A Novel Model for Evaluating the Natural Antioxidant Carnosic Acid to Improve the Stability of Rapeseed Oil in the Thermal Degradation.

The quality and stability of oil during thermal processing reflect the reactions in vegetable oil. The deterioration of the oil is close to the viscosity, fatty acid composition (FA), total polar compounds (TPC), etc. Carnosic acid (CA) is the main antioxidant component of rosemary extract; it is a natural and clean-label antioxidant that is allowed to be added to prolong oil processing and storage. To achieve a clear correlation of this situation, a novel stability evaluation model was used to predict the thermal degradation of rapeseed oil (RSO) with CA. The RSO with CA (200 mg/kg, 400 mg/kg, and 700 mg/kg), the tert-Butylhydroquinone (TBHQ, 200 mg/kg), and the fresh RSO (without additives) during thermal processing (180 ± 5 °C) were studied. The temperature dependency of viscosity fits well with the Lioumbas model (R2 ≥ 0.999). The parameter b value in the Lioumbas model showed a decrease linearly with the processing time (tP, R2 ≥ 0.965). The multiple linear regression analysis showed that the accuracy of the model in predicting viscosity was less than ±2 mPa·s-1, and the deviation% was less than ±10% in all the samples. After 32 h of thermal degradation, the addition of 700 mg/kg CA showed the lowest degradation rate (13.84%) of polyunsaturated fatty acids (PUFAs), and the TPC content was 26.00 ± 0.50%. The TPC showed a positive relationship with viscosity (r = 0.99, p < 0.01), tP (r = 0.97, p < 0.01), and effective carbon numbers (ECN, r = 0.84, p < 0.05). In conclusion, this study can make a potential prediction for the stability of RSO.

Antioxidant Efficacy of Rosemary Extract in Improving the Oxidative Stability of Rapeseed Oil during Storage.

Rapeseed oil is an important source of edible oil in the human diet and is also highly susceptible to oxidative deterioration. It has been demonstrated that rosemary extract (RE) can increase the oxidative stability of oils. In this work, the antioxidant capacity of rapeseed oil after the addition of RE during storage and the optimum addition of RE in rapeseed oil were investigated. Oxidative stability evaluation results demonstrate that the shelf life of rapeseed oil with the incorporation of 100 mg/kg of RE was equivalent to that with the addition of 50 mg/kg of tert-butyl hydroxyquinone (TBHQ). Storage test analysis results show that RE remarkably delayed the oxidation of rapeseed oil when the storage container was unsealed. The optimum amount of RE as an addition was 50-200 mg/kg under room temperature storage, while it was 150 mg/kg under Schaal oven storage. The antioxidant capacity of rapeseed oil with 50 mg/kg of RE added was remarkably higher than that with 50 mg/kg of TBHQ added after 20 d of storage, according to the Schaal oven test. Additionally, the addition of RE delayed the degradation of endogenous α-tocopherol in rapeseed oil. This study comprehensively evaluated the antioxidant properties of rapeseed oil when RE was added and it provides a new strategy for establishing healthy, nutritious, and safe oil preservation measures.

Effect of Extraction Methods on the Physicochemical Properties, Chemical Composition, and Antioxidant Activities of Samara Oil.

Samara oil (Elaeagnus mollis Diels kernel oil) exhibits diverse healthy functions; however, the effect of extraction on its quality is still unclear. The present study was undertaken to evaluate the effect of extraction methods (solvent extraction: ethyl acetate, acetone, n-hexane, and petroleum ether; mechanical extraction: hot-pressing and cold-pressing) on the color, acid value, peroxide value, fatty acid composition, bioactive compounds, antioxidant activities, and oxidative stability index of samara oil obtained from Elaeagnus mollis Diels kernels. The results indicated that extraction methods affected the physicochemical properties, chemical composition, and antioxidant activities of samara oil except for fatty acid composition and γ-tocopherol. The highest values of bioactive compounds including polyphenols (140.27 mg gallic acid equivalent (GAE)/kg) and carotenoids (42.95 mg/kg) were found in samara oil extracted with acetone. The values of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) assays, as well as oxidative stability index (OSI), were the highest in this oil. Correlation analysis results demonstrated that DPPH, ABTS, and OSI of samara oil were positively correlated with polyphenols and carotenoids. After evaluation, acetone could be used to extract samara oil. The study provides new information on the samara oil process.

Current Technologies and Uses for Fruit and Vegetable Wastes in a Sustainable System: A Review.

The fruit and vegetable industry produces millions of tons of residues, which can cause large economic losses. Fruit and vegetable wastes and by-products contain a large number of bioactive substances with functional ingredients that have antioxidant, antibacterial, and other properties. Current technologies can utilize fruit and vegetable waste and by-products as ingredients, food bioactive compounds, and biofuels. Traditional and commercial utilization in the food industry includes such technologies as microwave-assisted extraction (MAE), supercritical fluid extraction (SFE), ultrasonic-assisted extraction (UAE), and high hydrostatic pressure technique (HHP). Biorefinery methods for converting fruit and vegetable wastes into biofuels, such as anaerobic digestion (AD), fermentation, incineration, pyrolysis and gasification, and hydrothermal carbonization, are described. This study provides strategies for the processing of fruit and vegetable wastes using eco-friendly technologies and lays a foundation for the utilization of fruit and vegetable loss/waste and by-products in a sustainable system.

