Summary
Edible oils industry is using synthetic and natural antioxidants to enhance the oxidative stability of bulk edible oils. Due to safety concerns of BHA, BHT and TBHQ, there is an ongoing ...effort to find an effective and safe replacement. Finding a safe antioxidant or its synergistic mixture, which delays, retard or prevent the oxidation of bulk oil without changing the colour or flavour upon addition is a challenge. In this review, a brief account of chemical basis of oxidative deterioration of the stored oil is given. The effectiveness of most widely experimented antioxidants such as tocopherols, carotenoids, ascorbic acid and its derivatives, lignan compounds, flavonoids, polyphenols and phenolic acids in various edible oils have been reviewed. Further, the synergistic and antagonistic combination of these antioxidants in controlling oxidative degradation of edible oils has been discussed.
Role of antioxidants in enhancing oxidative stability of bulk edible oils.
Summary
Areca nut (pericarp of Areca catechu L.) is a rich source of valuable phenolic compounds. Presence of a psychoactive agent, Arecoline, pose a challenge in the use of areca nut extracts. With ...an aim to maximise the extraction of phenolic compounds, a newly isolated Rhizopus orizae MW538932, was employed for the solid‐state fermentation of unripe areca nut (6–7 months' maturity) powder. Supplementary nutrients (carbon and nitrogen sources) for the media and the solvents for the extraction of phenolic compounds from the fermented medium were optimised. The optimised process could produce an extract having a total phenolic content of 186.03 ± 2.50 mg gallic acid equivalent and total flavonoid content of 139.70 ± 2.00 mg catechin equivalent per gram of the sample. UHPLC–MS/MS studies and HPLC analysis showed the presence of plethora of phenolic compounds and the absence of Arecoline and other alkaloids. This flavonoid‐rich extract can be a potential source of natural antioxidants for food and pharmaceutical industry.
Fermentative extraction of phenolic compunds from unripe areca nuts.
Summary
The major sources of dietary lipids are edible oils, which include both vegetable and fish oils. Crude oil extracted from vegetable and fish sources contain mono‐, di‐, triacylglycerols along ...with impurities, which necessitates refining. The main objective of refining is to remove the contaminants that adversely affect the quality of oil, thereby reducing the shelf life and consumer acceptance. However, this refining process needs to be tailored as the composition of crude oil is highly variable, depending upon the plant/fish species, geographical location of the source and method of oil extraction. Recently, extensive efforts have been made to develop refining technology, using either conventional physical/chemical processes or several unconventional processes including biological and membrane processes. The first section of this review gives a brief description of general composition of some commonly used vegetable and fish oils, followed by the review of various refining methods and their effects on the oil constituents. Finally, an effort is made to understand the technological gaps in the existing methods and possible directions of research to overcome the said gaps.
Edible oil is refined in industry typically through four steps viz., degumming, deacidification, bleaching and deoderization, and each step in turn may employ one or more technologies to accomplish the desired task. This figure summarizes all the existing and potential technologies available for refining the edible oil.
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•Three esters of 3,4-dihydroxyphenylacetic acid (DHPA) were synthesized.•Binary solvent system with Amberlyst-15 was used to synthesize esters.•Esters were subjected to In vitro ...antioxidant assays and oil storage study.•Methyl ester showed higher efficacy relative to butyl and hexyl esters in bulk oil.•Esters performance in bulk oil system was compliant with polar paradox theory.
Lipophilization of natural antioxidants is a proven strategy to enhance the solubility in bulk oil systems, thereby increasing their efficacy against oxidative degradation. This study aims to synthesize esters of 3,4-dihydroxyphenylacetic acid (3,4-DHPA) using Amberlyst-15 and to study the application of these esters in refined fish oil. Lipophilic esters were synthesized by esterification and transesterification of 3,4-DHPA in various solvent systems. Esters of methanol, butanol and hexanol were obtained with percent conversion of 81.1, 69.3 and 78.8 respectively, and were subjected to molecular characterization and in vitro oxidant assays. The 3,4-DHPA and its methyl ester showed 36% reduction in the TOTOX value over 30 days of storage. The length of the acyl chain in the ester was found to exert a high influence on its efficacy and lipophilicity. This is the first report of 3,4-DHPA and its lipophilic esters studied for enhancing the oxidative stability of fish oil.
