2‐Furoylmethyl amino acids,hydroxymethylfurfural, carbohydrates and β‐carotene as quality markers of dehydrated carrots

BACKGROUND: Processing of vegetables in the food industry usually includes dehydration as a preservation process. Industrial convective air drying of carrot can involve steam blanching of the raw product after peeling and cutting, and different stages of dehydration (first space, second space and final drying). Although the shelf‐life of carrot is significantly extended, important changes in its chemical composition can take place during dehydration since high temperatures and long times are used. This research is a preliminary study to evaluate the usefulness of β‐carotene, carbohydrates, hydroxymethylfurfural (HMF) and 2‐furoylmethyl amino acids (2‐FM‐AA) as quality markers of dehydrated carrots. RESULTS: A considerable decrease in β‐carotene and reducing carbohydrates was observed during dehydration. HMF, absent in raw carrots, increased during the whole drying process and the highest formation was found during the steam blanching stage. 2‐FM‐AA of lysine, arginine, γ‐aminobutyric acid and alanine were progressively originated up to the second space and decreased during the final drying. CONCLUSION: The combined use of HMF and 2‐FM‐AA seems to be advantageous for the assessment of the optimal processing conditions to obtain high‐quality dehydrated carrots. Copyright © 2008 Society of Chemical Industry     

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.     

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.     

Screening of β‐Glucosidase and β‐Xylosidase Activities in Four Non‐Saccharomyces Yeast Isolates

The finding of new isolates of non‐Saccharomyces yeasts, showing beneficial enzymes (such as β‐glucosidase and β‐xylosidase), can contribute to the production of quality wines. In a selection and characterization program, we have studied 114 isolates of non‐Saccharomyces yeasts. Four isolates were selected because of their both high β‐glucosidase and β‐xylosidase activities. The ribosomal D1/D2 regions were sequenced to identify them as Pichia membranifaciens Pm7, Hanseniaspora vineae Hv3, H. uvarum Hu8, and Wickerhamomyces anomalus Wa1. The induction process was optimized to be carried on YNB‐medium supplemented with 4% xylan, inoculated with 106 cfu/mL and incubated 48 h at 28 °C without agitation. Most of the strains had a pH optimum of 5.0 to 6.0 for both the β‐glucosidase and β‐xylosidase activities. The effect of sugars was different for each isolate and activity. Each isolate showed a characteristic set of inhibition, enhancement or null effect for β‐glucosidase and β‐xylosidase. The volatile compounds liberated from wine incubated with each of the 4 yeasts were also studied, showing an overall terpene increase (1.1 to 1.3‐folds) when wines were treated with non‐Saccharomyces isolates. In detail, terpineol, 4‐vinyl‐phenol and 2‐methoxy‐4‐vinylphenol increased after the addition of Hanseniaspora isolates. Wines treated with Hanseniaspora, Wickerhamomyces, or Pichia produced more 2‐phenyl ethanol than those inoculated with other yeasts.     

SO32– effects the 5‐hydroxymethyl‐2‐furaldehyde content in ammonium sulphite–glucose solutions

Effects of sulphite concentration on ammonium sulphite–glucose solution’s pH value and browning intensity were studied. Results showed both the solution’s pH value and browning intensity changed significantly in relation to the increases in SO₃^2– concentration. 5‐hydroxymethyl‐2‐furaldehyde was measured by nuclear magnetic resonance and HPLC. This study indicates that the changes of 5‐hydroxymethyl‐2‐furaldehyde content accompanied changes in browning intensity. Moreover, adding ammonium sulphite significantly reduced the 5‐hydroxymethyl‐2‐furaldehyde content. The mechanism may be that SO₃^2– limits the formation of N‐glucosamine, an important precursor for forming 5‐hydroxymethyl‐2‐furaldehyde, by reacting with glucose, which could not form an imine in further reaction.     

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.     

High Concentration of Epigallocatechin‐3‐Gallate Increased the Incidences of Arrhythmia and Diastolic Dysfunction Via β2‐adrenoceptor

Epigallocatechin‐3‐gallate (EGCG) is the major and most potent representative in green tea, which has been proved to modulate myocardial contractility. Whether EGCG has some negative effects on cardiac function is not known. In the present study, we investigated the effects of EGCG at different doses on cardiac contraction and explored whether β₂‐adrenoceptor (β₂AR) was involved in EGCG‐induced cardiac effects. Isolated rat hearts were mounted on the Langendorff system and perfused with different concentrations of EGCG in low or normal calcium Krebs–Henseleit (KH) buffer. The contraction of hearts was measured. Ventricular myocytes were cultured with EGCG and isoprenaline (ISO, 10^?7 M) for 12 h. ICI118,551 (55 nM) was used to inhibit β₂AR. Cardiomyocyte shortening, viability, and responsiveness to ISO (10^?9 M) were measured. EGCG dose dependently enhanced contractility of perfused heart in low calcium KH buffer. In the normal calcium KH buffer, EGCG at low dose (20 μM) increased heart contraction, while at high dose (50 μM), it increased the incidences of arrhythmia and diastolic dysfunction. In isolated ventricular myocytes, EGCG at the concentration of 0.001 to 1.0 μΜ did not affect their contraction. However, the responsiveness to ISO and the survival of myocytes were increased by EGCG (0.01 μM). The increased responsiveness was partially abolished by ICI118,551. The data obtained in this study demonstrated that EGCG at low dose conferred cardioprotection, yet at high dose increased the incidences of arrhythmia and diastolic dysfunction. β₂AR was involved in EGCG‐induced cardiac effects.     

Breeding of lipoxygenase‐1‐less malting barley variety ‘Satuiku 2 go’

The lipoxygenase‐1‐less (LOX‐less) trait has positive effects on beer quality, in particular, improvement of flavour stability related to the reduction of beer‐deteriorating substances such as trans‐2‐nonenal. ‘Ryohfu’ is the only spring‐sown malting barley variety grown in Hokkaido, located in the northern part of Japan, and has been used in the Japanese brewing industry for over 20 years. ‘Satuiku 2 go’ was developed as the first LOX‐less malting barley variety in Japan by successive back‐crossing with molecular marker‐assisted selection to introduce the LOX‐less trait into the recurrent parent ‘Ryohfu’. The agronomic performance and general malt quality of ‘Satuiku 2 go’ were almost equivalent to those of ‘Ryohfu’. Wort and beer analyses at the pilot‐scale brewing trial indicated that the LOX‐less trait had little effect on the general characteristics. In contrast, the beers made from ‘Satuiku 2 go’ malt exhibited reduced levels of trans‐2‐nonenal and trihydroxyoctadecenoic acid. The sensory evaluation demonstrated the superiority of ‘Satuiku 2 go’ beers stored under differing conditions in terms of staleness. It can be concluded that the LOX‐less trait was effective in different genetic backgrounds of the recurrent parents used for the development of LOX‐less malting barley varieties. Copyright © 2018 The Institute of Brewing & Distilling