Degradation of N‐(1‐Deoxy‐d‐xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐xylulos‐1‐yl)proline using thermal treatment

The formation and degradation of N‐(1‐Deoxy‐d ‐xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d ‐xylulos‐1‐yl)proline, derived from the secondary amine Maillard reaction in xylose‐amino acid model solutions, were detailed in this study. The identification and quantitative analysis of N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline were carried out using high‐performance anion‐exchange chromatography and high‐performance liquid chromatography. The formation of intermediate and advanced products derived from N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline was also tested using an UV‐Vis spectrophotometer to gain a better comparing of the degradation process of the two important Maillard reaction products using thermal treatment. Results showed that the degradation of N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine was more significant than N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline. Moreover, xylose was tested in the degradation products of both N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)glycine and N‐(1‐Deoxy‐d‐ xylulos‐1‐yl)proline, which indicated that the degradation of N‐substituted 1‐amino‐1‐deoxyketoses was a reversible reaction to form reducing sugar.     

The effect of pH and calcium ion on rheological behaviour of β‐lactoglobulin‐basil seed gum mixed gels

Effect of pH (4.5–7.5) and Ca²⁺ (0.01–0.5 m ) on gelation of single and mixed systems of 10% β‐lactoglobulin (BLG) and 1% basil seed gum (BSG) was investigated. The gelling point of BLG and BSG gels was strongly pH‐dependent, and stiffer gels formed at higher pH. The BLG gels were formed upon heating to 90 °C and reinforced on cooling to 20 °C; however, the gelation of BSG occurred at temperatures below 70 °C. By increasing Ca²⁺ concentration, storage modulus of BLG and BSG gels were increased, although pH had a greater effect than Ca²⁺. In contrast, mixed systems showed two distinct types of behaviour: BLG gel formation and BSG network, suggesting that phase‐separated gels were formed. In addition, higher strength was obtained for BLG‐BSG mixture at higher Ca²⁺ concentration.     

In vivo effect of oat cereal β‐glucan on metabolic indexes and satiety‐related hormones in diet‐induced obesity C57‐Bl mice

This study explored the dose‐dependent effect of oat cereal β‐glucan on improving metabolic indexes of obesity mice. C57‐Bl mice were randomized to chow diet (N) group and high fat diet group and other three doses of oat β‐glucan groups (low β‐glucan, medium β‐glucan, and high β‐glucan). Energy intake, glucose, lipids, and appetite related hormones were tested. Dose‐dependent relation was observed on oat β‐glucan doses and body weight change, average energy intake, total cholesterol, HDL cholesterol, plasma neural peptide Y, arcuate neural peptide Y mRNA, and arcuate neural peptide Y receptor 2 mRNA level. Oat β‐glucan helped to increase plasma peptide Y‐Y and intestine peptide Y‐Y expression in obesity mice.     

Formation of protein adducts of 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine in cooked foods

Heterocyclic amines (HCAs) are mutagenic and carcinogenic compounds found in cooked meat and fish. Although HCAs are known to form adducts with protein after metabolic activation, adduct formation during cooking has not been elucidated. In this study, we showed that 2‐amino‐1‐methyl‐6‐phenylimidazo[4,5‐b]pyridine (PhIP) is released from high molecular weight compounds by acid or enzymatic hydrolysis of cooked foods. Formation of free and protein adduct forms of PhIP was dependent on cooking temperature and time, and PhIP–protein adducts were estimated to form after formation of free PhIP. We also demonstrated that PhIP–protein adduct is formed by heating of PhIP and albumin as a model protein. A new adduct peak including [M+H]⁺ (m/z=225) of PhIP as a fragment ion was detected in the high molecular weight fraction of heat‐treated protein by LC–MS analysis. From model experiments by heating of PhIP and amino acids, the adduct was estimated to be produced by condensation of the amino group of PhIP and the carboxyl group of protein. PhIP–protein adducts were detected in several cooked meat and fish at ng/g food level as PhIP content. These results suggest that food‐borne protein adducts of HCAs may influence human HCA exposure and carcinogenic risk.     

Investigation of the interaction between (−)‐epigallocatechin‐3‐gallate with trypsin and α‐chymotrypsin

Tea polyphenol (TP) inhibits digestive enzymes and reduces food digestibility. To explore the interaction between TP with digestive enzymes, bindings of ‐epigallocatechin‐3‐gallate (EGCG) to trypsin and α‐chymotrypsin were studied in detail using fluorescence, resonance light‐scattering, circular dichroism, fourier transform infrared spectroscopy methods and protein‐ligand docking. The binding parameters were calculated according to Stern–Volmer equation, and the thermodynamic parameters were determined by the van't Hoff equation. The results indicated that EGCG was capable of binding trypsin and α‐chymotrypsin with high affinity, resulting in a change of native conformation of these enzymes. EGCG had a greater influence on the structure of α‐chymotrypsin than trypsin. This study can be used to explain the binding interaction mechanism between TP and digestive enzymes.     

