Effect of pyruvic acid and ascorbic acid on stability of 3‐deoxyanthocyanidins

BACKGROUND: 3‐Deoxyanthocyanins are a rare class of plant pigments primarily found in sorghum and known to possess distinct chemical and bioactive properties. They have potential as natural food colourants. This work investigates how 3‐deoxyanthocyanin pigments react with pyruvic acid and their stability in the presence of ascorbic acid. RESULTS: Substitution at C‐5 was the major determinant of the mechanism of 3‐deoxyanthocyanidin complexation with pyruvic acid: hydroxyl substitution favoured cyclic condensation, whereas methoxyl substitution favoured oxidative ring contraction. Pure 3‐deoxyanthocyanidins generally showed poor stability in the presence of 500 mg L^?1 ascorbic acid at pH 2.0 and 3.2 but were stable at pH 5.0; pyruvic acid improved their stability at pH 2.0 and 3.2 and enhanced their colour intensity at pH 5.0. Crude sorghum pigment extract was very stable in the presence of ascorbic acid: 31% colour loss at pH 2.0; 1.9‐ and 1.3‐fold increases in colour intensity at pH 3.2 and 5.0 respectively. In contrast, red cabbage pigment lost 30–85% of its colour in the presence of ascorbic acid under the conditions used in the study. CONCLUSION: Crude sorghum pigments are very stable in the presence of ascorbic acid and may be useful as natural food colourants. Copyright © 2008 Society of Chemical Industry     

α‐Eleostearic acid is more effectively metabolized into conjugated linoleic acid than punicic acid in mice

BACKGROUND: The objective of this study was to investigate the metabolism of α‐eleostearic acid (α‐ESA, cis9,trans11,trans13‐18:3) and punicic acid (PA, cis9,trans11,cis13‐18:3) and to compare the relative conversion efficiency of these fatty acids into conjugated linoleic acids (CLAs) in mice. RESULTS: Twenty‐four male ICR mice were fed either a control diet or one of two experimental diets supplemented with 10 g kg^?1α‐ESA or PA in the form of triacylglycerols for 6 weeks. The accumulation of PA in all tissues examined was significantly higher than α‐ESA; in both groups it was found that cis9,trans11‐conjugated linoleic acid (cis9,trans11‐18:2) was detected in all tissues examined. The relative conversion rate of α‐ESA into cis9,trans11‐18:2 was significantly higher than that of PA. The highest conversion rate of α‐ESA was found in adipose tissue (91.8%), spleen (91.4%) and kidney (90.7%), and the lowest in the heart (84.6%). The highest conversion rate of PA occurred in the liver (76.2%) and the lowest occurred in the heart (54.5%). CONCLUSION: The present results indicate that both α‐ESA and PA are effectively metabolized into cis9,trans11‐18:2 in mice. These conjugated dietary fatty acids might be useful sources of CLAs in tissues owing to the natural abundance of α‐ESA and PA in some seeds. Copyright © 2009 Society of Chemical Industry     

Effects of poly‐γ‐glutamic acid on the physicochemical characteristics of skim milk yoghurt

The physicochemical and sensory properties of skim milk yoghurts containing poly‐γ‐glutamic acid (PGA) at different levels (0.0025, 0.005 and 0.01%) were evaluated. Addition of PGA up to 0.01% to reconstituted skim milk (11%, w/v) did not affect the growth of lactic acid bacteria or the development of titratable acidity in yoghurt, whereas full‐fat control yoghurt had reduced acid production. No changes were found in viable cell counts of PGA yoghurts during storage (4 weeks at 4 °C). The addition of PGA (0.005%) significantly decreased syneresis in skim milk yoghurt and did not cause any undesirable effects in sensory acceptability.     

Plasma phospholipids n‐3 polyunsaturated fatty acid is associated with metabolic syndrome

The relationship between n‐3 PUFA and metabolic syndrome (MS) is not clear. The aim of this study was to examine relationships between plasma phospholipids (PL) n‐3 PUFA and MS in Chinese subjects. Nine hundred and twenty‐nine subjects were recruited in Hangzhou, China. Two hundred and ten (183 males, 27 females) with MS and 719 (545 males, 174 females) healthy subjects were identified in this cross‐sectional study. The prevalence of MS in females (24.56%) was significantly higher than that in males (10.04%) in this population. Total PUFA (p<0.001), n‐3 PUFA (p<0.001), and n‐3:n‐6 (p<0.001) were significantly lower in MS subjects compared to healthy subjects. Plasma phospholipid (PL), n‐3 PUFA was significantly inversely associated with MS (p=0.013). In addition, subjects with high levels of PL total fatty acids (FA) had a more than threefold higher likelihood of MS (OR=3.44, 95% CI=1.60–7.39) than the subjects with low levels of PL total FA. Our results suggest that plasma PL n‐3 PUFA was significantly inversely associated with MS, while high total FA were positively associated with MS in Chinese.     

