Characteristic aroma compounds of cooked and fermented soybean (Chungkook‐Jang) inoculated with various Bacilli

BACKGROUND: For selecting Chungkook‐jang products with a less undesirable odour, the volatile compounds that affect the overall consumer acceptance of Chungkook‐jang products were analysed. The volatile compounds of Chungkook‐jang were extracted by using solid phase microextraction and direct solvent extraction and were detected by using gas chromatography‐olfactometry. The results were represented as the mean of the log₃ flavour dilution factors; principal component analysis was used to determine the effective components. RESULTS: Fifteen and 14 volatile compounds were detected in the extracts using solid phase microextraction and direct solvent extraction, respectively. The Bacillus species 2‐M1L, which has the most overall acceptance, might have a nutty initial top note and nutty and cheesy long‐lasting note aromas. In correlation analysis between the characteristic aromas and the overall acceptance, trimethyl pyrazine (nutty, pungent), butanoic acid (cheesy, butyric), and methyl pyrazine (burnt, roasted) were positively correlated with overall acceptance. In contrast, 3‐hydroxy‐2‐butanone (buttery, fatty) and 2,3‐butanediol (chemical, fatty) were negatively correlated with overall acceptance. CONCLUSION: Consumers might prefer Chungkook‐jang that has a more nutty and cheesy flavour and a less fatty one. Copyright © 2012 Society of Chemical Industry     

Isolation and characterization of pepsin‐solubilized collagen from the integument of sea cucumber (Stichopus vastus)

BACKGROUND: Sea cucumber (Stichopus vastus) is considered an underutilized resource, since only its stomach and intestines are eaten raw as salad in a few countries and the remaining parts, especially the integument rich in collagen, is discarded. Hence a valuable by‐product having potential nutraceutical and pharmaceutical applications is wasted. In the present investigation, pepsin‐solubilized collagen (PSC) from the integument of S. vastus was isolated, purified and characterized. RESULTS: Sodium dodecyl sulfate–polyacrylamide gel electrophoretic analysis showed that the purified collagen was of type I, consisting of three α1 chains of approximately 122 kDa each. The peptide map of PSC digested by V8 protease was different from that of calf skin type I collagen. Fourier transform infrared spectroscopy revealed that the triple helical structure was well preserved in isolated collagen. The denaturation temperature of PSC was 21.23 °C and showed good gel‐forming capability at pH 6.5 and 300 mmol L^?1 NaCl. CONCLUSION: It is inferred that the collagen isolated from S. vastus integument has potential for use as an alternative to land‐based mammalian collagen in food, nutraceuticals and pharmaceutical industries. © 2012 Society of Chemical Industry     

Isolation of a free radical‐scavenging antioxidant from water spinach (Ipomoea aquatica Forsk)

Ipomoea aquatica Forsk, a green leafy vegetable that is a rich source of vitamins and amino acids with many health benefits, has been explored for the isolation and identification of its bioactive compounds. Activity‐guided repeated fractionation of a methanol extract on a silica gel column followed by an XAD column yielded a compound that exhibited antioxidant activity with an EC₅₀ value of 83 ± 1.02 µg ml^?1 reaction mixture. It also showed very strong lipid peroxidation‐inhibitory activity in a liposome model system with an EC₅₀ value of 72.2 ± 0.9 µg ml^?1. However, it showed negligible metal‐chelating activity. Based on UV, 2D nuclear magnetic resonance and gas chromatography/mass spectrometry studies, the compound was tentatively identified to be 7‐O‐β‐D ‐glucopyranosyl‐dihydroquercetin‐3‐O‐α‐D ‐glucopyranoside. This is the first report on the antioxidant properties of I aquatica leaf extracts. Copyright © 2005 Society of Chemical Industry     

Microwave‐accelerated Synthesis and Characterization of Potato Starch‐g‐poly(acrylamide)

Using a very low concentration of potassium persulfate as initiator, acrylamide could be efficiently grafted onto potato starch under microwave irradiation and for the grafting O₂ removal from the reaction vessel was not required. Under optimal conditions, grafting and efficiency observed were 160% and 89%, respectively. Grafted starch was characterized by using Fourier transform infrared spectroscopy (FTIR), X‐ray diffraction (XRD) and thermogravimetric analysis (TGA). It was observed that the microwave irradiation could significantly accelerate the synthesis of starch‐graft‐poly(acrylamide), because under identical conditions no grafting was observed in a conventional procedure. Viscosity, shear stability and water/saline solution retention of the microwave‐synthesized grafted starch were studied and compared with that of the parent starch.     

