John Birch

Antioxidative Polyphenols from Defatted Oilseed Cakes: Effect of Solvents

Defatted hemp, flax and canola seed cakes were extracted with different solvent systems namely methanol, ethanol, acetone, methanol 80%, acetone 80% and mixed solvent of methanol:acetone:water (MAW, 7:7:6, v/v/v). Each extract was analyzed for antioxidant capacity using ferric reducing/antioxidant power (FRAP) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. MAW exhibited the highest extraction of phenolic and flavonoid contents in the seed cakes, followed by acetone 80% and methanol 80%. The antioxidant capacity was proportional to the polyphenols recovery in the extracts. Canola seed cakes possessed the highest recovery of polyphenols and antioxidant capacity, followed by hemp and flax seed cakes. MAW extract of canola contained total phenolic content, 2104.67 ± 2.52 mg GAE/100 g fresh weight; total flavonoids, 37.79 ± 0.04 mg LUE/100 g fresh weight; percentage inhibition of DPPH•, 33.03 ± 0.38%; FRAP assay, 8.78 ± 0.07 μmol Fe (II)/g fresh weight. Identification of individual polyphenol compounds were performed HPLC. MAW extract of canola had the highest (P < 0.05) concentration of all individual polyphenols except gallic acid and catechin. Highest concentration of quercetin and luteolin in MAW extract of hemp was obtained among all solvent systems.

Antioxidant and ACE-inhibitory activities of hemp (Cannabis sativa L.) protein hydrolysates produced by the proteases AFP, HT, Pro-G, actinidin and zingibain

Hemp protein isolates (HPIs) were hydrolysed by proteases (AFP, HT, ProG, actinidin and zingibain). The enzymatic hydrolysis of HPIs was evaluated through the degree of hydrolysis and SDS-PAGE profiles. The bioactive properties of the resultant hydrolysates (HPHs) were accessed through ORAC, DPPḢ scavenging and ACE-inhibitory activities. The physical properties of the resultant HPHs were evaluated for their particle sizes, zeta potential and surface hydrophobicity. HT had the highest rate of caseinolytic activity at the lowest concentration (0.1 mg mL(-1)) compared to other proteases that required concentration of 100 mg mL(-1) to achieve their maximum rate of caseinolytic activity. This led to the highest degree of hydrolysis of HPIs by HT in the SDS-PAGE profiles. Among all proteases and substrates, HT resulted in the highest bioactivities (ORAC, DPPḢ scavenging and ACE-inhibitory activities) generated from alkali extracted HPI in the shortest time (2 h) compared to the other protease preparations.

Optimization of polyphenol extraction and antioxidant activities of extracts from defatted flax seed cake (Linum usitatissimum L.) using microwave-assisted and pulsed electric field (PEF) technologies with response surface methodology

Use of microwave and pulsed electric field (PEF) technologies for optimization of polyphenol extraction from defatted flax seed cake was attempted using a Box-Behnken response surface design. Polyphenols were extracted after microwave or PEF treatments using ultrasound under fixed variables of 200 W of ultrasonic power, a 70°C water bath, and 20 min of extraction time. Measured responses were total phenolic and total flavonoid contents, and 2,2,-diphenyl-1-picrylhydrazyl radical (DPPH·) scavenging activity and ferric reducing/antioxidant power activities. Maximum yields of all responses were achieved under optimum conditions for microwave processing=5 min, a liquid to solid ratio=6, and at 644 W, and for PEF-assisted extraction for 30 V at 30 Hz with a 10% ethanol concentration, and a treatment time=10 s. Under optimized microwave or PEF processing conditions, yields of polyphenols from defatted seed cake were maximized.

Potential of Extracted Locusta Migratoria Protein Fractions as Value-Added Ingredients

Although locusts can be sustainably produced and are nutrient rich, the thought of eating them can be hard to swallow for many consumers. This paper aims to investigate the nutritional composition of Locusta migratoria, including the properties of extracted locust protein, contributing to limited literature and product development opportunities for industry. Locusts sourced from Dunedin, New Zealand, contained a high amount of protein (50.79% dry weight) and fat (34.93%), which contained high amounts of omega-3 (15.64%), creating a desirably low omega-3/omega-6 ratio of 0.57. Three protein fractions including; insoluble locust fraction, soluble locust fraction, and a supernatant fraction were recovered following alkali isoelectric precipitation methodology. Initially, proteins were solubilised at pH 10 then precipitated out at the isoelectric point (pH 4). All fractions had significantly higher protein contents compared with the whole locust. The insoluble protein fraction represented 37.76% of the dry weight of protein recovered and was much lighter in colour and greener compared to other fractions. It also had the highest water and oil holding capacity of 5.17 mL/g and 7.31 mL/g, possibly due to larger particle size. The high supernatant yield (56.60%) and low soluble protein yield (9.83%) was unexpected and could be a result of experimental pH conditions chosen.

