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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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    Preparation of porous starch by alpha-amylase-catalyzed hydrolysis under a moderate electric field

    Li, DandanTao, YangShi, YaningWu, Zhengzong...
    8页
    查看更多>>摘要：Enzymatically-catalytic conversion of starch-based industrial waste into porous materials was enhanced by a moderate electric field (MEF). Changes in the hydrolysis rate, a-amylase activity and starch structure during MEF treatment (0-20 V, 0-400 Hz, room temperature and 0-2 h) were monitored and the hydrolyzed products were characterized by scanning electron microscopy, X-ray diffraction and water/oil adsorption analyses. The results showed that MEF enhanced enzymatic hydrolysis mainly by destroying starch structure, rather than by altering a-amylase activity. The average number of pores of hydrolyzed starch increased when voltage increased from 2 to 15 V, but a further increase of voltage caused the gelatinization of starch, thus making it unfavorable for the preparation of porous materials. The crystallinity of electrically-treated porous starches was decreased by 2.87-5.06%. The water and oil adsorption capacity of the porous starches was much higher than that of their native counterpart. Overall, this study extends the applications of electric field-based techniques in an enzymatic modification of biomaterials.
      原文链接:
    • NSTL
    • Elsevier

    Noncovalent interaction of cyanidin-3-O-glucoside with whey protein isolate and beta-lactoglobulin: Focus on fluorescence quenching and antioxidant properties

    Meng, YueyueHao, LinlinTan, YingYang, Yuzhuo...
    8页
    查看更多>>摘要：Cyanidin-3-O-glucoside (C3G) is the major anthocyanin which has a variety of biological activities. Whey protein isolate (WPI) is an essential protein of milk with beta-lactoglobulin (beta-LG) as the most abundant component. In this study, noncovalent interactions of C3G with WPI and beta-LG and antioxidant properties of their complexes were investigated. Analysis of the fluorescence data showed that C3G-induced quenching was not controlled by dynamic collision, instead is due to the formation of a complex, therefore the interactions between C3G and dairy proteins was typical static quenching. For the C3G-beta-LG complex, the binding constant and number of binding sites were determined, and hydrophobic interactions played the major role. Three concentrations of C3G displayed a remarkable synergism of radical scavenging activity, reducing power and Fe2+ chelating capacity with both milk proteins. Conclusively, the study provided a theoretical base for applications of phytochemicals in the developments of healthier diet and nutraceutical.
      原文链接:
    • NSTL
    • Elsevier

    Continuous-flow manothermosonication treatment of apple-carrot juice blend: Effects on juice quality during storage

    Kahraman, OzanFeng, Hao
    9页
    查看更多>>摘要：The effect of manothermosonication (MTS) treatment on quality of apple-carrot juice blends during storage was examined in comparison with a high temperature-short time (HTST) treatment. The juice blend (90% apple, 10% carrot) with a pH of 4-4.5 was treated by MTS in a custom-designed sonoreactor (20 kHz and 100% amplitude) at 50 and 60 degrees C and 200 kPa for 30s or 60s. The quality attributes of the control and the treated juices were compared on days 0, 7, 14, and 21, including brix, turbidity, color, viscosity, pH, titratable acidity (TA), total phenolic content (TPC), and antioxidant capacity. Changes in trace elements of the juice samples were monitored using X-ray fluorescence (XRF) spectrometry. The antioxidant activity of the MTS samples right after treatment and during storage was significantly higher than that of the HTST-treated. No significant differences on TPC and antioxidant capacity were found between the MTS-treated and the control during storage. The TA, Brix, and turbidity of the MTS samples decreased after treatment and during storage whereas a gradual increase in pH was observed in stored juice samples. A better retention of trace elements was observed in the MTS-treated samples than in the HTST ones.
      原文链接:
    • NSTL
    • Elsevier

    Physicochemical quality attributes and antioxidant properties of set-type yogurt fortified with argel (Solenostemma argel Hayne) leaf extract