Determination of S‐methyl‐L‐methionine (SMM) from Brassicaceae Family Vegetables and Characterization of the Intestinal Transport of SMM by Caco‐2 Cells

The objectives of the current study were to determine S‐methyl‐L‐methionine (SMM) from various Brassicaceae family vegetables by using validated analytical method and to characterize the intestinal transport mechanism of SMM by the Caco‐2 cells. The SMM is well known to provide therapeutic activity in peptic ulcers. The amount of SMM from various Brassicaceae family vegetables ranged from 89.08 ± 1.68 μg/g to 535.98 ± 4.85 μg/g of dry weight by using validated ultra‐performance liquid chromatography‐electrospray ionization‐mass spectrometry method. For elucidating intestinal transport mechanism, the cells were incubated with or without transport inhibitors, energy source, or a metabolic inhibitor. Phloridzin and verapamil as inhibitors of sodium glucose transport protein (SGLT1) and P‐glycoprotein, respectively, were not responsible for cellular uptake of SMM. Glucose and sodium azide were not affected by the cellular accumulation of SMM. The efflux ratio of SMM was 0.26, implying that it is not effluxed through Caco‐2 cells. The apparent coefficient permeability (P _app) of SMM was 4.69 × 10^?5 cm/s, indicating that it will show good oral absorption in in vivo .     

Isolation and Characterization of Chitinase‐Producing Bacillus and Paenibacillus Strains from Salted and Fermented Shrimp,Acetes japonicus

Chitinases catalyze the conversion of chitin and are produced by a wide range of bacteria. The biological applications of these enzymes have been exploited in food and pharmaceutical industries. We isolated 2 halophilic chitinase‐producing novel strains of bacteria—SCH‐1 and SCH‐2 from Saeu‐jeot, a traditional Korean salted and fermented food made with shrimp (Acetes japonicus). The isolated strains‐ SCH‐1 and SCH‐2 were Gram‐positive, rod‐shaped, endospore‐forming facultative anaerobes, with strain SCH‐2 showing peritrichous flagella. Molecular characterization of the 16S rRNA gene identified the strains SCH‐1 and SCH‐2 as Bacillus sp. and Paenibacillus sp. respectively. Basic Local Alignment Search Tool and subsequent phylogenetic analysis of strain SCH‐1 showed an identity of 97.83% with Bacillus cereus ATCC 14579 (NR_074540), whereas strain SCH‐2 showed an identity of 99.16% with Paenibacillus lautus JCM 9073 (NR_040882). Furthermore, the SCH‐1 strain could use glucose, N‐acetyl glucosamine, esculin, and maltose as carbon source substrates. Cellular fatty acid analysis showed that iso‐C_15:0 and anteiso‐C_15:0 are the major acids in strain SCH‐1 and SCH‐2, respectively. The SCH‐1 strain showed a higher chitinase activity at 15.71 unit/mg protein compared with SCH‐2 strain. Chitinase isozymes of Bacillus sp. SCH‐1was expressed as 2 bands having sizes of 41 and 50 kDa, and as 4 bands with sizes of 30, 37, 45.7, and 50 kDa in Paenibacillus sp. SCH‐2. The rich chitinase activity with the isozyme profiles of the isolated Bacillus and Paenibacillus strains provide advancement in the study of fermentation and may play putative functions in the chitin bioconversion of sea crustacean foods.     

Isolation and characterization of Candida kefyr orotidine‐5′‐phosphate decarboxylase (URA3) gene

Candida kefyr is a common yeast species that can be found in fermented milk and cheeses. As a first step to developing a gene transfer system for C. kefyr, the orotidine‐5′‐phosphate decarboxylase (URA3) gene was cloned, using degenerate PCR and genome walking. The uninterrupted open reading frame of the C. kefyr URA3 gene spans 801 bp, corresponding to 267 amino acid residues. The functionality of the gene was confirmed by complementation of ura3 auxotrophs of C. albicans and Saccharomyces cerevisiae. Phylogenetic analysis of the deduced amino acid sequence indicated that it shares a high degree of homology with other Candida URA3 homologues. The GenBank Accession No. of the C. kefyr URA3 gene is FJ914763. Copyright © 2009 John Wiley & Sons, Ltd.     

