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LWT-Food Science & Technology
Elsevier
LWT-Food Science & Technology

Elsevier

0023-6438

LWT-Food Science & Technology/Journal LWT-Food Science & Technology
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    Effects of different stabilization techniques on the shelf life of cold brew coffee: Chemical composition, flavor profile and microbiological analysis

    Bellumori, MariaAngeloni, GiuliaGuerrini, LorenzoMasella, Piernicola...
    11页
    查看更多>>摘要：Cold brew coffee is a beverage prepared at low temperatures and over long brewing times resulting in particular physicochemical and sensory characteristics. This type of coffee is usually consumed immediately after preparation or after short storage in refrigerated conditions. However, in recent years many commercial coffee vendors started investing in ready-to-drink cold brew coffees packaged for extended storage. These products present the potential problem of microbial and sensorial alteration. In this study we evaluated five different stabilization techniques with the aim to extend the shelf life of the cold brew coffee while preserving its peculiar organoleptic properties, e.g. HPP (High Pressure Processing), microfiltration, UV irradiation, pasteurization and blast chilling process. The effects were investigated over four months, evaluating the caffeine and the chlorogenic acids contents by HPLC-DAD analysis and carrying out anevaluation of selected volatile compounds by HS-SPME-GC-MS. After four months of storage, the samples treated with pasteurization and HPP maintained a stable content of caffeine and chlorogenic acids, guaranteeing also the microbiological safety of the beverage. At the same shelf-time, the pasteurized samples showed an unaltered flavor profile, while a decrease of about 25% of the total content of volatile compounds was registered for the HPP sample.
      原文链接:
    • NSTL
    • Elsevier

    Effect of the rice flour particle size and variety type on water holding capacity and water diffusivity in aqueous dispersions

    Lapcikova, BarboraLapcik, LubomirValenta, TomasMajar, Petr...
    8页
    查看更多>>摘要：The aim of this study was to evaluate water binding capacity of selected varieties of rice flours as prospective processing parameter for manufacturing gluten-free products. Water retention capability was determined by measuring the effective diffusivity coefficient, DSC, water absorption index and water solubility index. It was found that with decreasing particles size of flour the water binding capacity was increasing. This phenomenon was dependent also on the saccharides and proteins content of individual materials. There was measured gelatinization temperature and enthalpy of fusion. It was found to be 2.08 J/g for black and 5.8 J/g for fine rice flour. Effective moisture diffusivities of 6.167 x 10(-10) m(2) s(-1) for black and of 5.030 x 10(-10) m(2) s(-1) for fine rice flours were found. The latter were of the lowest magnitudes from the set of the studied samples, indicating their highest ability to retain water in their microstructure. There was confirmed structural binding of water based on rheological testing.
      原文链接:
    • NSTL
    • Elsevier

    Studies of quality development and major chemical composition of green tea processed from tea with different shoot maturity

    Liang, LuLi, YuhaoYang, TianmingFan, Yunxue...
    9页
    查看更多>>摘要：Apart from geographical difference and processing method, the maturity of fresh tea shoot is an important factor that determines tea quality. However, the quality development and chemical variation of green tea with tea shoot maturity remain unclear. This study aimed to investigate the metabolic consequences of tea shoot maturity on the taste and aroma quality of green tea by metabolite profiling. In terms of taste quality, a concentration-dependent decrease with tea shoot age was observed in gallic acid and caffeine. The levels of catechin, epicatechin, and epigallocatechin increased with tea shoot maturity, whereas those of epicatechin gallate, epigallocatechin gallate, and total catechins decreased. Furthermore, the maximum contents of most amino acids were recorded in green tea processed from one bud with two leaves. In terms of aroma quality, volatile profiles of green tea were analyzed by gas chromatography-mass spectrometry combined with chemometrics. A total of 32 differential volatile organic compounds showing significant differences were identified and divided into Groups I and II, which contribute undesirable flavor and sweet flowery aroma to tea, respectively. The relative abundance of Group I increased with tea shoot maturity whereas that of Group II decreased. These findings can be used in guiding the production of green tea.
      原文链接:
    • NSTL
    • Elsevier

    Antibacterial mechanism and preservation effect of curcumin-based photodynamic extends the shelf life of fresh-cut pears

