Thermal degradation of all-trans-β-carotene in the presence of phenylalanine

Solutions of all-trans-β-carotene in liquid paraffin were stirred under air at 210°C for 15 min in the presence and absence of various amino acids. After cooling, the absorbance values at 460 nm of model systems containing all-trans-β-carotene and phenylalanine, cysteine or tryptophan were 34–58 times higher than that obtained on heating in the absence of an amino acid. Based on absorbance values at 420 nm, 86% of the coloured material present on heating the all-trans-β-carotene-phenylalanine model system at 210°C for 15 min was retained by the liquid paraffin on methanol extraction. The liquid paraffin phase remaining after methanol extraction was analysed by reverse-phase HPLC and three major components were identified as all-trans-β-carotene and two degradation products of all-trans-β-carotene, ie 9-cis-β-carotene and a furanoid diepoxy derivative. None could be detected on heating all-trans-β-carotene alone, suggesting that its degradation was retarded on heating in the presence of phenylalanine.     

KINETICS OF β-GLUCAN DEGRADATION IN WORT BY EXOGENOUS β-GLUCANASES TREATMENT

Three commercial β-glucanases, one bacterial (Cereflo 200L from Novo) and two fungal (Biobeta from Gist-Brocades and Filtrase from Biocon) have been studied with regard to the hydrolysis of β-glucan in sweet and hopped wort. At temperatures below 70°C these processes follow first order kinetics with rate constants being directly proportional to the enzyme concentrations. The rate constant for bacterial β-glucanase Cereflo 200L shows a negative dependence on temperature but positive with wort pH, whereas the reverse is the case for the two fungal β-glucanases. Within the ranges of pH and temperature tested the bacterial β-glucanase has 2–5 times the activity of the fungal ones. No evidence for synergic or competitive effects between bacterial and fungal β-glucanases have been found.     

Optimisation of drying conditions for the extraction of β‐carotene,phenolic and ascorbic acid content from yellow‐fleshed sweet potato using response surface methodology

The objective of this study was to optimise drying conditions for the extractions of β‐carotene, phenolic and ascorbic content from yellow‐fleshed sweet potato using response surface methodology. A face‐centred cubic was used to investigate the effects of three independent variables namely drying temperature 55–65 °C, citric acid concentration 1–3%w/v and soaking time 1–3 min. The optimal conditions for parameters were 55–62 °C, citric acid concentration 1.08–2.19% and soaking time 1.53–2.00 min. Under the above mentioned conditions, the experimental β‐carotene content was 14.61 mg g^?1, total phenolic and ascorbic acid content were 4.0 and 17.53 mg g^?1, respectively, which were close to the predicted values. Therefore, the results showed that optimise conditions could be used to enhance the antioxidant activities of functional foods.     

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.     

Purification and physicochemical characterization of ovine β‐lactoglobulin and α‐lactalbumin

Ovine whey proteins were fractionated and studied by using different analytical techniques. Anion‐exchange chromatography and reversed‐phase high‐performance liquid chromatography (HPLC) showed the presence of two fractions of β‐lactoglobulin but only one of α‐lactalbumin. Gel permeation and sodium dodecyl sulfate (SDS)‐polyacrylamide gel electrophoresis allowed the calculation of the apparent molecular mass of each component, while HPLC coupled to electrospray ionisation‐mass spectrometry (ESI‐MS) technique, giving the exact molecular masses, demonstrated the presence of two variants A and B of ovine β‐lactoglobulin. Amino acid compositions of the two variants of β‐lactoglobulin differed only in their His and Tyr contents. Circular dichroism spectroscopy profiles showed pH conformation changes of each component. The thermograms of the different whey protein components showed a higher heat resistance of β‐lactoglobulin A compared to β‐lactoglobulin B at pH 2, and indicated high instability of ovine α‐lactalbumin at this pH.     

Enzymatic Properties of β‐1,3‐Glucanase from Streptomyces sp Mo.