Isolation and Detection of Extended Spectrum β‐Lactamase (ESBL)‐Producing Enterobacteriaceae from Meat using Chromogenic Agars and Isothermal Loop‐Mediated Amplification (LAMP) Assays

The aim of this work was to develop a molecular method using loop‐mediated isothermal amplification (LAMP) for detection of extended spectrum β‐lactamase (ESBL)‐producing Enterobacteriaceae from meat, and to compare it with different isolation agars and microarrays. LAMP assays were developed for CTX‐M groups 1, 2, and 9 and OXA‐10‐like genes. Chicken, lamb, beef, pork, and turkey samples were spiked with 10, 100, and 1,000 cfu/gram using 8 strains of ESBL‐producing Enterobacteriaceae (CTX‐M sequence types 1, 2, 3, 14, 15, OXA‐11, SHV‐2, TEM‐52) +/– a mix of competitor organisms. Samples were enriched overnight in buffered peptone water (BPW) +/– antibacterials before plating to CHROMagar CTX, OXOID ESBL Brilliance agar, and MacConkey agar with 1 mg/L cefotaxime. Selected BPW broths were also tested using LAMP assays, microarrays and using cefpodoxime discs on agar. For isolation/detection of ESBL producers from beef, pork, lamb, and turkey spiked with 10 or 100 cfu/gram ESBL (natural flora only), all agars and the LAMP assays showed 100% sensitivity and specificity for ESBL spike strains. For chicken samples, both LAMP and chromogenic agars showed improved sensitivity and specificity for isolation of ESBLs compared with MacConkey agar, particularly with competitor bacteria added. In comparison, the cefpodoxime disc method and microarray showed reduced sensitivity.     

Bioconversion of agro‐industrial by‐products to lactic acid using Lactobacillus sakei and two Pediococcus spp. strains

The aim of this study was to evaluate the bioconversion efficiency of rich in cellulose agro‐industrial by‐products such as wheat bran (WB), spent distiller's grain with solids (DGS), brewer's spent grain (BSG) and lupin (Lupinus angustifolius L.) wholemeal fraction (LF) to lactic acid (LA) using acid tolerant lactic acid bacteria (LAB) strains Lactobacillus sakei KTU05‐06, Pediococcus acidilactici KTU05‐7 and P. pentosaceus KTU05‐9. Carbohydrase preparation Depol^? 692L was used for the hydrolysis of non‐starch polysaccharides. Analysed raw materials were suitable substrates for LAB propagation and L‐lactic acid production. The lowest pH (3.6) was found in LF medium after 48 h fermentation with P. acidilactici and P. pentosaceus strains. The lowest pH (3.86) was measured in WB fermented with L. sakei, and in DGS and BSG (pH 3.8 and 3.9 respectively) fermented with P. acidilactici. The highest endoxylanase activity was excreted by the P. acidilactici and P. pentosaceus (84 and 69 XU g^?1 respectively), and the highest α‐amylase activity was of L. sakei (255.6 AU g^?1) after 24 h incubation in WB medium. The L‐lactic acid concentration of 86.11 g kg^?1 was reached after the bioconversion of hydrolysed WB in combination with 48 h fermentation by P. pentosaceus KTU05‐9 strain. LA contents between 222 and 282 mg kg^?1 was produced from lupin processing residues via fermentation using P. acidilactici and P. pentosaceus KTU05‐9 strains. The major challenge within the presented study is the viability of tested LAB in cereal waste media and effective LA production at a low pH (3.6–3.8).     

Characterization of the Saccharomyces bayanus‐type AGT1 transporter of lager yeast

Transport of maltose and maltotriose into the yeast cell is thought to be rate‐limiting in the utilization of these sugars. The maltose and maltotriose transporters Malx1, Agt1, Mtt1 and Mphx are present in different combinations in brewer's yeast strains, conferring different maltose and maltotriose transport characteristics on the strains. A new putative maltose/maltotriose transporter ORF was identified during whole genome sequencing of the lager strain WS34/70 (Y. Nakao et al., DNA Res., 2009, 16, 115–129). Sequence comparisons suggested that this putative α‐glucoside transporter might be a Saccharomyces bayanus counterpart of the Agt1 (Saccharomyces cerevisiae type) transporter. In the present work, the transporter coded by a SbAGT1 gene from a lager strain, A15 (and with the same sequence as the corresponding gene in WS34/70) was characterized. It is shown that this SbAGT1 encodes a functional α‐glucoside transporter with a wide‐substrate range, including maltose and maltotriose. Trehalose, α‐methylglucoside and sucrose were inhibitors, suggesting they are also substrates. The SbAgt1 transporter had similar affinities for maltose and maltotriose (17 ± 7 and 22 ± 2 m m , respectively) and a higher V_max for maltose than maltotriose (21 ± 7 and 12 ± 2 µmol min^?1 g dry yeast^?1, respectively). Copyright © 2012 The Institute of Brewing & Distilling     

