Daoming Li

A stearic acid-rich diet improves thrombogenic and atherogenic risk factor profiles in healthy males

Objective: To determine whether healthy males who consumed increased amounts of dietary stearic acid compared with increased dietary palmitic acid exhibited any changes in their platelet aggregability, platelet fatty acid profiles, platelet morphology, or haemostatic factors.Design: A randomized cross-over dietary intervention.Subjects and interventions: Thirteen free-living healthy males consumed two experimental diets for 4 weeks with a 7 week washout between the two dietary periods. The diets consisted of ∼30% of energy as fat (66% of which was the treatment fat) providing ∼6.6% of energy as stearic acid (diet S) or ∼7.8% of energy as palmitic acid (diet P). On days 0 and 28 of each dietary period, blood samples were collected and anthropometric and physiological measurements were recorded.Results: Stearic acid was increased significantly in platelet phospholipids on diet S (by 22%), while on diet P palmitic acid levels in platelet phospholipids also increased significantly (8%). Mean platelet volume, coagulation factor FVII activity and plasma lipid concentrations were significantly decreased on diet S, while platelet aggregation was significantly increased on diet P.Conclusion: Results from this study indicate that stearic acid (19 g/day) in the diet has beneficial effects on thrombogenic and atherogenic risk factors in males. The food industry might wish to consider the enrichment of foods with stearic acid in place of palmitic acid and trans fatty acids.Sponsorship: Grant from Meat Research Corporation, Australia and margarines donated by Meadow Lea Foods Ltd, Australia.European Journal of Clinical Nutrition (2001) 55, 88–96

The influence of fish, meat and polyunsaturated fat intakes on platelet phospholipid polyunsaturated fatty acids in male Melbourne Chinese and Caucasian

Objective: The aims of this study were to investigate (1) platelet phospholipid (PL) polyunsaturated fatty acid (PUFA) composition in subjects who were the Melbourne Chinese migrants, compared with those who were the Melbourne Caucasians and (2) the relationship between platelet PL PUFA and intake of fish, meat and PUFA.Design: Cross-sectional comparison of the Melbourne Chinese and Caucasians.Setting: Free-living male subjects.Subjects: Ninety-seven Melbourne Chinese migrants and 78 Melbourne Caucasians who were recruited in Melbourne.Outcome measures: Dietary intake was assessed using a semi-quantitative food frequency questionnaire. The platelet PUFA was measured by gas–liquid chromatography.Results: The Melbourne Chinese had significantly higher proportions of platelet PL 20:5n‐3 (P=0.006), 22:6n‐3 (P<0.0001), total n‐3 (P=0.027) and 22:5n‐6 (P=0.0002), and a significantly higher intake of fish (P=0.012) and white meat (P=0.0045) compared with the Melbourne Caucasians. In addition, the Melbourne Chinese had significantly lower proportions of 20:3n‐6 (P=0.023), 20:4n‐6 (P<0.002), 22:4n‐6 (P<0.0001), total n‐6 (P=0.037), 22:5n‐3 (P<0.0001) and ratio of n‐6/n‐3 (P=0.011), and a significantly lower intake of red and total meat (P<0.0001) than the Melbourne Caucasians. Fish consumption was significantly positively correlated with platelet PL 20:5n‐3 and 22:6n‐3, and significantly negatively correlated with 22:5n‐3 (P<0.05). Meat consumption was significantly positively correlated with 22:5n‐3 and significantly negatively correlated with 22:5n‐6, 20:5n‐3 and 22:6n‐3 (P<0.05). Dietary PUFA intake was significantly positively correlated with 20:3n‐6, 22:4n‐6 and 22:5n‐3, and significantly negatively correlated with 22:5n‐6, 20:5n‐3 and 22:6n‐3 (P<0.05).Conclusions: Compared with Caucasians, the Melbourne Chinese had a significantly higher level of platelet PL n‐3 PUFA, which might contribute to the low CVD mortality in this population. Platelet PL 20:5n‐3 and 22:6n‐3 were significantly positively correlated with fish intake, and negatively significantly correlated with dietary intake of meat and PUFA, while 22:5n‐3 was significantly positively correlated with dietary meat and PUFA intake, and significantly negatively correlated with fish intake. Dietary intake of PUFA and fish are potential confounding factors for assessing the effects of meat consumption on platelet PL individual PUFA. Dietary intake of PUFA and meat did not influence the incorporation of fish long chain n‐3 PUFA to platelet PL in this study population.Sponsorship: Palm Oil Research Institute of Malaysia, Meat Research Corporation Australia.European Journal of Clinical Nutrition (2001) 55, 1036–1042

One-step synthesis of high-yield biodiesel from waste cooking oils by a novel and highly methanol-tolerant immobilized lipase

This study reported a novel immobilized MAS1 lipase from marine Streptomyces sp. strain W007 for synthesizing high-yield biodiesel from waste cooking oils (WCO) with one-step addition of methanol in a solvent-free system. Immobilized MAS1 lipase was selected for the transesterification reactions with one-step addition of methanol due to its much more higher biodiesel yield (89.50%) when compared with the other three commercial immobilized lipases (<10%). The highest biodiesel yield (95.45%) was acquired with one-step addition of methanol under the optimized conditions. Moreover, it was observed that immobilized MAS1 lipase retained approximately 70% of its initial activity after being used for four batch cycles. Finally, the obtained biodiesel was further characterized using FT-IR, 1H and 13C NMR spectroscopy. These findings indicated that immobilized MAS1 lipase is a promising catalyst for biodiesel production from WCO with one-step addition of methanol under high methanol concentration.