    Chai, ZhengyuanZhang, FangLiu, BingjieChen, Xuefeng...
    10页
    查看更多>>摘要：Foodborne pathogen is a major threat to human health. In this study, we evaluated the bactericidal efficacy of curcumin-based photodynamic inactivation (PDI) against Listeria monocytogenes, elucidated its underlying bactericidal mechanisms including membrane damage, oxidative stress and protein degradation. Depending on curcumin concentration and illumination duration, the reactive oxygen species (ROS) increased rapidly after PDI treatment, resulting in severe cell membrane damage and protein degradation. Meanwhile, the activity of ROS defense enzymes such as superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) was inhibited significantly (p < 0.05), amplifying the oxidative damage to bacteria. Besides, fresh-cut pears were treated by PDI and then stored at 4 degrees C for 6 d to investigate the changes of color and hardness. The populations of L. monocytogenes on fresh-cut pears were significantly (p < 0.05) reduced by 3.43 log CFU/g after PDI without causing quality deterioration. After storage for 6 d, pears treated by PDI remained higher (p < 0.05) L* (60.91 +/- 4.48) and hardness (51.19 +/- 3.77 N). These results suggested that curcumin-based PDI to inactivate foodborne pathogens could be applied as a potential food safety technology.
      原文链接:
    • NSTL
    • Elsevier

    Flavor differences between commercial and traditional soybean paste

    Zhang, XiaoWei, JianpingZhao, ShiyuJia, Hang...
    9页
    查看更多>>摘要：Fermented soybean paste is becoming popular worldwide due to its umami taste and characteristic aroma. To elucidate the relationships between the odorants and the flavor differences of commercial soybean paste (CSP) and traditional soybean paste (TSP), 49 samples (13 CSP, 36 TSP) were collected and evaluated in this research. The aroma-active compounds of CSP and TSP samples were analyzed by electronic nose, gas chromatography-olfactometry-mass spectrometry combined with aroma extract dilution analysis, and the key aroma compounds were identified by calculation of the detection rates and odor activity values. Following characterization, 23 and 19 odorants were identified as key aroma compounds contributing to flavor differences in CSP and TSP samples, respectively. Significant differences were observed for the acids, alcohols, aldehydes, terpenes, and sulfur-containing compounds. The results showed that the flavor differences of the samples were more resulted from the concentrations of the key aroma compounds rather than their compositions and those differences mainly came from the long maturation period of TSP samples and heating process of CSP samples. Further, orthogonal partial least squares discrimination analysis revealed that the key aroma compounds identified in this research could explain the flavor differences of commercial and traditional soybean pastes.
      原文链接:
    • NSTL
    • Elsevier

    Protein fortification of wheat bread using dry fractionated chickpea protein-enriched fraction or its sourdough

    Xing, QinhuiKyriakopoulou, KonstantinaZhang, LuBoom, Remko M....
    9页
    查看更多>>摘要：Chickpea protein-enriched ingredients were prepared by combining dry milling, air classification, and optionally solid-state fermentation. The fermentation was carried out with the autochthonous LAB strain Pediococcus acidilactici to reduce the level of antinutritional factors. A protein-enriched chickpea fraction and its sourdough were used to partially replace wheat flour with 20%-30% w/w in wheat bread. The protein content of bread increased by 38.5% on dry basis with a 30% w/w replacement. As the substitution level increased from 0% to 20% and 30%, a longer dough mixing time was required, the specific volume of the bread decreased, and the crumb structure became denser. The levels of raffinose, stachyose, and verbascose in the sourdough bread were reduced by 75.4%, 97.6%, and 90.0% compared to the unfermented bread, respectively. With sourdough addition the crust showed less browning and exhibited a better microbiological stability compared to that of the other breads.
      原文链接:
    • NSTL
    • Elsevier

    Physiochemical, microbiological and flavor characteristics of traditional Chinese fermented food Kaili Red Sour Soup

    Li, DafeiDuan, FeixiaTian, QimingZhong, Dingjiang...
    9页
    查看更多>>摘要：Kaili Red Sour Soup (RSS) is a traditional fermented vegetable sauce made from red chili pepper and tomato, through special two-round anaerobic fermentations in southwest China, however, its physicochemical, microbial and flavor characteristics remain unclear. The pH value, total titratable acidity, amino acid nitrogen and nitrite of repined Kaili RSS were determined to be 3.26, 27.34 g/kg, 3.04 mg/kg and 3.04 mg/kg, respectively. HPLC spectra showed 7 organic acids in RSS, and lactic acid (24.71 g/kg) and acetic acid (6.41 g/kg) mainly contribute to sour tastes. 15 Amino acids were found in RSS, and alanine (73.19 mg/100g) directly contributed to RSS's umami. The results of GC-MS illustrated totally 76 volatile organic compounds including alcohols, acids, esters, hydrocarbons, phenols, aldehydes, ketone and heterocycles, while alcohols (41.14%), acids (17.92%) and esters (29.37%) were dominant. Colony count number assay and rDNA amplicon-based high-throughput sequencing revealed 66 bacteria genera and 139 fungi during RSS fermentation, and Lactobacillus accounted for 94.81% in the first-round fermentation, while Pichia (49.71%), Dekkera (30.00%) and Saccharomyces (14.96%) were the dominant fungi in second-round fermentation. The Pearson correlation coefficient suggested that L. acetotolerans, Pichia, Dekkera and Saccharomyces could contribute mainly to the special flavors of Kaili RSS.
      原文链接:
    • NSTL
    • Elsevier