Streptomyces sp Mo endo‐β‐1,3‐glucanase was found to have hydrolyzing activity toward curdlan and released laminarioligosaccharides selectively. The molecular weight was estimated to be 36000 Da and its N‐terminal amino acid sequence was VTPPDISVTN. The optimal pH was 6 and the enzyme was found to be stable from pH 5 to 8. The optimal temperature was 60 °C and the activity was stable below 50 °C. The enzyme hydrolyzed selectively curdlan containing only β‐1,3 linkages. The enzyme had 89% relative activity toward Laminaria digitata laminarin, which contains a small amount of β‐1,6 linkages compared with curdlan, while Eisenia bicyclis laminarin with a higher amount of β‐1,6‐linkages, was not hydrolyzed. Mo enzyme adsorbed completely on curdlan powder. The enzymatic hydrolysis of curdlan powder resulted in the accumulation of laminaribiose (yield 81.7%). Trisaccharide was inevitably released from the hydrolysis of laminarioligosaccharides with 5 to 7 degrees of polymerization (DP). Although the enzyme cleaved off disaccharide (DP 2) from tetrasaccharide (DP 4), the reaction rate was lower than those of DP 5 to 7. The results indicated that the active site of Mo endo‐β‐1,3‐glucanase can efficiently recognize glucosyl residue chain of greater than DP 5 and hydrolyzes the β‐1,3 linkage between the 3rd and 4th glucosyl residue.     

Precipitation of β-carotene microparticles from SEDS technique using supercritical CO2

This work investigates the application of the Solution-Enhanced Dispersion by supercritical fluids technique for the precipitation of β-carotene. The effect of pressure (8.0–12.0 MPa), temperature (293–313 K) anti-solvent flow rate (20–40 mL/min), solution flow rate (1–4 mL/min) and concentration of β-carotene in the dichloromethane solution (4 and 8 mg/mL) on the precipitation yield, particle morphology and particle size and size distribution was examined. Precipitated powders presented mean particle size varying from 3.2 μm to 96.8 μm with morphology of β-carotene microparticles changing from plate-like to leaf-like particles. The statistical analysis of the experimental results revealed that pressure, organic solution concentration and CO₂ flow rate had a significant effect on particle size. The precipitation yield was observed to be within the range of 71–94% and was statistically influenced by system temperature and pressure, and anti-solvent flow rate.     

Impact of α‐amylase and maltodextrin on physicochemical,functional and antioxidant capacity of spray‐dried purple sweet potato flour

BACKGROUND: Purple sweet potato flour could be used to enhance food products through colour, flavour and nutrients. Purple sweet potato flour has not yet been prepared with maltodextrin and amylase treatment using spray drying. Thus, the investigation was to evaluate the effect of various levels of maltodextrin (30 and 50 g kg^?1 w/v), amylase (3 and 7 g kg^?1 puree) and combined with maltodextrin and amylase on the physicochemical, functional and antioxidant capacity of spray dried purple sweet potato flours. RESULTS: Amylase and amylase with maltodextrin‐treated flours had a higher anthocyanin and total phenolic content than the control and maltodextrin‐treated flours. However, the antioxidant capacity was higher in the control and maltodextrin‐treated flours compared to the amylase and amylase with maltodextrin‐treated flours. The control had a higher water absorption index and lower water solubility index compared to the maltodextrin and combined with amylase and maltodextrin‐treated flours. On the other hand, maltodextrin increased whereas α‐amylase decreased the glass transition temperature. With respect to morphology, the particles of amylase‐treated flours were smaller than the control and maltodextrin‐treated flours. CONCLUSION: The results showed that good quality flour could be prepared by combining 30 g kg^?1 maltodextrin and 7 g kg^?1 amylase treatment. Copyright © 2009 Society of Chemical Industry     

SOME BARLEY GRAIN AND GREEN MALT PROPERTIES AND THEIR INFLUENCE ON MALT HOT-WATER EXTRACT: I. β-GLUCAN, β-GLUCAN SOLUBILASE AND ENDO-β-GLUCANASE

A study has been made of the variation between varieties in some properties of barley and malt and how this variation relates to malt hot water extract (HWE). The development of enzyme activity along the grain during germination was investigated. In this first paper we have examined β-glucan-related characters and found significant varietal variation in maximum enzyme activities and in the activities in different sections of grain during germination. Varietal variation was greater than environmental variation for each character. The fraction of β-glucan soluble in acid was the character most highly correlated with HWE.     

Effects of Processing on the Reduction of β-ODAP (β-N-Oxalyl-L-2,3-diaminopropionic acid) and Anti-Nutrients of Khesari Dhal,Lathyrus sativus