Immobilized MAS1 lipase showed high esterification activity in the production of triacylglycerols with n-3 polyunsaturated fatty acids

Immobilization of lipase MAS1 from marine Streptomyces sp. strain W007 and its application in catalyzing esterification of n-3 polyunsaturated fatty acids (PUFA) with glycerol were investigated. The resin XAD1180 was selected as a suitable support for the immobilization of lipase MAS1, and its absorption ability was 75mg/g (lipase/resin ratio) with initial buffer pH value of 8.0. The thermal stability of immobilized MAS1 was improved significantly compared with that of the free lipase. Immobilized MAS1 had no regiospecificity in the hydrolysis of triolein. The highest esterification degree (99.31%) and TAG content (92.26%) by immobilized MAS1-catalyzed esterification were achieved under the optimized conditions, which were significantly better than those (82.16% and 47.26%, respectively) by Novozym 435. More than 92% n-3 PUFA was incorporated into TAG that had similar fatty acids composition to the substrate (n-3 PUFA). The immobilized MAS1 exhibited 50% of its initial activity after being used for five cycles.

Production of Structured Phosphatidylcholine with High Content of DHA/EPA by Immobilized Phospholipase A1-Catalyzed Transesterification

This paper presents the synthesis of structured phosphatidylcholine (PC) enriched with docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) by transesterification of DHA/EPA-rich ethyl esters with PC using immobilized phospholipsase A1 (PLA1) in solvent-free medium. Firstly, liquid PLA1 was immobilized on resin D380, and it was found that a pH of 5 and a support/PLA1 ratio (w/v) of 1:3 were the best conditions for the adsorption. Secondly, the immobilized PLA1 was used to catalyze transesterification of PC and DHA/EPA-rich ethyl esters. The maximal incorporation of DHA and EPA achieved was 30.7% for 24 h of reaction at 55 °C using a substrate mass ratio (PC/ethyl esters) of 1:6, an immobilized PLA1 loading of 15% and water dosage of 1.25%. Then the reaction mixture was analyzed by 31P nuclear magnetic resonance (NMR). The composition of reaction product included 16.5% PC, 26.3% 2-diacyl-sn-glycero-3-lysophosphatidylcholine (1-LPC), 31.4% 1-diacyl-sn-glycero-3-lysophosphatidylcholine (2-LPC), and 25.8% sn-glycerol-3-phosphatidylcholine (GPC).

The occurrence of trans-18:1 isomers in plasma lipids classes in humans.

Objective: The aim of this study was to examine the distribution of trans fatty acids (TFA) in plasma lipid classes and the relationship with dietary intake of TFA.Design: After a 2 week baseline (habitual) diet, all subjects consumed a moderate fat (MF) diet for 3 weeks with the fat being derived mainly from margarine and the rest from lean beef, and then a very low fat (VLF) diet for 3 weeks with the TFA being derived only from the lean beef. Blood samples were collected 2 days prior to the end and also on the last day of each dietary period.Setting: Deakin Institute of Human Nutrition, Deakin University, Geelong, Australia.Subjects: Ten free-living mildly hypercholesterolaemic subjects aged 22–66 were recruited in Geelong.Outcome measures: TFA intake was calculated from analyses of Australian margarines, butter, lean meat and animal fat. The TFA in plasma lipid fractions were separated by AgNO3 thin-layer chromatography and quantitated by capillary gas–liquid chromatography using internal standards.Results: The phospholipid (PL) fraction contained more than 60% of the trans-18:1 isomers in the plasma lipids in all subjects. On the baseline diet, the predominant positional isomer of trans-18:1 in PL was Δ11, whereas in the other lipid classes it was the Δ9 isomer. The concentration of the Δ9 isomer increased on the MF diet, particularly in the PL fraction, while the concentration of the Δ11 isomer decreased in all fractions. On the VLF diet, the total TFA level decreased by approximately 50%, mainly due to decreases in the TFA isomers in the PL and TG fractions. Changes in plasma total and PL TFA, PL Δ9, Δ10 and Δ11 were strongly correlated with dietary TFA intake (P<0.0001). There were also significant association between dietary TFA intake and PL Δ12 (P=0.003), triacylglycerol Δ9 (P=0.009), Δ11 (P=0.0005), total triacylglycerol (P=0.023) and free fatty acid TFA (P=0.042).Conclusions: The results suggest that the measurement of trans-18:1 in plasma PL and TAG, and plasma total TFA could be used to estimate the intake of TFA.Sponsorship: Meat Research Corporation of Australia.European Journal of Clinical Nutrition (2001) 55, 59–64

A Novel Process for the Synthesis of Highly Pure n-3 Polyunsaturated Fatty Acid (PUFA)-Enriched Triglycerides by Combined Transesterification and Ethanolysis.

