Browsing by Author "Belur, Prasanna D."

Now showing 1 - 2 of 2

Studies on Fermentative Extraction of Antioxidants from Unripe Areca Nut
(National Institute of Technology Karnataka, Surathkal, 2024) Hugar, Priyanka N.; Belur, Prasanna D.; Regupathi, I.
The pericarp of Areca catechu L., commonly known as areca nut, contains a wealth of valuable phenolic compounds. The presence of the psychoactive agent Arecoline can make it challenging to utilize these compounds. To address this issue, current research work was aimed at isolating a microorganism that can grow on areca nut and facilitate the extraction of valuable phenolic compounds. Two organisms, a mold and yeast, were isolated from the microbial mat growing on the stored areca extract leachate surface. The mold was identified as Rhizopus oryzae MW538932 and yeast as Geotrichum cucujoidarum MW538971. Based on HPLC-MS/MS analysis and MetFrag search engine, major components in chogaru (unripe areca nut extract) were identified as Arecatannin B1 and Procyanidin B4/B5 which were being used by the mold and yeast as their primary carbon sources. However, the mold was found to be more efficient at utilizing these compounds than the yeast, which led to it being selected for further research. Shake flask studies indicated that the isolate, Rhizopus oryzae MW538932 mold was converting Arecatannin B1 to Procyanidin B, which was then further converted to Catechin and Protocatechuic acid (PCA). Similarly, Procyanidin B4/B5 was converted to Catechin and PCA. In order to maximise the extraction of phenolic compounds, the isolated mold Rhizopus oryzae 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. The media for the fermentative extraction of phenolic components by the SmF process was optimized using the Plackett-Burman design and RSM. The optimised process could produce an extract having a total phenolic content of 146.06 ± 0.75 mg gallic acid equivalent and a total flavonoid content of 53.74 ± 0.83 mg catechin equivalent per gram of the sample. UHPLC-MS/MS studies and HPLC analysis revealed a wide range of phenolic compounds found exclusively in fermented extracts and decreased Arecoline content by 28.57%. A comparative study of the antioxidant properties of the extracts produced by SSF and SmF showed that fermented extracts had better antioxidant potential than unfermented extracts. The light brown colored lyophilized powder free from arecoline, obtained by the fermentative extraction of unripe areca nuts by SSF was analyzed for its efficacy in imparting oxidative stability to the fish oil. The total phenolic and flavonoid contents of the fermented extract were 10.41 ± 0.81 mg gallic acid equivalent and 7.58 ± 1.01 mg catechin equivalent per mg of the powder respectively. The DPPH radical scavenging activity and FRAP were 0.23 ± 0.01 and 0.064 ± 0.02 mmol Trolox equivalent per mg, respectively. UHPLC-MS/MS analysis revealed the presence of more than 45 different phenolic compounds. It exhibited superior efficacy in imparting oxidative stability to the n-3 PUFA containing fish oil in 50 days of storage studies. Its performance was comparable to BHT for the initial 25 days of storage. This could be a new addition to well-proven herbal extracts such as rosemary extract and green tea extracts for food application.
Study of Oxidative Stability of Sardine Oil in the Presence of Antioxidants
(National Institute of Technology Karnataka, Surathkal, 2023) Mishra, Sumit Kumar; Belur, Prasanna D.; Regupathi, I.
The Indian sardine fish (Sardinella longiceps) oil is highly valued for its affordability and abundance as a source of n-3 polyunsaturated fatty acids (n-3 PUFA), which includes the beneficial eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). These compounds have positive effects on the prevention and treatment of various health conditions, such as coronary, neuromuscular, immunological, and allergic disorders. However, it is important to note that the n-3 PUFA contains many -C=C- double bonds, which are susceptible to oxidation due to their low bond dissociation energies (80kcal/mol). This oxidation process produces primary (hydroperoxide) and secondary oxidation (aldehydes and ketones) products that can result in an unpleasant taste. The extrinsic and intrinsic factors that contribute to the oxidation process, such as light, temperature, degree of saturation, free fatty acids, phospholipids, and pigments, leading to a decline in the nutritional value of the oil. Antioxidants are substances present in natural and synthetic forms and prevent several oxidation processes by various antioxidant mechanisms, such as free radical scavenging, metal chelating, and singlet oxygen quenching. A comprehensive study was conducted, and a tailor-made strategy was developed for one-factor at-a-time analysis that utilizes thirteen natural and synthetic antioxidants from various classes with different mechanisms with 0.9mM at 25°C under darkness in the presence of air for 50 days to maintain the oxidative stability of the oil. catechin, sinapic acid, caffeic acid, resveratrol, quercetin, and vanillic acid were found to be highly effective factors in preventing oxidation. A full factorial design (24) was utilized to choose a combination of natural antioxidants (catechin, resveratrol, sinapic acid, and vanillic acid) and synthetic antioxidants (TBHQ, BHA, and BHT) which exhibit interactive effects and response surface modelling (RSM) was used to identify the optimal concentration of the selected antioxidant mixture, which exhibits the synergistic effect. Natural antioxidants, catechin and resveratrol at 0.5mM and 0.625mM, respectively and synthetic antioxidants, TBHQ and BHT at 0.18mM and 0.18mM, respectively exhibited a strong synergistic effect. The kinetic and thermodynamic study of synthetic antioxidant (TBHQ and BHT) combination at several temperatures (25, 35, and 45°C) shows that the decomposition follows a zero-order reaction irrespective of the presence/absence of antioxidants, their concentrations, and storage temperatures. The thermodynamic analysis revealed that the formation of peroxides in the sardine oil is an endothermic, endergonic, and non-spontaneous reaction at ambient temperature.