Effects of different processing techniques on the neurotoxin, β-ODAP (β- N -oxalyl-L-2,3-diaminopropionic acid), and the anti-nutritional compounds (phytate, polyphenols, trypsin and amylase inhibitors, and lectins) within four lines of Lathyrus sativus (high-, medium- and low-ODAP, and so-called ODAP-free) were investigated. Soaking of seeds in various media reduced the contents of these compounds to a varying and significant extent; losses were higher in freshly boiled water, alkaline and tamarind solutions than after soaking in drinking water. The highest losses in boiled water (65–70%) were observed for β-ODAP, followed by trypsin inhibitors (42–48%) and polyphenols (30–37%). Ordinary cooking and pressure cooking of pre-soaked seeds were found to be most effective in reducing the levels of all the natural toxicants examined, whilst fermentation and germination were more effective in destroying both of the enzyme inhibitors (amylase inhibitors by 69–71%; trypsin inhibitors by 65–66%) than either phytates or polyphenols. Lectins were not affected by most of these processes except by pressure cooking and fermentation. Dehusking of pre-soaked seeds significantly reduced β-ODAP levels, but this reduction was lower for the anti-nutrients. These findings and the high water solubility suggest that a simple and effective means of detoxifying Lathyrus by removing this neurotoxic amino acid may be practicable.     

The Formation of β‐Damascenone in Sweet Potato Shochu

The formation of β‐damascenone during shochu manufacture was investigated by quantifying β‐damascenone at each stage of manufacturing. Steamed sweet potato has a low level of free β‐damascenone (0.02–0.1 μg/g). During fermentation, β‐damascenone was produced in small quantities that were degraded by yeast. Thus, the second mash accumulates little free β‐damascenone (approximately 17 μg/L). The concentration profile in the fractionated distillate showed that β‐damascenone was produced during heating. Most β‐damascenone in shochu was formed during distillation, not during steam heating and fermentation. It is suggested that the level of β‐damascenone in shochu could be increased by reducing the pH of the second mash and prolonging the distillation period. Sweet potato cultivars differed in total free and hydrolyzed β‐damascenone content and there was a strong association between each cultivar and its shochu β‐damascenone content. The selection of the sweet potato cultivar is important for determining the quantity of β‐damascenone in a shochu brew.     

Glycoalkaloids in potato tubers: the effect of variety and drought stress on the α‐solanine and α‐chaconine contents of potatoes

Six varieties of Solanum tuberosum L potato grown in the Bolivian highlands under drought stress, with and without irrigation, were analysed for their content of glycoalkaloids (GAs). The plant material consisted of three drought‐tolerant varieties from a local breeding programme (PROINPA), Potosina, Chapaquita and Pampeña, and three control cultivated varieties, Malcacho, Sani Imilla and Desiree, either susceptible or relatively tolerant to drought. α‐Solanine and α‐chaconine were quantified in both the peel and flesh of the tubers. A significant increase in GA concentration (α‐solanine + α‐chaconine) was observed under drought stress conditions in most varieties; average concentration increases of 43 and 50% were registered in the improved and control cultivars respectively. In all tested cultivars, however, the GA concentration remained lower than the recommended food safety level (200 mg kg⁻¹ fresh tubers). It ranged from 52.4 to 100 mg kg⁻¹ fresh tubers in the improved cultivars and from 55.6 to 122.3 mg kg⁻¹ fresh tubers in the controls. In the improved and control varieties the α‐solanine content averaged 42.6 and 35.4% of the total potato GAs respectively and was not significantly affected by drought stress, except in Desiree. In all conditions the peel contained the greatest proportion of total GAs. The hybrid variety Pampeña (new drought‐tolerant variety) contained the lowest amounts of GAs, which were lower than those of the control varieties, with and without irrigation. © 2000 Society of Chemical Industry     

THE DEGRADATION OF β-GLUCAN DURING MALTING AND MASHING: THE ROLE OF β-GLUCANASE

Significant β-glucanolysis takes place during mashing and is catalysed by a β-glucanase which is specific to mixed-linkage β-glucans. The enzyme develops during the germination of barley, but is rapidly and extensively destroyed in kilning. Partially-purified preparations of β-glucanase are protected from denaturation by heat if their solutions are adjusted to pH 4 or if bovine serum albumin is added. However the most effective stabiliser of the enzyme is reduced glutathione. Oligosaccharides containing three and four glucosyl units are produced by the action of β-glucanase and they are further converted during malting and mashing by a different enzyme(s) to disaccharides and glucose.     

