Edward John Birch

Anaerobic batch digestion of sheep tallow

Abstract Anaerobic batch digestion reactors were operated at mesophilic (35°C) and thermophilic (50°C) temperatures with sheep tallow at levels up to 59% of the volatile solids. Tallow was rapidly fermented to long-chain fatty acids (LCFA) and volatile fatty acids (VFA) at 35°C, but was refractory at 50°C. Oleic acid was fermented to palmitic, stearic and acetic acid. Methanogenesis was delayed by characteristic adaptation periods before LCFA and VFA were completely degraded. This demonstrated that wastes with high lipid contents are amenable to stabilization by mesophilic batch digestion.

Effect of ultrasonic treatment on the polyphenol content and antioxidant capacity of extract from defatted hemp, flax and canola seed cakes.

The effectiveness of ultrasonic extraction of phenolics and flavonoids from defatted hemp, flax and canola seed cakes was compared to the conventional extraction method. Ultrasonic treatment at room temperature showed increased polyphenol extraction yield and antioxidant capacity by two-fold over the conventional extraction method. Different combinations of ultrasonic treatment parameters consisting of solvent volume (25, 50, 75 and 100 mL), extraction time (20, 30 and 40 min) and temperature (40, 50, 60 and 70 °C) were selected for polyphenol extractions from the seed cakes. The chosen parameters had a significant effect (p<0.05) on the polyphenol extraction yield and subsequent antioxidant capacity from the seed cakes. Application of heat during ultrasonic extraction yielded higher polyphenol content in extracts compared to the non-heated extraction. From an orthogonal design test, the best combination of parameters was 50 mL of solvent volume, 20 min of extraction time and 70 °C of ultrasonic temperature.

Radical scavenging activity of lipophilized products from lipase-catalyzed transesterification of triolein with cinnamic and ferulic acids.

Lipase-catalyzed transesterification of triolein with cinnamic and ferulic acids using an immobilized lipase from Candida antarctica (E.C. 3.1.1.3) was conducted to evaluate the antioxidant activity of the lipophilized products as model systems for enhanced protection of unsaturated oil. The lipophilized products were identified using ESI-MS. Free radical scavenging activity was determined using the DPPH radical method. The polarity of the solvents proved important in determining the radical scavenging activity of the substrates. Ferulic acid showed much higher radical scavenging activity than cinnamic acid, which has limited activity. The esterification of cinnamic acid and ferulic acid with triolein resulted in significant increase and decrease in the radical scavenging activity, respectively. These opposite effects were due to the effect of addition of electron-donating alkyl groups on the predominant mechanism of reaction (hydrogen atom transfer or electron transfer) of a species with DPPH. The effect of esterification of cinnamic acid was confirmed using ethyl cinnamate which greatly enhances the radical scavenging activity. Although, compared to the lipophilized cinnamic acid product, the activity was lower. The radical scavenging activity of the main component isolated from lipophilized cinnamic acid product using solid phase extraction, monocinnamoyl dioleoyl glycerol, was as good as the unseparated mixture of lipophilized product. Based on the ratio of a substrate to DPPH concentration, lipophilized ferulic acid was a much more efficient radical scavenger than lipophilized cinnamic acid.

Addition of Milk to Tea Infusions: Helpful or Harmful?; Evidence from In vitro and In vivo Studies on Antioxidant Properties

ABSTRACT Tea consumption is practised as a tradition, and has shown potential to improve human health. Maximal uptake of tea antioxidants and milk proteins without a negative impact on tea flavor is highly desired by consumers. There is a conflicting evidence of the effect of milk addition to tea on antioxidant activity. Differences in the type of tea, the composition, type and amount of milk, preparation method of tea–milk infusions, the assays used to measure antioxidant activity, and sampling size likely account for different findings. Interactions between tea polyphenols and milk proteins, especially between catechins and caseins, could account for a decrease in antioxidant activity, although other mechanisms are also possible, given the similar effects between soy and bovine milk. The role of milk fat globules and the milk fat globule membrane surface is also important when considering interactions and loss of polyphenolic antioxidant activity, which has not been addressed in the literature.

Molecular interactions between green tea catechins and cheese fat studied by solid-state nuclear magnetic resonance spectroscopy

Molecular integrations between green tea catechins and milk fat globules in a cheese matrix were investigated using solid-state magic angle spinning nuclear magnetic resonance spectroscopy. Full-fat cheeses were manufactured containing free catechin or free green tea extract (GTE), and liposomal encapsulated catechin or liposomal encapsulated GTE. Molecular mobility of the carbon species in the cheeses was measured by a wide-line separation technique. The (1)H evolution frequency profile of the (13)C peak at 16ppm obtained for the control cheese and cheeses containing encapsulated polyphenols (catechin or GTE) were similar, however, the spectrum was narrower for cheeses containing free polyphenols. Differences in spectral width indicates changes in the molecular mobility of --CH3- or -C-C-PO4- species through hydrophobic and/or cation-π associations between green tea catechins and cheese fat components. However, the similar spectral profile suggests that encapsulation protects cheese fat from interaction with catechins.