Evaluation of the Candida sp. 99-125 Lipase Positional Selectivity for 1,3-Diolein Synthesis.

In this study, comparative experiments were carried out to investigate the positional selectivity of Candida sp. 99-125 lipase in preparing 1,3-diolein by using medium engineering strategy. The results indicated that the diolein yield was markedly enhanced from 56.5% to 86.7% with increasing log⁡P values of the solvents, while the selectivity of the examined lipase for the sn-1 over the sn-2 hydroxyl of glycerol was decreased, thus leading to a reduced 1,3-diolein to 1,2-diolein ratio. To evaluate the possibility of industrial enzymatic production of 1,3-diolein, larger-scale experiments were assessed. After being used repeatedly for eight batches, the diolein content reached 95.1%, while the 1,3-diolein to 1,2-diolein ratio was 7:1 following purification. Results of the kg level experiments significantly demonstrated the practicability of the enzymatic process and the efficiency of the purification strategy for the product.

Efficient Regioselective Synthesis of the Crotonyl Polydatin Prodrug by Thermomyces lanuginosus Lipase: a Kinetics Study in Eco-friendly 2-Methyltetrahydrofuran.

Bio-based solvents have recently been discussed as sustainable green and promising alternatives to conventional organic media for enzymatic processes. In this paper, highly regioselective synthesis of the 6″-O-crotonyl-polydatin catalyzed by Thermomyces lanuginosus lipase (TLL) in biomass-derived 2-methyltetrahydrofuran (2-MeTHF) was successfully performed for the first time. The results indicated that TLL lipase displayed significantly improved catalytic performance in 2-MeTHF than in other traditional solvents. Under the optimal conditions, the initial reaction rate, 6″-regioselectivity, and maximum substrate conversion were as high as 12.38 mM h(-1), 100 %, and 100 %, respectively. Moreover, further investigations on the operational stability, kinetic parameters like V max, K m, V max/K m, and E a revealed that 2-MeTHF exhibited excellent biocompatibility and rendered the greener process of the enzymatic acylation.

The halo-substituent effect on Pseudomonas cepacia lipase-mediated regioselective acylation of nucleosides: A comparative investigation.

In this work, comparative experiments were explored to investigate the substrate specificity of Pseudomonas cepacia lipase in regioselective acylation of nucleosides carrying various substituents (such as the H, F, Cl, Br, I) at 2'- and 5-positions. Experimental data indicated that the catalytic performance of the enzyme depended very much on the halo-substituents in nucleosides. The increased bulk of 2'-substituents in ribose moiety of the nucleoside might contribute to the improved 3'-regioselectivity (90-98%, nucleosides a-d) in enzymatic decanoylation, while the enhancement of regioselectivity (93-99%) in 3'-O-acylated nucleosides e-h could be attributable to the increasing hydrophobicity of the halogen atoms at 5-positions. With regard to the chain-length selectivity, P. cepacia lipase displayed the highest 3'-regioselectivity toward the longer chain (C14) as compared to shorter (C6 and C10) ones. The position, orientation and property of the substituent, specific structure of the lipase's active site, and acyl structure could account for the diverse results.

Introducing biobased ionic liquids as the nonaqueous media for enzymatic synthesis of phosphatidylserine.

Biobased ionic liquids with cholinium as the cation and amino acids as the anions, which could be prepared from renewable biomaterials by simple neutralization reactions, have recently been described as promising and green solvents. Herein, they were successfully used as the reaction media for enzyme-mediated transphosphatidylation of phosphatidylcholine with l-serine for phosphatidylserine synthesis for the first time. Our results indicated that the highest phosphatidylserine yield of 86.5% was achieved. Moreover, 75% original activity of the enzyme was maintained after being used for 10 batches. The present work could be considered an alternative enzymatic strategy for preparing phosphatidylserine. Additionally, the excellent results make the biobased ionic liquids more promising candidates for use as environmentally friendly solvents in biocatalysis fields.

Improved synthesis of phosphatidylserine using bio-based solvents, limonene and p-cymene.

PURPOSE OF WORK: The bio-based solvents limonene and p-cymene obtained from citrus waste were innovatively employed as the reaction media for enzymatic synthesis of phosphatidylserine. (R)-(+)-Limonene, which is available in large quantities from citrus waste, and its close derivative p-cymene, are promising green solvents. Herein, they were successfully employed as reaction media for enzyme-mediated transphosphatidylation of phosphatidylcholine with L-serine for phosphatidylserine synthesis for the first time. A 95 % yield of phosphatidylserine was achieved after 12 h and the side-reactions (which are the undesirable hydrolysis of phosphatidylcholine and phosphatidylserine) did not happen. This work presents an alternative strategy for preparing phosphatidylserine that possesses obvious advantages over the traditional processes in terms of high efficiency combined with environmental friendliness.

A novel phospholipase D constitutively secreted by Ochrobactrum sp. ASAG-PL1 capable of enzymatic synthesis of phosphatidylserine.