Response Surface Methodology for the Optimization and Characterization of Cassava Starch‐graft‐Poly(acrylamide)

Response surface methodology (RSM) was employed for the synthesis of cassava starch‐graft‐poly(acrylamide) using ceric ammonium nitrate as free radical initiator. Concentration of acrylamide, concentration of ceric ammonium nitrate, reaction temperature and duration of reaction were optimized using a 4‐factor 3‐level Box‐Behnken design. The dependent variables were percentage grafting (%G) and grafting efficiency (GE). Second order polynomial relationships were obtained for %G and GE, which explained the main, quadratic and interaction effects of factors. The highest%G and GE obtained were 174.8% and 90.7%, respectively. The optimum values of parameters predicted through RSM were 20 g acrylamide/10 g dry starch, 3.3 g/L ceric ammonium nitrate, 180 min reaction duration and 45ºC temperature with a %G of 190.0. For GE, the predicted levels of factors for the optimum value of 90.8% were 17.5 g acrylamide/10 g dry starch, 4.1 g/L ceric ammonium nitrate, 180 min reaction duration and 55ºC temperature. The graft reaction was confirmed by FTIR analysis, where the absorption bands corresponding to the C=O stretching and N‐H bending of the –CONH₂ group were observed. Scanning electron microscopic studies on grafted starches revealed that the granular structure of the starch was affected by the reaction. X‐ray diffraction analysis showed that the crystallinity of starch was decreased as a result of grafting and the reduction was higher for the grafted starches with higher percentage grafting.     

Characterization of Aroma Compounds in Chinese Bayberry (Myrica rubra Sieb. et Zucc.) by Gas Chromatography Mass Spectrometry (GC‐MS) and Olfactometry (GC‐O)

Abstract: The aroma‐active compounds in Chinese bayberry were identified using gas chromatography‐olfactometry (GC‐O) and GC‐mass spectrometry techniques. The volatile compounds were extracted using Liquid–liquid extraction, solvent‐assisted flavor evaporation and headspace solid‐phase microextraction (HS‐SPME), respectively. On the basis of odor intensity, the most important aroma compounds in Chinese bayberry samples were caryophyllene, menthol, 4‐terpineol, linalool oxide, linalool, benzyl alcohol, α‐methylbenzyl alcohol, β‐phenylethanol, 3‐methylbutanoic acid and acetic acid, and so on. Moreover, HS‐SPME technique was employed to investigate the aroma compounds among immature and mature waxberry fruits. The results showed that terpenes (for example, β‐caryophyllene) was predominant and its concentration represented over 89.9% of the overall compounds, and alcohols, aldehydes, ketones, esters, acids, and others were typically present in lesser amounts. Finally, principal component analysis revealed that there was also significant difference between immature and mature waxberry fruits     

Ultrasound‐assisted extraction of polyphenols from potato peels: profiling and kinetic modelling

Ultrasound‐assisted extraction (UAE) at 33 and 42 kHz has been investigated in the extraction of polyphenols from peels of two potato varieties, cream‐skinned Lady Claire (LC) and pink‐skinned Lady Rosetta (LR), commonly used in snack food production. Extraction efficacy between the UAE‐untreated (control) and the UAE‐treated extracts was assessed on the total phenolic content and antioxidant capacities (DPPH and FRAP). Application of UAE showed significantly higher recovery of phenolic compounds compared to solid–liquid extraction process alone. Lower ultrasonic frequency (33 kHz) was more effective in recovering polyphenols compared to 42 kHz ultrasonic treatment. The liquid chromatography‐tandem mass spectrometry revealed that chlorogenic acid and caffeic acid were the most prevalent phenolics in LR peels, whereas caffeic acid was dominant in LC peels. Peleg's equation showed a good correlation (R² > 0.92) between the experimental values and the predicted values on the kinetics of UAE of phenolic compounds.