    Saleh, AliAl-Juhaimi, Fahad Y.Babiker, Elfadil E.Alqah, Hesham A. S....
    9页
    查看更多>>摘要：The fortification of yogurt with natural bioactive compounds could improve its nutritional and health potentials. In this study, physicochemical, antioxidant, and sensory qualities of set-type yogurt were fortified with different concentrations (0.0, 0.1, and 0.2 g/100 mL) of argel leaf extract (ALE) during cold storage was assessed. Both ALE and storage time affected the quality of yogurt at different magnitudes (p < 0.05). ALE increased the acidity, lactic acid bacteria (LAB) count, water-holding capacity (WHC), viscosity, a* and b* values, springiness, total phenolic contents (TPC), antioxidant activity, and sensory attributes of yogurt. However, it reduced the yogurt's pH, syneresis, L* value, hardness, gumminess, adhesiveness, and thiobarbituric acid (TBARS) value. All yogurt types displayed the behavior of weak viscoelastic gels (G' ' G '', tan delta < 1) that had a predominantly solid-like behavior and better stability during storage. During storage, pH, LAB counts, syneresis, viscosity, a* and b*, TPC, antioxidant activity, and sensory attributes were reduced, whereas acidity, WHC, L*, a* and b*, gumminess, cohesiveness, and TBARS values were increased (p < 0.05). It was concluded that ALE (0.1 and 0.2 mg/100 mL) can be used as a natural ingredient to develop a functional yogurt with improved physical, nutritional, antioxidant, and sensorial qualities.
      原文链接:
    • NSTL
    • Elsevier

    Ionic composition of beer worts produced with selected unmalted grains

    Sterczynska, MonikaStachnik, MartaPoreda, AleksanderPuzynska, Katarzyna...
    7页
    查看更多>>摘要：Brewers' wort should undergo optimized fermentation in order to obtain high-quality beer that meets the specification requirements. This paper presents the impact of increasing the share of unmalted barley and spelled, which are used as adjuncts (5%, 10%, 15%, 20%, 25%, and 30%), and the effect of the mineral content of water on the wort concentration of metal ions (calcium, magnesium, zinc, manganese). Worts made with a combination of deionized water and barley substitute (mainly in 5% and 25% proportions) were characterized by a higher concentration of the ions than those produced with malted barley, or technological water, or spelled.
      原文链接:
    • NSTL
    • Elsevier

    Effect of malaxation temperature on the physicochemical and sensory quality of cv. Cobrancosa olive oil and its evaluation using an electronic tongue

    Marx, Itala M. G.Rodrigues, NunoVeloso, Ana C. A.Casal, Susana...
    9页
    查看更多>>摘要：Olive oil is consumed worldwide due to its appreciated sensory attributes and health benefits, which are related with its fatty acid profile and richness in phenolic compounds that support a health claim concerning olive oil protective effects on blood lipids. However, to ensure that oils possess a rich phenolic content, the extraction conditions can be optimised. Therefore, the effects of malaxation temperature (22, 28 and 34 degrees C) on the physicochemical and sensory characteristics of cv. Cobrancosa olive oils were evaluated. The oils extracted at 22 degrees C had an overall better physicochemical quality (higher total phenols content, greater oxidative stability, lower free acidity and oxidation markers) and more intense positive sensory sensations (higher bitterness and pungency). Additionally, this study showed that a potentiometric electronic tongue could be used to discriminate oils taking into account the effect of malaxation temperature on the overall physicochemical and sensory scores (all samples correctly classified for leave-one-out cross-validation) with a predictive classification similar to that achieved by trained panellists. This finding strengthens the hypothesis that this device could be used as a complementary/alternative taste tool for assessing the impact of the extraction conditions on the oils' physicochemical and sensory characteristics.
      原文链接:
    • NSTL
    • Elsevier

    Microbiological and biochemical performances of six yeast species as potential starter cultures for wet fermentation of coffee beans

    Cox, JulianFrank, DamianZhao, JianElhalis, Hosam...
    8页
    查看更多>>摘要：This study investigated the microbiological and biochemical characteristics of six endogenous yeast species isolated from spontaneous wet coffee fermentation for their potential as starter cultures. The yeasts were cultured under elevated temperature, osmotic pressure, ethanol and acid concentrations to assess their tolerance to these coffee fermentation-related stress conditions. Their ability to produce hydrolytic enzymes for pectin, protein, cellulose and starch were evaluated using plate assays. Hanseniaspora uvarum and Pichia kudriavzevii were the most stress-tolerant species and also exhibited high pectinase, amylase, cellulase and protease activities compared with P. fermentans, Candida railenensis, C. xylopsoci and Wickerhamomyces anomalus. When the yeasts were inoculated in a synthetic coffee pulp extract medium all the isolates grew and produced several important aromatic compounds, including isoamyl alcohol, 2-phenylethyl alcohol, ethanol, ethyl acetate, acetaldehyde, and 2-propanone. The concentrations of these volatiles produced by the yeast species differed significantly. H. uvarum and P. kudriavzevii produced significantly higher concentration of total alcohols (42.5, 57.6 mg/l), esters (31.0, 33.7 mg/l) and aldehydes (0.7, 1.9 mg/l). Overall, H. uvarum and P. kudriavzevii demonstrated the strongest potential as starter cultures for wet coffee fermentation.
      原文链接:
    • NSTL
    • Elsevier