Phospholipase D (PLD) plays a crucial role in the enzyme-mediated preparation of phosphatidylserine (PS). A new PLD constitutively secreted by Ochrobactrum sp. ASAG-PL1 is now reported for the first time. After purification, the MW of the enzyme was ~37 kDa by SDS-PAGE. Its activity was highest at 40 °C and pH 7.0 and more than 90 % of the initial activity was maintained after 30 days at 4 °C and pH 7.0. This enzyme may then be useful as a potential biocatalyst for PS production.

Efficient synthesis of phosphatidylserine in 2-methyltetrahydrofuran.

2-Methyltetrahydrofuran has recently been described as a promising and green solvent. Herein, it was successfully used as the reaction medium for enzyme-mediated transphosphatidylation of phosphatidylcholine with L-serine with the aim of phosphatidylserine synthesis for the first time. Our results indicated that as high as 90% yield of phosphatidylserine could be achieved after 12 h combined with no byproduct (phosphatidic acid) forming. The present work accommodated a facilely and efficiently enzymatic strategy for preparing phosphatidylserine, which possessed obvious advantages over the reported processes in terms of high efficiency and environmental friendliness. This work is also a proof-of-concept opening the use of 2-methyltetrahydrofuran in biosynthesis as well.

Rational synthesis of 1,3-diolein by enzymatic esterification.

t-Butanol was an excellent reaction medium for enzyme-mediated esterification of oleic acid with glycerol for 1,3-diolein preparation which has been proved by our group. Herein, to achieve the rational synthesis of 1,3-diolien, response surface methodology was applied to examine the effects of the significant variables and their reciprocal effects on the product synthesis. Under the optimal conditions (62.4°C, 0.75g Novozym 435, substrate molar ratio (oleic acid/glycerol) 2.4 and 4.8g t-butanol), the diolein yield of 87.4% could be achieved, and the value of 1,3-diolien/diolein was as high as 87.8%, which were quite close to the predicted values. Compared with the results of our previous single factor experiment, although the values of diolein yield and 1,3-diolien/diolein could not be improved markedly, the enzyme dosage and the reaction medium were spared by 25% and 20%, respectively, which was a remarkable improvement of the enzymatic process.

The mechanism of solvent effect on the positional selectivity of Candida antarctica lipase B during 1,3-diolein synthesis by esterification.

We investigated the influence of solvent on the positional selectivity of Novozym 435 which was the immobilized Candida antarctica lipase B (CALB) during the esterification of oleic acid with glycerol for 1,3-diolein preparation previously. Herein, molecular modeling was used to elucidate the underlying mechanism of the solvent effect on the positional selectivity of the enzyme. The results showed that the binding energy of sn-1 hydroxyl of glycerol molecular with CALB became higher, and the binding energy of sn-2 hydroxyl of glycerol molecular with CALB became lower along with the increase of the solvent log P. It was demonstrated that, increasing log P of the solvent, the enzyme selectivity to sn-1 hydroxyl of glycerol molecular grew weaker, and the selectivity to sn-2 hydroxyl of glycerol molecular grew stronger.

The solvent influence on the positional selectivity of Novozym 435 during 1,3-diolein synthesis by esterification.

The influence of solvents with a wide range of log P (from -0.23 to 4.5) on the positional selectivity of the immobilized lipase Novozym 435 during the esterification of oleic acid with glycerol for 1,3-diolein preparation was investigated. Analysis was performed on the basis of a simplified kinetic model of 1,3-diolein synthesis. The results showed that the preferential selectivity of Novozym 435 to 1-position over 2-position of the glycerol molecular became weaker and weaker with the increasing log P of the solvent. But after one 1-position was acylated, the preferential selectivity to the other 1-position over 2-position would be enhanced strongly for each solvent. The study also revealed that relatively hydrophilic solvent such as t-butanol was an ideal solvent for Novozym 435 catalyzed 1,3-diolein synthesis through esterification of oleic acid with glycerol.

Efficient production of biodiesel from high free fatty acid-containing waste oils using various carbohydrate-derived solid acid catalysts.

In the present study, such carbohydrate-derived catalysts have been prepared from various carbohydrates such as d-glucose, sucrose, cellulose and starch. The catalytic and textural properties of the prepared catalysts have been investigated in detail and it was found that the starch-derived catalyst had the best catalytic performance. The carbohydrate-derived catalysts exhibited substantially higher catalytic activities for both esterification and transesterification compared to the two typical solid acid catalysts (sulphated zirconia and Niobic acid), and gave markedly enhanced yield of methyl esters in converting waste cooking oils containing 27.8wt% high free fatty acids (FFAs) to biodiesel. In addition, under the optimized reaction conditions, the starch-derived catalyst retained a remarkably high proportion (about 93%) of its original catalytic activity even after 50 cycles of successive re-use and thus displayed very excellent operational stability. Our results clearly indicate that the carbohydrate-derived catalysts, especially the starch-derived catalyst, are highly effective, recyclable, eco-friendly and promising solid acid catalysts that are highly suited to the production of biodiesel from waste oils containing high FFAs.