Measurement of resistant starch content in cooked rice and analysis of gelatinization and retrogradation characteristics.

Digestion-resistant starch (RS) has many physiologic functions. The RS content is measured by enzymatically degrading flour samples according to the method of the Association of Official Analytical Chemists. Experiments have been performed with wheat, corn, and other grains, but there are no data for cooked rice grains in the form ingested by humans. Thus, we investigated a method to measure RS that is suitable for cooked rice grains using rice cultivars that are reported to differentially increase postprandial blood glucose in humans. Using a method for cooking individual rice grains and optimized enzyme reaction conditions, we established an RS measurement method. We also found that the amylopectin crystal condition affects the RS content measured using our method.

Effects of a meal rich in 1,3-diacylglycerol on postprandial cardiovascular risk factors and the glucose-dependent insulinotropic polypeptide in subjects with high fasting triacylglycerol concentrations.

It was previously reported that compared to triacylglycerol (TAG) oil, diacylglycerol (DAG) oil improves postprandial lipid response. However, the effects of DAG oil on postprandial hyperglycemia and incretin response have not yet been determined. In this study, the effects of DAG oil on both postprandial hyperlipidemia and hyperglycemia and the response to the glucose-dependent insulinotropic polypeptide (GIP) were studied. This randomized, double-blind, crossover study analyzed data for 41 individuals with high fasting triacylglycerol concentrations. The subjects ingested test meals (30.3 g of protein, 18.6 g of fat, and 50.1 g of carbohydrate) containing 10 g of DAG oil (DAG meal) or TAG oil (TAG meal) after fasting for at least 12 h. Blood samples were collected prior to and 0.5, 2, 3, 4, and 6 h after ingestion of the test meal. Postprandial TAG concentrations were significantly lower after the DAG meal compared with the TAG meal. Postprandial TAG, insulin, and GIP concentrations were significantly lower after the DAG meal compared with the TAG meal in 26 subjects with fasting serum TAG levels between 1.36 and 2.83 mmol/L. DAG-oil-based meals, as a replacement for TAG oil, may provide cardiovascular benefits in high-risk individuals by limiting lipid and insulin excursions.

Elimination of glycidyl palmitate in diolein by treatment with activated bleaching earth.

In this study, activated bleaching earth (ABE) was used to eliminate glycidyl esters from both triacyl- and diacylglycerol oils. To investigate the mechanism, glycerol dioleate containing glycidyl palmitate (GP) was treated with ABE and the fate of the GP was monitored by analyzing the feed, treated, and ABE-absorbed oils using a gas-liquid chromatograph equipped with a flame-ionized detector. GP was completely removed from both the treated and absorbed oils. This indicates that this treatment is useful for GE removal from diacylglycerol oil, although it was not achieved by absorption of GE on ABE but rather by modification of GP. The results of composition analysis demonstrate that GP is transformed to glycerol monopalmitate, glycerol palmitate oleate, and glycerol dipalmitate at a recovery rate of 99.1 ± 1.3 %. An increase in glycerol monooleate and trace amounts of free glycerol and fatty acids were also observed after treatment. The transformation is proposed to involve a ring-opening reaction of GP with water contained in the ABE and in the bulk oil followed by an interesterification reaction among the resultant monopalmitate and the glycerol dioleate of the bulk oil. All the generated compounds were simple acylglycerols and glycerol. Therefore, ABE treatment could be useful for GE removal during the manufacture of edible oils.

The short-term effect of diacylglycerol oil consumption on total and dietary fat utilization in overweight women.

Diacylglycerol (DAG) is a natural component of edible oils with metabolic characteristics distinct from those of triacylglycerol (TAG). Consumption of DAG oil (containing > 80% DAG) induces greater fat oxidation than consumption of TAG oil. We compared the effects of 4 days of DAG oil consumption with those of TAG oil consumption on total and dietary fat oxidation over 24 h in overweight women using a whole-room respiratory chamber. Overweight (BMI (kg/m²) ≥ 25) females participated in this double-blind, crossover-controlled trial. The subjects consumed test diets containing either TAG or DAG oil as 15% of their total caloric intake (mean test oil intake was 33.0 ± 3.1 g/day) during each 4-day treatment. Fat oxidation and energy expenditure were measured in a respiratory chamber on the 4th day of each treatment. Compared with TAG oil, DAG oil consumption significantly increased total fat oxidation and dietary fat oxidation in overweight subjects. Total energy expenditure (TEE) and carbohydrate (CHO) oxidation did not significantly differ between DAG oil and TAG oil consumption in overweight subjects. Compared with TAG oil, DAG oil consumption enhanced total fat oxidation and dietary fat oxidation in overweight subjects. The enhanced fat metabolism in overweight subjects that consumed DAG oil partly explains the greater loss of body weight and body fat related to DAG oil consumption in weight-loss studies.

Serum retinol, alpha-tocopherol, and beta-carotene levels are not altered by excess ingestion of diacylglycerol-containing plant sterol esters.

BACKGROUND: Diacylglycerol (DAG) suppresses the postprandial increase in serum triglycerides, and has antiobesity effects. On the other hand, plant sterol esters (PSE) lower serum cholesterol levels in hypercholesterolemia. Thus, DAG-containing PSE (PSE/DAG) would be expected to maintain an appropriate serum cholesterol level and decrease the risk of arteriosclerotic disorders. Several recent studies, however, report negative effects of PSE on serum fat-soluble (pro)vitamin levels. The objective of this study was to investigate the effect of PSE/DAG on serum retinol, beta-carotene, and alpha-tocopherol levels using a threefold excess of the effective dose obtained in our previous study. METHODS: A randomized placebo-controlled double-blind parallel study was performed in healthy and mildly hypercholesterolemic subjects, in which the subjects ingested 1.2 g PSE/30 g DAG for 2 weeks in the form of mayonnaise-type products. Triacylglycerol (TAG) mayonnaise was used as a control. RESULT: There were no subjective adverse effects or changes in serum retinol, alpha-tocopherol, and beta-carotene levels, abdominal symptoms, hematologic values, or blood biochemical values. CONCLUSION: Ingestion of a threefold excess of PSE/DAG for 2 weeks had no adverse effects compared to ingestion of conventional TAG mayonnaise.

Dose-dependent cholesterol-lowering effect of a mayonnaise-type product with a main component of diacylglycerol-containing plant sterol esters.

OBJECTIVE: The objective of this study was to investigate the effective dose of plant sterol ester (PSE)-enriched diacylglycerol (DAG) oil for healthy subjects with mild hypercholesterolemia. METHODS: A randomized, placebo-controlled, double-blind, parallel study was performed in patients with mild hypercholesterolemia; 0.0, 0.3, 0.4, and 0.5 g of PSE was dissolved in 15 g of a DAG-containing mayonnaise-type product; and 15 g/d of the product was administered 4 wk. RESULTS: Total serum cholesterol levels were significantly decreased as a result of the ingestion of at least 0.4 g/d of PSE, and serum low-density lipoprotein cholesterol levels were significantly decreased by the ingestion of at least 0.3 g/d of PSE. CONCLUSIONS: Daily ingestion of 15 g of DAG plus mayonnaise containing at least 0.4 g/d of PSE for 4 wk may significantly decrease cholesterol.