    Storage temperature of tiger nuts (Cyperus esculentus L) affects enzyme activity, proximate composition and properties of lactic acid fermented tiger nut milk derived thereof

    Kizzie-Hayford, NazirDabie, KwabenaKyei-Asante, BaffourAmpofo-Asiama, Jerry...
    7页
    查看更多>>摘要：The impact of storage temperature on tiger nut's (Cyperus esculentus L.) enzyme activity, proximate composition, and on the fermentation kinetics and sensory properties of lactic fermented tiger nut milk was investigated. Storage temperature significantly affected the protein, fat, fiber, ash and carbohydrate content of tiger nuts. Refrigeration of tiger nuts resulted in higher activities of a-amylase and lipase, whilst ambient or elevated storage showed higher sugar content of tiger nuts. Fermentation of tiger nut milk that was prepared from ambient-stored tiger nuts showed an increased rate of pH reduction and, hence, a significantly lower fermentation time. Fermented tiger nut milk from freshly harvested tiger nuts was more frequently described as grassy and raw. Storage of tiger nuts at ambient or elevated temperature led to lactic fermented tiger nut milk with sweet and sour attributes, and can be significant for improving the sensory quality.
      原文链接:
    • NSTL
    • Elsevier

    Stability of milk chocolate with hygroscopic fibers during storage

    Verde, Alessandra BarrosAlvim, Izabela DutraLuccas, ValdecirVercelino Alves, Rosa Maria...
    9页
    查看更多>>摘要：The addition of fibers to chocolates improves their nutritional profile by adding prebiotics and allows for a reduction in the sugar content. This study aimed to evaluate the influence of the packaging materials on the quality preservation of chocolates containing hygroscopic fibers. Thus, three types of chocolate bars were produced: standard, with inulin and with fructo-oligosaccharide (FOS). The products were stored at 20 +/- 1 degrees C/75 +/- 5%RH for 270 days in three types of packaging: biaxial oriented polypropylene (BOPP)/metallized (met) BOPP, BOPP/BOPP and Cellophane, and analyzed for moisture, water activity, particle diameter, morphology and sensory test. After 120 days, the chocolate with FOS in Cellophane presented a greater increase in moisture than the same product in the other packaging materials. However, in the sensory test the judges did not perceive this change since particle perception was low and all the chocolates obtained acceptance scores above 6 on a 9-point scale for color, flavor and global acceptance and high probability of buying. It was concluded that chocolates with fibers packed in BOPP/metBOPP and BOPP/BOPP preserved the milk chocolate at 20 degrees C/75%RH for 270 days, but the use of renewable source materials such as Cellulose could result in a shorter shelf life due to their higher water content.
      原文链接:
    • NSTL
    • Elsevier

    The effect of simulated vibration frequency on the physico-mechanical and physicochemical properties of peach during transportation

    Dagdelen, CigdemAday, Mehmet Seckin
    8页
    查看更多>>摘要：Loss in fresh fruit and vegetables during transportation occurs mainly due to their susceptibility to mechanical damage. The quality loss caused by this damage depends on the shock and vibration frequencies. In this study, the effect of different vibration frequencies (5 Hz, 10 Hz, and 15 Hz) on the physico-mechanical and physicochemical properties of peach was investigated. The parameters such as energy absorption, mechanical hysteresis, and deformation volume were increased whereas mean geometric diameter, surface area, volume, degree of elasticity, deformation energy, and modulus of elasticity were decreased. Regarding physicochemical properties, pH and total soluble solid parameters increased whereas lightness (L*) value of peach decreased. The highest level of damage and mold growth were observed on the peach treated with 15 Hz frequency followed by 10 Hz and 5 Hz, respectively. The effect of all the frequencies on the physico-mechanical and physico-chemical properties of peach was statistically different. The results indicated that the increase in the vibration frequency causes higher mechanical damage in peach.
      原文链接:
    • NSTL
    • Elsevier