Measurement of α-Amylase Activity in White Wheat Flour, Milled Malt, and Microbial Enzyme Preparations, Using the Ceralpha Assay: Collaborative Study

This study was conducted to evaluate the method performance of a rapid procedure for the measurement of α-amylase activity in flours and microbial enzyme preparations. Samples were milled (if necessary) to pass a 0.5 mm sieve and then extracted with a buffer/salt solution, and the extracts were clarified and diluted. Aliquots of diluted extract (containing α-amylase) were incubated with substrate mixture under defined conditions of pH, temperature, and time. The substrate used was nonreducing end-blocked p-nitrophenyl maltoheptaoside (BPNPG7) in the presence of excess quantities of thermostable α-glucosidase. The blocking group in BPNPG7 prevents hydrolysis of this substrate by exo-acting enzymes such as amyloglucosidase, α-glucosidase, and β-amylase. When the substrate is cleaved by endo-acting α-amylase, the nitrophenyl oligosaccharide is immediately and completely hydrolyzed to p-nitrophenol and free glucose by the excess quantities of α-glucosidase present in the substrate mixture. The reaction is terminated, and the phenolate color developed by the addition of an alkaline solution is measured at 400 nm. Amylase activity is expressed in terms of Ceralpha units; 1 unit is defined as the amount of enzyme required to release 1 μmol p-nitrophenyl (in the presence of excess quantities of α-glucosidase) in 1 min at 40°C. In the present study, 15 laboratories analyzed 16 samples as blind duplicates. The analyzed samples were white wheat flour, white wheat flour to which fungal α-amylase had been added, milled malt, and fungal and bacterial enzyme preparations. Repeatability relative standard deviations ranged from 1.4 to 14.4%, and reproducibility relative standard deviations ranged from 5.0 to 16.7%.

Consumption of a whey protein-enriched diet may prevent hepatic steatosis associated with weight gain in elderly women

BACKGROUND AND AIMS

Protein consumption has been associated with cardio-metabolic benefits, including weight loss and improved insulin sensitivity, and may have potential benefits for individuals with fatty liver disease (FLD). We investigated the effect of increasing dietary protein intake from whey relative to carbohydrate on hepatic steatosis.

METHODS AND RESULTS

A two-year randomized, double-blind, placebo-controlled trial of 30 g/day whey protein-supplemented beverage (protein) or an energy-matched low-protein high-carbohydrate beverage (control) for cardio-metabolic and bone health in 219 healthy elderly women, recruited from the Western Australian general population. Hepatic steatosis was quantified using computed tomographic liver-to-spleen (L/S) ratio. FLD was defined as liver-to-spleen difference <10 Hounsfield units. At baseline, FLD prevalence was 11.4%. Control and protein groups were similar in body mass index (BMI), insulin resistance, L/S ratio and FLD prevalence at baseline. At two-years, dietary protein increased by 20 g in the protein, but not the control, group. Total energy intake and physical activity remained similar between groups. At two-years, BMI and FLD prevalence increased in both groups, with no between group differences. L/S ratio increased in control, but not protein, group at two-years, with no between group differences. In a within group comparison, change in BMI correlated with changes in L/S ratio in control (r = 0.37, P = 0.0007), but not with protein group (r = 0.04, P = 0.73).

CONCLUSION

Increasing dietary protein intake from whey relative to carbohydrate does not reduce weight, hepatic steatosis or the prevalence of FLD in elderly women. However, it may prevent worsening of hepatic steatosis associated with weight gain.

CLINICAL TRIALS REGISTRATION

Australian New Zealand Clinical Trials Registry (Registration no. ACTRN012607000163404).

Effects of incorporating germinated brown rice on the antioxidant properties of wheat flour chapatti

Brown rice after germinating for 24 and 48 h was milled into flour and incorporated in whole wheat flour at a level of 10% to prepare chapattis. The objective was to use chapatti as a delivery vehicle for germinated brown rice. The flour blends and chapattis made from the flour blends were evaluated for their antioxidant properties. Incorporating germinated brown rice flour increased the total phenolic content of the flour blend from 1897 to 2144 µg FAE/g. The total flavonoids content increased significantly from 632.3 to1770.9 µg CAE/g and metal chelating activity significantly increased by 71.62%. Antioxidant activity increased significantly by the addition of brown rice flour and addition of 24- and 48-h germinated brown rice flour further increased the antioxidant activity significantly. The total phenolic content and total flavonoids content decrease significantly in all the blends after baking the flour into chapatti. A decrease of 3% to 29% was observed in the total phenolic content and a decrease of 25% to 42% was observed in the total flavonoids content. However, baking of the flour blends into chapatti increased the reducing power, metal chelating activity by three folds and antioxidant activity from 64% to 104%.

Effects of Prima gland clover (Trifolium glanduliferum Boiss cv. Prima) consumption on sheep production and meat quality

Gland clover (Trifolium glanduliferum Boiss) is a recently introduced and released clover species for use in Mediterranean agricultural systems in southern Australia. There is little information on the expected animal production from this pasture plant although it is known to contain coumarins. Coumarins may have a direct effect on the production of grazing ruminants through a reduction in feed intake and may also have the ability to influence the flavour and odour of meat. In this study, Merino hogget ewes were grazed on eight 0.5 ha replicate plots sown to monocultures of either Prima gland clover or Dalkeith subterranean clover (Trifolium subterraneum ssp. subterraneum L.). The Prima gland clover was estimated to contain between 80 and 300 mg coumarin/kg dry matter. Three sheep were allocated to the plots on 7 September and 1 sheep from each plot was slaughtered on 29 September. Two additional sheep were allocated to the plots on 28 September and another 2 on 19 October. At the end of the experiment on 8 November, each plot contained 2 sheep that had grazed for 3, 6 or 9 weeks. All sheep were slaughtered at this time. The 2 sheep that remained on the plots from 7 September to 8 November were used for the comparison of animal production between the 2 clover species. Following slaughter, measurements were made of carcass characteristics and meat eating quality. The liveweight gain and wool growth of the 2 treatments were similar over the 9 weeks, however, the sheep on the Prima gland clover plots grew faster over the first 3 weeks. The faster growth rate is consistent with a higher in vitro digestibility of the Prima gland clover at this time. The similarity in feeding value of the 2 clover species indicates that there was no depression in feed intake associated with the Prima gland clover. There were some small significant differences in meat eating quality between the groups. Meat from sheep grazing the Prima gland clover was drier and had a more pleasant taste. These differences are unlikely to be large enough to have any commercial significance. The results indicate that the Prima gland clover has a feeding value at least equivalent to the Dalkeith subterranean clover and that, under the conditions of this experiment, the coumarin concentrations in the Prima gland clover are not high enough to affect either feed intake or the flavour and odour of meat.