l-Asparaginase is one of the main drugs used in the treatment of acute lymphoblastic leukemia (ALL), a commonly diagnosed pediatric cancer. Although several microorganisms are found to produce ...l-asparaginase, only the purified enzymes from E. coli and Erwinia chrysanthemi are employed in the clinical and therapeutic applications in humans. However, their therapeutic response seldom occurs without some evidence of hypersensitivity and other toxic side effects. l-Asparaginase is also of prospective use in food industry to reduce the formation of acrylamide in fried, roasted or baked food products. This review is an attempt to compile information on the properties of l-asparaginases obtained from different microorganisms. The complications involved with the therapeutic use of the currently available l-asparaginases, and the enzyme's potential application as a food processing aid to mitigate acrylamide formation have also been reviewed. Further, avenues for searching alternate sources of l-asparaginase have been discussed, highlighting the prospects of endophytic microorganisms as a possible source of l-asparaginases with varied biochemical and pharmacological properties.
Free-CRL and CRL-CLEA were compared for their efficiency in hydrolyzing the ester bonds of glycerides other than the ones having n-3 PUFA acyl chain. Preparation of CRL-CLEA from free-CRL is depicted ...here.
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•CLEA was prepared from bioimprinted Candida rugosa lipase, BSA and PEI.•Preparation of CLEA was optimized and properties were studied.•CLEA thus prepared, showed higher degree of hydrolysis and thermal stability.•Hydrolysis with CRL-CLEA resulted in 2.83 fold increase in n-3 PUFA content.•Reusability studies showed, CRL-CLEA could be efficiently reused upto 5 runs.
Considering the advantages of bioimprinting and carrier free immobilization, cross-linked enzyme aggregates (CLEA) were prepared by using bioimprinted Candida rugosa lipase (CRL) with Bovine serum albumin (BSA), Polyethyleneimine and glutaraldehyde. Effect of various factors such as CRL-Oleic acid ratio, CRL-BSA ratio, CRL- Polyethyleneimine ratio, glutaraldehyde loading, cross-linking time etc., on lipase activity recovery and aggregate yield were studied and optimized. This immobilized lipase (CRL-CLEA) was used for the selective hydrolysis of ester linkages of non-PUFA glycerides, with an aim to concentrate EPA and DHA glycerides in the Sardine oil. Imprinting with oleic acid in the presence of ethanol and Tween 60, and further immobilization with co-aggregates and cross-linking agent showed 10.4 times higher degree of hydrolysis compared to free enzyme. As result, 2.83-fold increase of n-3 PUFA content in deacidified oil was obtained by using CRL-CLEA. The resultant oil had negligible di- and triglycerides content, proving higher efficiency in hydrolysing ester bonds of fatty acids, other than n-3 PUFA. Reusability studies showed CRL-CLEA could be reused up to 5 runs without a substantial reduction in its performance. Improvement in degree of hydrolysis, thermostability, efficiency of hydrolysis and reusability were achieved due to bioimprinting and subsequent immobilization of CRL in the form of CLEA.
Summary
Chrysin is a hydrophobic flavonoid with multiple health benefits. The various applications of chrysin are challenged by its poor solubility, instability and loss of bioactivity. ...Casein–chrysin complex and casein–polysaccharide–chrysin complexes have developed to overcome these limitations. Very high encapsulation efficiency of 98.23 ± 0.22% was achieved with casein–inulin–chrysin complex. The chrysin was able to form a stable casein–polysaccharide–chrysin complex suspension with a hydrodynamic diameter of 382.3 nm, zeta potential value of −12.3 mV and a Polydispersity Index (PDI) of 27.7. The antioxidant activity of chrysin increased about threefold after encapsulation. The release of chrysin from its encapsulated complexes to different buffers in the pH range of 3 to 10 was studied at 1:10 ratio. At the end of 48 h, only 6%–8% of chrysin was released in the pH range 3–4, 33%–58% at pH 5–9 and 62% at pH 10. The chrysin encapsulated in casein–inulin–chrysin complex was able to overcome the rapid release of chrysin from the casein–chrysin complex. The results indicate the successful development of a stable encapsulated chrysin complex which can overcome the various limitations of chrysin in its potential applications.