    Development of functional gelatin-based composite films incorporating oil-in-water lavender essential oil nano-emulsions: Effects on physicochemical properties and cherry tomatoes preservation

    Sun, XinyuWang, JiaoZhang, HuiDong, Mengna...
    9页
    查看更多>>摘要：This study presented a facile approach for fabricating oil-in-water lavender essential oil nano-emulsions (LEONs) with excellent antibacterial and antioxidant activities. Besides, LEONs with different LEO content (50, 100, 200 and 300 mu L/10 mL) were incorporated to the matrix of gelatin (GL) for preparing multifunctional GL-LEONs films, which exhibited strong antibacterial properties against Staphylococcus aureus, Escherichia coli and Listeria monocytogenes, as well as excellent antioxidant activities. Additionally, the GL-LEONs films exhibited sustained release characteristics, excellent UV light barrier performances and good heat-sealing properties. Furthermore, the GL-LEONs films were applied to the preservation of cherry tomatoes at 25 +/- 2 degrees C for 7 days. The results revealed that the deterioration of cherry tomatoes packaged with the GL-LEONs films was suppressed during storage, which mainly reflected in reducing weight loss, delaying the degradation of titratable acids and phenolic components, and inhibiting the growth of microorganisms.
      原文链接:
    • NSTL
    • Elsevier

    Effect of digestion and thermal processing on the stability of microbial cell-aflatoxin B1 complex

    Balsini, Mohammad SohrabiDovom, Mohammad Reza EdalatianKadkhodaee, RassoulNajafi, Mohammad Bagher Habibi...
    7页
    查看更多>>摘要：This study investigates the removal of aflatoxin B1 by viable and heat treated cells of Saccharomyces cerevisiae (PTCC 5052) and Lactobacillus rhamnosus GG (ATCC 53103) in a model system as a function of time and salt concentration. Moreover, the stability of microbial cell-aflatoxin B1 complex was evaluated at elevated temperature, high shear stress as well as under simulated digestive conditions. The rate of aflatoxin B1 adsorption was found to be significantly different for viable and heat treated cells. Heat inactivation of L. rhamnosus GG and S. cerevisiae dramatically increased the rate of toxin adsorption to 97.74% and 92.34%, respectively. Desorption of aflatoxin B1 from L. rhamnosus GG was approximately 3 times greater than viable S. cerevisiae and nearly1.5 times higher than heat treated cells. The maximum desorption of aflatoxin B1 from complexes occurred after 3 h incubation in simulated intestinal fluid. Shear stress and simulated saliva had no impact on the breakage of cell-aflatoxin B1 complex. The complexes formed by heat treated cells exhibited high stability against thermal treatment, whilst those generated by viable strains experienced toxin release during heating, which was much higher for S. cerevisiae (%4.68) than L. rhamnosus GG (%0.99).
      原文链接:
    • NSTL
    • Elsevier

    Effect of radio frequency tempering on the color of frozen tilapia fillets

    Jiang, JiweiWang, HongliGuo, XueqianWang, Xichang...
    7页
    查看更多>>摘要：Radio frequency (RF) processing has been widely used for thawing and tempering of frozen products for further processing and consumption. RF tempering could improve the color and other qualities compared with traditional methods, but the specific mechanism to ensure the color is not clear. Effect of different RF treatments on the color of frozen tilapia fillet was to investigate in this study. The color of tempered tilapia fillets under different RF conditions (based on power (300, 600, 900 W) and electrode gap (10, 12, 14 cm)) and the myoglobin oxidation, lipid oxidation, and moisture migration and other influencing factors on color were determined. Relationships between relative impact indicators and color attributes were investigated by multivariate analysis (visual network analysis). The results showed that hue angle and whiteness between 600 W and other power had significant differences under the electrode gap of 10 cm and 14 cm. The difference in color attributes under different RF tempering conditions had a relatively strong correlation with pH, migration of bound water to immobilized water, content of immobilized water, and drip loss during RF tempering. Besides, the difference of color attributes weakly correlated with myoglobin oxidation and lipid oxidation during RF tempering.
      原文链接:
    • NSTL
    • Elsevier