Radical Scavenging Activity of Lipophilized Products from Transesterification of Flaxseed Oil with Cinnamic Acid or Ferulic Acid

Lipase-catalyzed transesterification of flaxseed oil with cinnamic acid (CA) or ferulic acid (FA) using an immobilized lipase from Candida antarctica (E.C. 3.1.1.3) was conducted to evaluate whether the lipophilized products provided enhanced antioxidant activity in the oil. Lipase-catalyzed transesterification of flaxseed oil with CA or FA produced a variety of lipophilized products (identified using ESI-MS-MS) such as monocinnamoyl/feruloyl-diacylglycerol, dicinnamoyl-monoacylglycerol and monocinnamoyl-monoacylglycerol. The free radical scavenging activity of the lipophilized products of lipase-catalyzed transesterification of flaxseed oil with CA or FA toward 2,2-diphenyl-1-picrylhydrazyl radical (DPPH·) were both examined in ethanol and ethyl acetate. The polarity of the solvents proved important in determining the radical scavenging activity of the substrates. Unesterified FA showed the highest free radical scavenging activity among all substrates tested while CA had negligible activity. The esterification of CA or FA with flaxseed oil resulted in significant increase and decrease in the radical scavenging activity compared with the native phenolic acid, respectively. Based on the ratio of a substrate to DPPH· concentration, lipophilized FA was a much more efficient free radical scavenger compared to lipophilized CA and was able to provide enhanced antioxidant activity in the flaxseed oil. Lipophilized cinnamic acid did not provide enhanced radical scavenging activity in the flaxseed oil as the presence of natural hydrophilic antioxidants in the oil had much greater radical scavenging activity.

Analysis of intact triacylglycerols in cold pressed canola, flax and hemp seed oils by HPLC and ESI-MS

Cold-pressed canola, hemp and flax seed oils were separated into their respective intact triglycerides via high pressure liquid chromatography (HPLC) and their fatty acids analysed. Molecular weights of the triglycerides were determined by electrospray ionization-mass spectroscopy (ESI-MS). Seven triglycerides were collected for flax seed, and trilinolenoyl-glycerol was the most abundant at 25.9%. Seven triglycerides were separated and collected for canola seed oil with dioleoyl-linolenoyl-glycerol as the most abundant (32.5%). Eight triglycerides were separated and collected from hemp seed oil with trilinoleoyl-glycerol as the most abundant (21.9%). The fatty acid profiles of the separated triglycerides for the three oils were determined to confirm the assignments. Hempseed was found to have the highest content of palmitic acid in the triglyceride fractions collected (5.6%); flax and canola had 4.1% and 3.1% respectively. The results of fatty acid composition analysis of the cold pressed oils showed oleic acid to be the most abundant fatty acid in canola oil at 57.56 ± 0.13%. Linoleic acid was the most abundant in hemp seed oil at 55.64 ± 1.21%, and linolenic acid in flax seed oil at 58.84 ± 0.91%. Enzymatic hydrolysis using pancreatic lipase treatment was performed to analyse positional distribution of fatty acids in the oils. Thin layer chromatography (TLC) was used for separation of 2-monoglycerides and free fatty acids. For all three oils, unsaturated fatty acids marginally preferred the sn-2 position on the glycerol backbone. Flaxseed had 59.1% of linolenic acid on sn-2 position. At 58.6%, oleic acid was the most abundant fatty acid at the sn-2 position in canola oil, and for linoleic acid in hemp seed oil, 58.2%. Higher ratios of saturated fatty acids to unsaturated fatty acids were located on sn-1, 3 positions.

Effects of (+)-Catechin on the Composition, Phenolic Content and Antioxidant Activity of Full-Fat Cheese during Ripening and Recovery of (+)-Catechin after Simulated In Vitro Digestion

(+)-Catechin, the representative catechin in green tea, was incorporated into a full-fat cheese (at 125–500 ppm) followed by ripening for 90 days at 8 °C and digesting for six hours. Determination of pH, proximate composition, total phenolic content (TPC) and antioxidant activity (AA) after manufacture and ripening demonstrated that the addition of (+)-catechin significantly (p ≤ 0.05) decreased the pH of both whey and curd during cheese manufacturing and ripening with no significant (p > 0.05) effect on the moisture, protein and fat contents. (+)-Catechin increased TPC, as well as AA, though the increase was not proportional with increasing the concentration of added (+)-catechin. About 57%–69% of (+)-catechin was retained in the cheese curd, whereas about 19%–39% (depending on the concentration) was recovered from the cheese digesta. Transmission electron micrographs showed that the ripened control cheese had a homogeneous pattern of milk fat globules with regular spacing entrapped in a homogenous structure of casein proteins, whereas the addition of (+)-catechin disrupted this homogenous structure. The apparent interaction between (+)-catechin and cheese fat globules was confirmed by Fourier transform infrared spectroscopy. These associations should be taken into account when incorporating antioxidants, such as (+)-catechin, to create functional dairy products, such as cheese.