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•First report on characterization of l-asparaginase from an endophytic fungus.•The enzyme is stable over a good range of pH and temperature.•The enzyme is a heterodimer of 61.9kDa and ...39.1kDa.•The enzyme has a turnover number of 286.26s−1.•Cysteine residues play critical role in catalysis.
l-Asparaginase is a commercially significant enzyme. There exists a demand for a broad variety of microbial l-asparaginases with characteristics compatible with its different applications. Endophytic microorganisms, in particular are emerging as potential sources of l-asparaginases.
The current work involves partial purification and characterization of l-asparaginase from Talaromyces pinophilus, an endophytic fungus isolated from the rhizomes of Curcuma amada. Maximum enzyme activity could be achieved at pH 8.0 and with temperature 28°C. The enzyme Exhibits 95 % and 98% of its total activity at physiological pH and temperature, respectively. The enzyme activity is largely unhindered in the presence of metal ions such as Ca2+, Cu2+, Fe2+, Mg2+, Mn2+, Zn2+. Increase in the enzyme activity in the presence of thiol groups and reduction in the same upon addition of thiol blockers indicates the involvement of cysteine in the enzyme’s catalytic activity. The enzyme is a heterodimer of 62kDa and 39kDa. The enzyme has a Km of 6.4mM, its turnover number towards l-asparagine is 286.3s−1. The enzyme has 16% glutaminase activity; its Km towards glutamine is 13.3mM and turnover number is 54.6s−1.
Our results highlight that l-asparaginase from endophytic Talaromyces pinophilus could be considered as potential candidate for clinical and industrial trials, owing to its efficiency and biochemical properties. To the best of our knowledge, this is the first report on partial purification and characterization of L-asparaginase from an endophyte.
Summary
Poor oxidative stability exhibited by n‐3 polyunsaturated fatty acid rich sardine oil is a major challenge for its utilisation in industry. Considering the fact that water is always present ...in bulk oil in trace amounts during storage, an effort was made to understand and compare the effectiveness of rutin and its corresponding lipophilic ester in enhancing oxidative stability of refined sardine oil containing trace water (0.16% w/w). Peroxide value, conjugated diene value, p‐anisidine value and thiobarbituric acid reactive substances (TBARS) value were determined during 20 days storage. Rutin fatty ester showed 50% reduction in primary oxidation and 42.46% reduction in secondary oxidation, whereas rutin showed 20.6% and 20.43% reduction in primary and secondary oxidation, respectively, by the end of 20 days storage. Thus, it is clearly established that rutin fatty ester is more effective than hydrophilic rutin in sardine oil containing trace water, which contradicts the polar paradox theory.
Effectiveness of rutin and rutin fatty ester in reducing peroxide value and TBARS value in sardine oil..
A novel process comprising treatment of Taro (Colocasia esculenta (L.) Schott) tuber flour with oxalate oxidase enzyme is developed to deplete the oxalate content. Oxalate oxidase enzyme produced by ...an endophyte, Ochrobactrum intermedium CL6 is employed to treat taro tuber flour. The treatment followed by extraction of starch results in a 97% reduction in total oxalate content. Further, several physicochemical properties such as paste clarity, swelling power, solubility, amylose content, granule size of starch produced out of enzyme treatment are studied and compared with properties of taro starch produced without enzyme treatment. The study reveals that enzyme treatment does not bring appreciable changes in the studied parameters. The taro starch produced by enzyme treatment shows very low paste clarity (9.38%), high swelling power (15.32 g/g), very low solubility (21.66%), and low amylose content (7.52%) at 100 °C compared to potato and sweet‐potato starches. X‐ray diffraction data reveal that taro starch possesses an A‐crystalline form, unlike the B‐crystalline form found in potato and sweet potato starch. To the best of the authors knowledge, for the first time, the use of oxalate oxidase to produce oxalate depleted taro starch is reported. One of the interesting food industry applications of oxalate‐depleted taro starch, among many other uses could be for baby food formulation because of its small granule size.
For the first time, oxalate oxidase is used in Taro tuber processing to reduce oxalate content. This novel process could eliminate 97% of total oxalate content in Taro starch. The physicochemical properties of starch remain unaltered after enzyme treatment.
