Impact of alkali pretreatment on yield, physico-chemical and gelling properties of high quality agar from Gracilaria tenuistipitata

Wang, Lianjie; Shen, Zhaopeng; Mu, Huimin; Lin, Yue; Zhang, Jingliang; Jiang, Xiaolu

doi:10.1016/j.foodhyd.2016.11.042

Cited by 48 publications

(26 citation statements)

References 30 publications

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“…When alkaline pretreatment with NaOH and KOH at the concentration range of 3-7% were used for Gracilaria tenuistipitata, respectively, the high-quality agar with yield ranging from 23.6-26.1% was obtained, and gel strength increased by 77.5-80.4% (419-482 g/cm 2 ) and 76.7-78.8% (406-446 g/cm 2 ), respectively. Wang et al [15] found that 6% alkali treatment at 80 • C for 1.5 h was the optimal pretreatment process for extracting high-quality agar from Gracilaria tenuistipitata; the process resulted in a gel strength of 1068.15 g/cm 2 and high yield of 23.14%, which are higher than previous reports. However, in the current industrial practice of agar extraction, alkali treatment is only one of the many pre-treatment processes [8].…”

Section: Introductionmentioning

confidence: 81%

Pretreatment Techniques and Green Extraction Technologies for Agar from Gracilaria lemaneiformis

et al. 2021

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Optimizing the alkali treatment process alone without tracking the changes of algae and agar quality with each pretreatment process will not achieve the optimal agar yield and final quality. In this study, we monitored the changes of the morphology and weight of algae with each treatment process, and comprehensively analyzed the effects of each pretreatment process on the quality of agar by combining the changes of the physicochemical properties of agar. In conventional alkali-extraction technology, alkali treatment (7%, w/v) alone significantly reduced the weight of algae (52%), but hindered the dissolution of algae, resulting in a lower yield (4%). Acidification could solve the problem of algal hardening after alkali treatment to improve the yield (12%). In enzymatic extraction technology, agar with high purity cannot be obtained by enzyme treatment alone, but low gel strength (405 g/cm2) and high sulfate content (3.4%) can be obtained by subsequent acidification and bleaching. In enzyme-assisted extraction technology, enzyme damage to the surface fiber of algae promoted the penetration of low-concentration alkali (3%, w/v), which ensured a high desulfurization efficiency and a low gel degradation rate, thus improving yield (24.7%) and gel strength (706 g/cm2), which has the potential to replace the traditional alkali-extraction technology.

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Section: Introductionmentioning

confidence: 81%

Pretreatment Techniques and Green Extraction Technologies for Agar from Gracilaria lemaneiformis

et al. 2021

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“…More importantly, this seaweed is used in the agar industry as a raw material because of its high polysaccharide content [5, 6]. In current agar production, dried seaweed is used as a raw material to produce agar via several methods including alkali pretreatment or acid hydrolysis [7, 8], and the volatile constituents (VCs) of G. lemaneiformis are destroyed and discarded as waste. The VCs of G. lemaneiformis are reported to exhibit cytotoxic activity and tyrosine phosphatase 1B inhibitory activity [9, 10], suggesting that these VCs could be useful in the food, cosmetic, and pharmaceutical industries [11, 12].…”

Section: Introductionmentioning

confidence: 99%

A sustainable process for the recovery of volatile constituents from Gracilaria lemaneiformis in agar production and evaluation of their antioxidant activities

Yuan

Duan

et al. 2019

BMC Chemistry

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Background Gracilaria lemaneiformis is a common red alga used as a raw material source for the agar industry. Its extract is rich in natural volatile constituents (VCs) having antioxidant activities. Herein, a sustainable method was used to recover VCs from the alga. The chemical composition of VCs present in the n -hexane fraction was analyzed by gas chromatography–mass spectroscopy (GC–MS) and the antioxidant potential was measured using a series of in vitro biochemical assays, including DPPH, hydroxyl, and superoxide radical scavenging assays. Results The recovery yield of the VCs was 0.823 wt% of the dry mass of G. lemaneiformis . A total of 25 VCs were successfully identified, comprising approximately 99.94% of the total volume. The major component was n -hexadecanoic acid (38.57%), followed by oleic acid (25.48%), arachidonic acid (12.84%), and tetradecanoic acid (2.52%). In addition, The VCs displayed strong free radical scavenging activity in the DPPH (IC 50 = 21.56 mg/L), hydroxyl (IC 50 = 18.34 mg/L), and superoxide (IC 50 = 391.12 mg/L) radical scavenging assays. The antioxidant activities of the VCs exhibited a dose-dependence at concentrations ranging from 5 to 200 mg/L. Conclusion The results indicated that the sustainable process improved the agar quality and that the extract contained many natural VCs with antioxidant activities, which have the potential to be used in functional food and cosmetics instead of as a discarded byproduct of the agar industry.

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“…Agar is the main matrix component of cell walls of some red algae such as Gracilaria sp., applicable as gelling agent, stabilizing agent, and cryoprotectants in processed foods, cosmetics and pharmaceutical products [7,8]. Agar obtaining process from Gracilaria sp.…”

Section: Introductionmentioning

confidence: 99%

Economic evaluation and comparison of two topologies for agar production from red algae

González-Delgado¹,

León-Pulido²,

Peralta-Ruiz³

2018

ces

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Macroalgae have been one of the main source of raw material for different products involved in food technology, biotechnology, microbiology and medicine due to its abundance, diversity and economic value, in fact some of these are being used as a direct source of agar. There are different routes for agar extraction at industrial scale, so it is of great importance to determine economic viability of these in order to select the process that offers greater profitability under defined criteria. In this paper, an economic evaluation was performed to compare two routes for obtaining agar: freeze-thaw (Route 1) and evaporation (Route 2) considering to Colombia for plant location. The effect of raw material cost and plant location on profitability of both routes was also evaluated through sensibility analysis. From economic evaluation, it was found that these routes are possible in terms techno-economic; however, Route 2 has a higher profitability due to its lower fixed capital, operating and utilities costs.

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Impact of alkali pretreatment on yield, physico-chemical and gelling properties of high quality agar from Gracilaria tenuistipitata

Cited by 48 publications

References 30 publications

Pretreatment Techniques and Green Extraction Technologies for Agar from Gracilaria lemaneiformis

Pretreatment Techniques and Green Extraction Technologies for Agar from Gracilaria lemaneiformis

A sustainable process for the recovery of volatile constituents from Gracilaria lemaneiformis in agar production and evaluation of their antioxidant activities

Economic evaluation and comparison of two topologies for agar production from red algae

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