effect of agar from the seaweed Gracilaria fisheri on properties of biodegradable starch foam. International Journal of Biological Macromolecules 273(1): 132952. https://doi.org/10.1016/j.ijbiomac.2024.132952
Vuai S A H. (2022). Characterization of agar extracted from Gracilaria species collected along Tanzanian Coast. Heliyon 8(2): e09002. https://doi.org/10.1016/j.heliyon.2022.e09002
Wang L, Shen Z, Mu H, Lin Y, Zhang J and Jiang X. (2017). Impact of alkali pretreatment on yield, physico-chemical and gelling properties of high quality agar from Gracilaria tenuistipitata. Food Hydrocolloids 70: 356–362. https://doi.org/10.1016/j.foodhyd.2016.11.042
Xiao Q, Weng H, Ni H, Hong Q, Lin K and Xiao A. (2019). Physicochemical and gel properties of agar extracted by enzyme and enzyme-assisted methods. Food Hydrocolloids 87(7): 530–540. https://doi.org/10.1016/j.foodhyd.2018.08.041
Yaphe W and Arsenault G P. (1965). Improved resorcinol reagent for the determination of fructose, and of 3,6-anhydrogalactose in polysaccharides. Analytical Biochemistry 13(1): 143–148. https://doi.org/10.1016/0003-2697(65)90128-4
Yarnpakdee S, Benjakul S and Kingwascharapong P. (2015). Physico-chemical and gel properties of agar from Gracilaria tenuistipitata from the lake of Songkhla, Thailand. Food Hydrocolloids 5: 217–226. https://doi.org/10.1016/j.foodhyd.2015.05.004
Zhang C, An D, Xiao Q, Weng H, Zhang Y, Yang Q and Xiao A. (2020). Preparation, characterization, and modification mechanism of agar treated with hydrogen peroxide at different temperatures. Food Hydrocolloids 101(10): 105527. https://doi.org/10.1016/j.foodhyd.2019.105527