Characterization of the Supermolecular Structure of Polydatin/6‐O‐α‐Maltosyl‐β‐cyclodextrin Inclusion Complex

Polydatin is the main bioactive ingredient in many medicinal plants, such as Hu‐zhang (Polygonum cuspidatum), with many bioactivities. However, its poor aqueous solubility restricts its application in functional food. In this work, 6‐O‐α‐Maltosyl‐β‐cyclodextrin (Malt‐β‐CD), a new kind of β‐CD derivative was used to enhance the aqueous solubility and stability of polydatin by forming the inclusion complex. The phase solubility study showed that polydatin and Malt‐β‐CD could form the complex with the stoichiometric ratio of 1:1. The supermolecular structure of the polydatin/Malt‐β‐CD complex was characterized by ultraviolet–visible spectroscopy (UV), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffractometry (XRD), thermogravimetric/differential scanning calorimetry (TG/DSC), and proton nuclear magnetic resonance (¹H‐NMR) spectroscopy. The changes of the characteristic spectral and thermal properties of polydatin suggested that polydatin could entrap inside the cavity of Malt‐β‐CD. Furthermore, to reasonably understand the complexation mode, the supermolecular structure of polydatin/Malt‐β‐CD inclusion complex was postulated by a molecular docking method based on Autodock 4.2.3. It was clearly observed that the ring B of polydatin oriented toward the narrow rim of Malt‐β‐CD with ring A and glucosyl group practically exposed to the wide rim by hydrogen bonding, which was in a good agreement with the spectral data.     

(+)‐Catechin and (−)‐epicatechin levels of concentrated and ready‐to‐drink grape juices through storage

Commercial concentrated Concord (CCJ) and Isabel (CIJ) grapes juices were stored at 4–5 °C while pasteurised ready‐to‐drink juices of the same grape cultivars (PCJ and PIJ) were kept at 20–25 °C under indirect light for 10 months, simulating industrial storage conditions. (+)‐catechin preservation during storage ranged between 63% (PCJ) and 52% (PIJ); (?)‐epicatechin retention was of 32% (CCJ) and 15% (CIJ). Total phenols retention ranged from 93% (CCJ) to 84% (PCJ) and radical scavenging activity (RSA) from 87% (PIJ) to 85% (CCJ and PCJ). Concentrated juices showed higher monomeric flavan‐3‐ols amounts and CCJ depicted superior phenolic contents. PIJ yielded the highest RSA during storage per phenolic unit. Process and storage impacted flavan‐3‐ols and not total phenolics and RSA during 10‐month ageing.     

In vitro culture of Pandanus amaryllifolius and enhancement of 2‐acetyl‐1‐pyrroline,the major flavouring compound of aromatic rice,by precursor feeding of L‐proline

Shoots, plantlets and semi‐differentiated callus (SDC) cultures of Pandanus amaryllifolius capable of producing high levels of basmati rice flavour were established in vitro using Murashige and Skoog nutrient medium. A total of 10% of the initial explants responded to produce shoot cultures in the presence of benzylamino purine (BAP) (0.5 mg L^?1) and glutamine (100 mg L^?1). Leaf explants and basal portions of shoots produced SDC whereas elongated in vitro shoots could be continuously multiplied, using BAP (1.5 mg L^?1) and kinetin (Kn) (1.0 mg L^?1), and rooted in half‐strength medium for ex vitro cultivation leading to a process of micropropagation. Steam‐distillation extraction (SDE) followed by gas chromatography‐mass spectrometry (GC‐MS) analysis of various cultured organs and spent liquid medium used for SDC revealed the presence of 2‐acetyl‐1‐pyrroline (2‐AP) to various extents. This 2‐AP compound has been identified as the major flavouring compound of scented basmati and other scented rice varieties. 2‐AP was found to be highest, on a fresh weight basis, in SDC (19.7 mg kg^?1) on the 40th day, whereas in vitro roots, shoots and field leaves (of one‐year‐old plant) had lower levels of 15, 6.8 and 14 mg kg^?1, respectively. Further enhancement of 2‐AP in SDC using precursor was possible by feeding into medium 1 mmol L^?1 of L ‐proline where a highest level of 21.67 ppm of 2‐AP accumulated on the seventh day whereas a higher level of 2 mmol L^?1 of L ‐proline suppressed 2‐AP levels. The present report is the first on the tissue culture studies of P. amaryllifolius where continuous production of plantlets as well as synthesis of high levels of 2‐AP has been documented. Copyright © 2005 Society of Chemical Industry     

Development of corn starch‐gum bread for phenylketonuria patients

Phenylketonuria (PKU) is an inherited metabolic disease resulting from an enzyme defect that leads to failure to utilize phenylalanine and it is the most common aminoacidopathy in Turkey. There are a considerable number of individuals suffering from PKU and they need special food formulations, but the choice of special foods is limited for these people. Since the bread is the staple food in Turkey, the primary aim of this study was to develop bread formulation and procedure for PKU patients by using materials available in Turkey. To be able to produce low phenylalanine starch‐gum bread, five different commercial food grade gums were added to the corn starch at 1, 2, and 3% addition levels. The addition of surfactant brought about remarkable changes in the starch dough. Loaf of the best overall quality was produced with one of the gums (xanthan gum and carrageenans mixture) at the addition level of 2%, water addition level of 105%, the final proof time of 110 min and the temperature of 30°C when compared with the other gum breads. As a result, a basic formula and procedure for preparing a desirable corn starch‐gum bread was reported for PKU patients.     

In vitro Digestibility of Cross‐Linked Starches – RS4

In vitro digestibility of cross‐linked starches (RS4 type), which were prepared from wheat, corn, rice, potato, and high‐amylose corn starches, was determined by Prosky AOAC and pancreatin gravimetric (P/G) methods. The RS levels of RS4 starches obtained by the AOAC method were higher than those by the P/G method. Pronase treatment before digestion with heat‐stable α‐amylase (AOAC method) gave similar RS levels as those by P/G method. The shapes of residues after digestion by the AOAC method were not different from untreated ones, but those after digestion by the P/G method showed irregular and fluffy forms. It was found that the P/G method provided more exhaustive digestion of RS4 starches than the AOAC method.