In this study, a novel two-step enzymatic reaction was developed for the synthesis of highly pure triacylglycerols (TAGs) with a high content of n-3 polyunsaturated fatty acids (PUFAs). Glyceride mixtures were primarily synthesized by Novozym 435-catalyzed transesterification of glycerol and DHA/EPA-rich ethyl esters (EEs), followed by removal of partial glycerides, for the first time, by immobilized mono- and diacylglycerol lipase SMG1-F278N-catalyzed ethanolysis. TAG yield as high as 98.66% was achieved under the optimized conditions, and highly pure (98.75%) n-3 PUFA-enriched TAGs with 88.44% of n-3 PUFA was obtained after molecular distillation at lower temperature (140 °C). In addition, the EEs produced during ethanolysis had a FA composition similar to that of the original EEs, making them feasible for cyclic utilization. This was the first study reporting removal of partial glycerides by ethanolysis. Through ethanolysis, a higher purity product could be easily obtained at a relatively low temperature compared with the conventional high-temperature molecular distillation.

Simplified Enzymatic Upgrading of High-Acid Rice Bran Oil Using Ethanol as a Novel Acyl Acceptor

One of the major challenges in the upgrading of high-acid rice bran oil (RBO) is to efficiently reduce the amount of free fatty acids. Here we report a novel method for upgrading high-acid RBO using ethanol as a novel acyl acceptor in combination with a highly selective lipase from Malassezia globosa (SMG1-F278N). This process enabled an unprecedented deacidification efficiency of up to 99.80% in a short time (6 h); the immobilized SMG1-F278N used in deacidification exhibited excellent operational stability and could be used for at least 10 consecutive batches without detectable loss in activity. Scale-up was performed under optimized conditions to verify the applicability of this process, and low-acid (0.08%) RBO with a high level of γ-oryzanol (27.8 g/kg) and γ-oryzanol accumulation fold (1.5) was obtained after molecular distillation at lower temperature (120 °C). Overall, we report a simplified and efficient procedure for the production of edible RBO from high-acid RBO.

Furan fatty acids – Beneficial or harmful to health?

Furan fatty acids are found in plants, algae, and fish, and reported to have some positive health benefits, including anti-oxidant and anti-inflammatory activities, and inhibition of non-enzymatic lipid peroxidation. A major metabolite of furan fatty acids, 3-carboxy-4-methyl-5-propyl-2-furanpropanoic acid (CMPF), has been reported to be increased in patients who progress from prediabetes to type 2 diabetes, although CMPF is not necessarily associated with impaired glucose metabolism. Other studies report that CMPF levels are lower in subjects with diabetes than control subjects. Plasma CMPF levels increase in subjects who consume fish or fish oil, and in patients with renal failure. It is not known where furan fatty acids are converted to CMPF and it is speculated that this might be a result of microbiome activity. The plasma levels reported for CMPF in healthy, diabetic and patients with renal disease vary by factors of more than 100-fold within each of these three groups, so measurement error appears to be limiting the ability to interpret studies. This review explores these controversies and raises questions about whether CMPF is a marker for healthy diets or indeed associated with diabetes and renal health. The review concludes that, on balance, furan fatty acids are beneficial for health.

Plasma coagulation factor VII activity and its correlates in healthy men

Objective:The aim of this study was to investigate the plasma coagulation factor VII activity and its correlates in healthy Australian men.Design:Cross-sectional study.Setting:Free living subjects.Subjects:A total of 139 healthy Australian males aged 20–55 y with widely varying intakes of individual fatty acids.Outcome measures:The concentration of phospholipid fatty acids and the parameters of biochemistry were analysed by standard methods. Citrated plasma factor VII activity was measured by using the ACL 200 system with commercially available kits.Results:In the stepwise multiple regression, controlled for age, body mass index and dietary groups, the two most important variables of factor VII activity were selected in the forward entry model with R 2=0.474 and P<0.0001 from 19 independent variables, which were significantly correlated with plasma factor VII activity in age-adjusted bivariate analysis where significance was considered at P<0.01. Plasma factor VII activity was strongly negatively correlated with prothrombin time (PT) (Std. Coeff. −0.550), and significantly positively correlated with plasma phospholipid (PL) stearic acid (Std. Coeff. 0.285).Conclusions:Increased factor VII activity was associated with shortening of PT. All types of fatty-acid concentrations of PLs were significantly positively correlated with factor VII activity; however, stearic acid was more potent than other fatty acids in healthy Australian men.Sponsorship:Meat Research Corporation of Australia.