HPLC determination of γ‐aminobutyric acid in Chinese rice wine using pre‐column derivatization

γ‐Aminobutyric acid (GABA) is a major functional ingredient in Chinese rice wine. A new HPLC method for determining GABA using pre‐column derivatization with dansyl chloride was developed. The HPLC operating conditions were as follows: a Hypersil ODS2 C₁₈ column; mobile phase, methanol and water (1:1); gradient elution; absorption at 254 nm; flow rate, 1 mL/min; pH 9; and column temperature, 30 °C. Under optimal HPLC conditions, the linear equation was y = 3.5 × 10^?7x ? 0.014. The precision (relative standard deviation, RSD) was 0.54%, the stability (RSD) was 0.21%, the recovery ratio was 97.4% and reproducibility (RSD) was 1.57%. This new method appears to be sensitive, accurate, convenient, steady and relatively fast. The results suggest that the new method is also more reliable. Copyright © 2015 The Institute of Brewing & Distilling     

Improved physical stability of docosahexaenoic acid and eicosapentaenoic acid encapsulated using nanoliposome containing α‐tocopherol

This study aimed to develop a nanoliposomal formulation containing α‐tocopherol loaded with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and to characterise the formulation by its physical stability. For this purpose, different nanoliposomal formulations with dipalmitoyl phosphocholine were prepared using a modified thin‐film hydration method and evaluated by particle size, polydispersity index (PDI), transmission electron microscopy, differential scanning calorimetry and determining the encapsulation efficiencies of DHA and EPA. A physical stability study was conducted by investigating the change in the vesicle encapsulation efficiency, particle size, PDI and shape when stored at 4, 30 and 40 °C for 3 months. High encapsulation efficiency of DHA and EPA (89.1% ± 0.6% and 81.9% ± 1.4%) and appropriate particle size (82 ± 0.8 nm) were obtained for liposomes composed of α‐tocopherol. The optimum formulation was stable for 90 days when kept at 4 °C. This study demonstrated that α‐tocopherol had a protective effect on the physical stability of the nanoliposomes containing DHA and EPA.     

Structural characterisation of β‐cyclodextrin crosslinked by adipic acid

This study was conducted to investigate the structural characterisation of β‐cyclodextrin (β‐CD) crosslinked by adipic acid. β‐CD was treated with different concentrations (0%, 5%, 10% and 15%, w/v) of adipic acid. Different instruments, such as scanning electron microsope (SEM), Fourier‐transform infrared (FT‐IR) spectroscopy and ¹H and ¹³C nuclear magnetic resonance (NMR) spectra were used to find out chemical structure in the crosslinked β‐CD. SEM analysis suggested that crosslinking β‐CD with 15% adipic acid changed the original morphology and considerably increased the particle size of the raw material. FT‐IR spectroscopy data showed that an intensive absorption band at 1706 cm^?1 was present in the β‐CD samples treated with 10% and 15% adipic acid, indicating a crosslinking between hydroxyl groups of β‐CD and carboxyl groups of adipic acid. NMR spectra revealed that the ester linkages between hydroxyl groups of β‐CD and carboxyl groups of adipic acid were formed after crosslinking of β‐CD with adipic acid.     

Effects of oxidised linoleic acid on the formation of Nε‐carboxymethyl‐lysine and Nε‐carboxyethyl‐lysine in Maillard reaction system

This study investigated the effects of oxidised linoleic acid (18:2) on N^ε‐carboxymethyl‐lysine (CML) and N^ε‐carboxyethyl‐lysine (CEL) formation in Maillard reaction systems. Model systems of lysine/glucose (L/G), lysine/18:2 (L/18:2), lysine/18:2/glucose (L/18:2/G), myofibrillar protein/glucose (MFP/G), MFP/18:2 and MFP/18:2/G were maintained at 37 °C for 6 weeks. The results showed that CML/CEL contents in L/G (6.99 and 0.96 mmol mol^?1 lysine, respectively) were significantly higher than those in L/18:2/G (1.43 and 0.41 mmol mol^?1 lysine, respectively), and there is a small amount of CML/CEL generation in L/18:2. However, the CML/CEL levels in MFP/G (197.2 and 83.8 ng mg^?1 protein, respectively) were markedly lower than those in MFP/18:2/G (283.2 and 118.5 ng mg^?1 protein, respectively). 18:2 favours the formation of CML/CEL in MFP/18:2/G, not in L/18:2/G. All these findings indicated that the role of 18:2 on CML/CEL formation in Maillard reaction system was complex, and depended on CML/CEL formation rate and substrate types (lysine or lysine residue in protein).