Release of β-casomorphins 5 and 7 during simulated gastro-intestinal digestion of bovine β-casein variants and milk-based infant formulas

The release of β-casomorphin-5 (BCM5) and β-casomorphin-7 (BCM7) was investigated during simulated gastro-intestinal digestion (SGID) of bovine β-casein variants (n = 3), commercial milk-based infant formulas (n = 6) and experimental infant formulas (n = 3). SGID included pepsin digestion at pH 2.0, 3.0 and 4.0 and further hydrolysis with Corolase PP™. β-Casein (β-CN) variants were extracted from raw milks coming from cows of Holstein-Friesian and Jersey breeds. Genomic DNA was isolated from milk and the β-CN genotype was determined by a PCR-based method. Phenotype at protein level was determined by capillary zone electrophoresis in order to ascertain the level of gene expression. Recognition and quantification of BCMs involved HPLC coupled to tandem MS. Regardless of the pH, BCM7 generated from variants A1 and B of β-CN (5–176 mmol/mol casein) the highest amount being released during SGID of form B. As expected, the peptide was not released from variant A2 at any steps of SGID. BCM5 was not formed in hydrolysates irrespective of either the genetic variant or the pH value during SGID. Variants A1, A2 and B of β-CN were present in all the commercial infant formulae (IFs) submitted to SGID. Accordingly, 16–297 nmol BCM7 were released from 800 ml IF, i.e. the daily recommended intake for infant. Industrial indirect-UHT treatments (156 °C × 6–9 s) did not modify release of BCM7 and, during SGID, comparable peptide amounts formed in raw formulation and final heat-treated IFs.     

Effect of Mashing Temperatures and Endo-β-Glucanase on β-Glucan Content of Malt Worts

Similar basal levels of β-D-glucans were released into worts produced at 45°C from enzymically active or inactivated flours of milled malts. In contrast, significantly higher levels of β-D-glucans were found in worts derived from either enzymically active or inactivated malt flours mashed at 65°C. In general, mashing temperature may play a more important role in releasing β-D-glucans during mashing than enzymes described as β-glucan-releasing. In this context, the physical release of β-D-glucan during mashing should be separated from the enzymic release and degradation of β-D-glucan which occur during malting.     

β-gliadin proteins from Maris Widgeon wheat

Four β-gliadins have been isolated from the English wheat, Maris Widgeon by Sephadex SP C25 ion-exchange chromatography of the gliadin mixture followed by G-75 or G-100 gel-filtration of either the native or reduced and alkylated proteins. Amino acid analyses of the proteins indicate similar compositions of β₂- and β₄-gliadins and also of β₃- and β₅-gliadins. Minimal molecular weights from amino acid analysis for all four proteins lie within the range 28000 to 30000.     

Variety and germination time effect on total β‐glucan,water‐insoluble β‐glucan,water‐soluble β‐glucan components and β‐glucanase levels in improved sorghum varieties SK5912, KSV8 and ICSV400 before and after malting and their relationships to wort viscosity

The effects of variety and germination time on β‐glucan components – total β‐glucan (TBG), water insoluble β‐glucan (WIBG) and water soluble β‐glucan (WSBG) and β‐glucanase (BG) levels – before and after malting in improved sorghum varieties SK5912, KSV8 and ICSV400 and their relationships to wort specific viscosity (SV) were studied. This study was part of efforts to aid local malting and brewing industries in the application of sorghum varieties that are abundantly available to reduce costs. At the fifth day of germination, variety ICSV400 had the lowest TBG, WIBG and WSBG levels in its raw and malt samples. Variety SK5912 had the highest TBG, WIBG and WSBG levels in its raw samples, while variety KSV8 had the highest levels of TBG, WIBG and WSBG in its malt samples. Similarly, variety ICSV400 malts developed the highest BG levels, while the KSV8 malts gave the lowest level. The effect of variety, germination time and variety × germination time interaction was significant (p < 0.05) on the TBG, WIBG and BG levels and was not significant on the WSBG levels. Weak and significant correlation of TBG levels with SV (0.25, p < 0.05 for SK5912; 0.24, p < 0.05 for KSV8; and 0.31, p < 0.05 for ICSV400) was observed in all the samples, suggesting that the low β‐glucan levels may not be primarily and solely responsible for any viscosity impediments associated with sorghum worts during run‐off. With improvement in the effective utilization of sorghum, ICSV400 appeared the most suitable variety for malting and brewing in Nigeria.Copyright © 2016 The Institute of Brewing & Distilling     

LEVELS OF ALKALI-SOLUBLE β-D-GLUCANS IN CEREAL GRAINS

Extraction of β-D-glucans (primarily from barley grains) using sodium hydroxide solution, gave similar results to those obtained using hydrazine extraction, suggesting that the alkali is as effective as hydrazine for the extraction of β-D-glucans. Commercial growth conditions in different European countries caused limited shifts in the β-D-glucan levels of malting barley samples. Sorghum and wheat grains contained significantly less β-D-glucans than barley. Potassium bromate solution inhibited initial breakdown of β-D-glucans during the malting of barley grains. The breakdown of β-D-glucan in Sonja barley was much slower than in Golden Promise barley, during malting.