Enhanced antioxidant capacity of lipoic acid in different food systems through lipase-mediated esterification with phytosterols

BACKGROUND

α-Lipoic acid has excellent antioxidant activity, but its poor lipid solubility greatly limits its practical application. This study was undertaken (i) to develop a novel and efficient enzymatic synthesis of lipophilic lipoic acid esters using Candida sp. 99-125 lipase as a catalyst; and (ii) to systematically evaluate their antioxidant potential against bulk oil, oil-in-water emulsion (O/W) and cooked ground meat.

RESULTS

Lipophilic lipoic acid esters were successfully and efficiently synthesized using phytosterols as acyl receptor in the presence of Candida sp. 99-125 lipase. The product was identified as phytosterol lipoate by mass spectrometry, Fourier transform infrared spectroscopy and nuclear magnetic resonance. The maximum conversion of phytosterol lipoate surpassed 90% within 12 h and its final yield exceeded 81%. Interestingly, the oil solubility of lipoic acid was increased at least 25-fold and other physicochemical properties were significantly improved. Most importantly, phytosterol lipoate exhibited higher antioxidant activity than lipoic acid in bulk oil, O/W emulsions and cooked ground meat.

CONCLUSION

The antioxidant capacity of lipoic acid can be significantly enhanced by esterification with phytosterols. Therefore, phytosterol lipoate could be further developed as a new antioxidant for use in oil- and fat-based foods. © 2022 Society of Chemical Industry.

Statistical Optimization of Biodiesel Production from Salmon Oil via Enzymatic Transesterification: Investigation of the Effects of Various Operational Parameters

The enzymatic transesterification of Atlantic salmon (Salmo salar) oil was carried out using Novozym 435 (immobilized lipase from Candida antartica) to produce biodiesel. A response surface modelling design was performed to investigate the relationship between biodiesel yield and several critical factors, including enzyme concentration (5, 10, or 15%), temperature (40, 45, or 50 °C), oil/alcohol molar ratio (1:3, 1:4, or 1:5) and time (8, 16, or 24 h). The results indicated that the effects of all the factors were statistically significant at p-values of 0.000 for biodiesel production. The optimum parameters for biodiesel production were determined as 10% enzyme concentration, 45 °C, 16 h, and 1:4 oil/alcohol molar ratio, leading to a biodiesel yield of 87.23%. The step-wise addition of methanol during the enzymatic transesterification further increased the biodiesel yield to 94.5%. This is the first study that focused on Atlantic salmon oil-derived biodiesel production, which creates a paradigm for valorization of Atlantic salmon by-products that would also reduce the consumption and demand of plant oils derived from crops and vegetables.

Exploring the Impact of Lipid-Rich Food Industry Waste Carbon Sources on the Growth of Candida cylindracea DSM 2031

The aim of this study was to evaluate the possibility of using several lipid-rich food industry wastes in the culture medium on the growth of Candida cylindracea DSM 2031 yeast strain. Four lipid wastes from the food industry: waste fish oil, rancid ghee, waste pork lard, and waste duck processing oil were investigated. It has been shown in the laboratory scale that the above-mentioned wastes can be used to obtain biomass and produce lipolytic enzymes by the tested strain and the C. cylindracea extracellular lipase is not constitutive. High yields of biomass (12.84, 12.75, and 12.24 g/dm3) were obtained in media containing waste duck processing oil, olive oil, and waste pork lard, respectively. The highest lipolytic activity was obtained in the media containing waste fish oil and rancid ghee (0.050 and 0.047 U/cm3). During 192-h flask cultures the highest extracellular lipase activity and biomass yield were observed in the late logarithmic phase. The study showed that there is a potential for waste management to produce lipolytic enzymes or to produce yeast biomass. The use of waste substrates may contribute to lowering the costs of commercial production, and such a solution is part of the sustainable development strategy.