Lipases for Biofuel Production

Challenges associated with global resource depletion, anthropogenic greenhouse gas generation and global warming, due to extensive fossil fuel utilisation have catalysed the exploration of pathways for alternative biofuel production to reduce unwanted environmental outcomes. Crucially however, existing biofuel production processes have been characterised by unfavourable environmental outcomes largely due to secondary toxicity effects arising from the use of mineral acids (or mineral alkalis) to catalyse biofuel production processes. To therefore improve the environmental performances of biofuel production processes, several researchers have investigated the feasibility of enhanced and sustainable environmentally-benign lipase catalysed biofuel production processes.

Effect of solvents on polyphenol recovery and antioxidant activity of isolates of Asparagus Officinalis roots from Chinese and New Zealand cultivars

Nine solvents of varying polarity (water, methanol, ethanol, isopropyl alcohol, acetone, n-butyl alcohol, ethyl acetate, chloroform and petroleum ether) were used to determine the optimal extraction solvent that gives the highest yield of bioactive compounds from six Asparagus Officinalis L root (AR) cultivars from China and New Zealand. The contents of total phenolics (TPC), total flavonoids (TFC), total saponins (TSC) and caffeic acid (CA) were determined. Antioxidant assessments included ferric reducing/antioxidant power (FRAP), 2, 20-azinobis-(3diphenyl-ethylbenzothiazoline-6-sulphonic acid) radical cation (ABTS) and b-carotene bleaching activity assays. The results indicated that yellow AR from China had the highest content of TPC, TFC, TSC and CA compared to other AR cultivars. The most effective solvents for bioactive compound recoveries and antioxidant activities from A. officinalis L root extraction were ethanol and methanol. The content of CA in ethanol extracts of yellow AR achieved 92.0 mg g 1 DE.

Lipase-Catalyzed Production of Biodiesel from Tallow

The use of enzymes (lipases) to convert triglycerides to acylesters (biodiesel) holds potential as an alternative to the conventional base catalyzed processes. Advantages include the ability to utilize impure feedstocks, less downstream processing, and potentially overcoming the requirement to dedicate expensive agricultural land for raw oil production. Lipid sources such as oleaginous microorganisms along with processing wastes may provide renewable substrates requiring minimal pre-processing. Transesterification of vegetable oils and restaurant grease has been studied using immobilized enzymes as catalysts with an optimal temperature of around 35°C. This study investigates ester formation from unrefined tallow at 50°C employing similar enzymes used for vegetable oils. Novozyme 435 (a commercially available immobilized enzyme) proved best at a loading of 2 % w/w based on tallow reaching 98 % conversion after 96 h using methanol as the chosen alcohol, with immobilized lipase from Pseudomonas cepacia (PS-30) (69 % conversion) proving superior to free PS-30 (11 % conversion), and the other lipases barely registering any activity. Immobilized PS-30 was chosen to investigate the effect of lipase level, alcohol reactant, water content of the tallow, grade of tallow, and influence of solvent or a solvent-free system. Results showed that water content of up to 0.6 % and the tallow grade had no effect on ester formation, while enzyme loadings of at least 4 % were needed to achieve a good conversion that plateaued at around 6–8 % water content. The primary alcohols ethanol, propanol, and butanol reacted equally efficiently with immobilized PS-30, reaching 96–99 % conversion, while methanol performed less well along with 2-propanol and 2-butanol where conversion was only in the range of 10–40 %. Transesterification reactions worked best in a non-polar environment with hexane as solvent (95 % conversion), with a higher polarity solvent, acetonitrile, also proving an efficient medium (80 % conversion), while solvents intermediate to these had little comparative activity, suggesting that solubility of reactants and products is a key driver in the conversion. Interestingly, petro-diesel proved to be a better solvent than using either a solvent-free system or a diethylether environment.