解淀粉芽孢杆菌发酵液处理提高辣椒采后品质

为了解解淀粉芽孢杆菌 strain-L 发酵液对辣椒采后保鲜效果,以不同辣椒品种（海青椒、红尖椒）为试材,研究了strain-L发酵液对辣椒保鲜效果的影响。体内体外试验结果表明不同浓度strain-L发酵液对链格孢菌具有较好的抑菌效果。损伤接种25℃下贮藏7 d,strain-L的发酵液对海青椒和红尖椒都具有明显的防腐效果,海青椒的腐烂率与无菌水相比下降了51.87%,红尖椒的腐烂率与无菌水相比下降了58.54%。非损伤接种9℃下贮藏24 d,strain-L发酵液对不同辣椒品种的保鲜效果存在差异,在整个贮藏期间,strain-L发酵液处理可降低辣椒采后腐烂率,明显优于无菌水组。贮藏24 d后,青椒发酵液处理和保鲜液处理的腐烂率分别为37.5%、32.50%,与无菌水组相比,分别降低了35%和40%。红尖椒的发酵液处理和保鲜液处理的腐烂率分别为29.63%、24.14%,与无菌水组相比降低了34.19%、28.70%,不同品种间,发酵液处理组和保鲜液处理组的腐烂程度不同,且在整个贮藏期间,strain-L发酵液延缓了果实内还原糖含量、可溶性固形物、可溶性蛋白和VC含量的降低,保持了辣椒较稳定的色泽和质构。strain-L发酵液在保持辣椒较好的商品价值、感官品质以及营养价值方面获得了较好的贮藏效果,为采后生物防控与保鲜提供理论依据和技术方法。     

施加外源乙烯时机对MA贮藏桃果实品质的影响

为了改善桃果实低温贮藏期间品质降低情况,探讨了大久保桃果实在低温条件下自发气调（MA）贮藏期间,不同时间（0、15和30 d）加入外源乙烯处理（50～80 μL/L）的效果,测定在贮藏期间及20℃下回温3 d后果实的硬度、可溶性固形物含量（SSC）、腐烂指数、可滴定酸（TA）、总糖、维生素C（Vc）的含量。结果表明,在0℃下MA贮藏15、30 d加入外源乙烯处理能较好地保持果实的质地、可溶性固形物含量,降低桃果实的腐烂率。同时15 d时加入外源乙烯处理还能较好地保持总糖和Vc含量,但对可滴定酸的影响与其他MA处理差异不显著。研究表明,MA贮藏大久保桃果实在第15天进行外源乙烯处理效果最好。     

适宜微波处理保持山核桃贮藏品质

为了研究微波热处理对山核桃贮藏品质的影响,将新鲜山核桃（500 g）在微波（2455 MHz,650 W）下分别进行1,2.5,3和5 min 热处理,然后置于温度：(2±0.5)℃,相对湿度：70%～80%的环境中贮藏120 d。贮藏期间对山核桃营养成分,品质变化,感官指标进行监测。结果显示2.5 min 的微波处理能够显著（P<0.05）延缓蛋白质、脂肪的降低,对脂肪酸和维生素 E 有较好的保存效果,此外,2.5 min 微波处理能够减慢贮藏期间山核桃水分和可溶性糖的流失速度,维持较好的感官品质。同时2.5 min 微波处理对脂肪酸败有很好的抑制效果,在贮藏120 d,山核桃保持了较好的品质。与2.5 min 相比较,较短时间（1 min）和较长时间（3和5 min）微波处理没有提高山核桃贮藏期间的营养品质,1 min 的微波处理对贮藏期间山核桃脂肪、蛋白、脂肪酸、过氧化值（peroxide value）、生育酚等营养几乎贮藏无影响（P>0.05）,3和5 min 处理显著（P<0.05）加剧了各项营养指标的衰败速度,因此2.5 min为适宜的微波处理条件。该研究为微波保鲜山核桃提供理论依据。     

适宜微波处理保持山核桃贮藏品质（英文）

为了研究微波热处理对山核桃贮藏品质的影响,将新鲜山核桃(500 g)在微波(2 455 MHz,650 W)下分别进行1,2.5,3和5 min热处理,然后置于温度:(2±0.5)℃,相对湿度:70%~80%的环境中贮藏120 d。贮藏期间对山核桃营养成分,品质变化,感官指标进行监测。结果显示2.5 min的微波处理能够显著(P0.05)延缓蛋白质、脂肪的降低,对脂肪酸和维生素E有较好的保存效果,此外,2.5 min微波处理能够减慢贮藏期间山核桃水分和可溶性糖的流失速度,维持较好的感官品质。同时2.5 min微波处理对脂肪酸败有很好的抑制效果,在贮藏120 d,山核桃保持了较好的品质。与2.5 min相比较,较短时间(1 min)和较长时间(3和5 min)微波处理没有提高山核桃贮藏期间的营养品质,1 min的微波处理对贮藏期间山核桃脂肪、蛋白、脂肪酸、过氧化值(peroxide value)、生育酚等营养几乎贮藏无影响(P0.05),3和5 min处理显著(P0.05)加剧了各项营养指标的衰败速度,因此2.5 min为适宜的微波处理条件。该研究为微波保鲜山核桃提供理论依据。     

NO处理对草莓果实采后品质和苯丙烷类代谢的影响

为探讨NO处理在草莓果实采后保鲜中的作用机制,以红艳草莓为材料,定期测定草莓果实室温下的品质、抗氧化物质含量、细胞膜脂质过氧化程度和苯丙烷类代谢的变化。结果表明,NO熏蒸处理能有效抑制草莓果实采后腐烂,其最优浓度为20μL·L~(-1)。NO处理可显著抑制草莓果实贮藏期间可溶性固形物含量的下降,降低细胞膜过氧化程度,保持较好品质;也可显著提高草莓果实中苯丙氨酸解氨酶、4-香豆酰辅酶A连接酶、肉桂醛羟化酶和查尔酮异构酶等苯丙烷类代谢相关酶的活性,增加总酚、花色苷和总黄酮的积累,提高草莓果实的抗氧化活性。因此,适宜浓度的NO处理(20μL·L~(-1))可提高草莓果实贮藏品质,延长保鲜期。本研究为丰富草莓果实采后保鲜技术提供了较好的理论和应用价值。     

ClO2处理对兰州百合低温贮藏的防腐保鲜效果

为了探索食用百合鳞茎采后耐久保鲜方法,以兰州百合鳞茎为试材,研究了ClO2处理对百合鳞茎在（-3±1）℃贮藏温度下的防腐保鲜效果。结果表明：不同浓度ClO2熏蒸处理1?h均能降低百合贮藏期间的腐烂指数,其中6?mg/L 浓度ClO2处理时腐烂指数最低,该处理也降低了百合贮藏期间的呼吸强度,抑制了贮藏期间可滴定酸和丙二醛含量的升高、维生素C含量的降低和贮藏后期可溶性糖含量的降低,保证了百合鳞茎贮藏期间的风味品质。ClO2浓度较低或过高时,保鲜效果均有所降低。研究结果认为适宜浓度的ClO2可作为防腐保鲜剂在百合鳞茎的实际贮运中应用。     

浸钙对黑宝石李果实采后品质和延缓衰老的影响

采用不同浓度CaCl₂溶液浸泡黑宝石李采后果实,研究对其果实品质和延缓衰老的影响,达到延长贮藏期的目的。 结果表明：浸钙处理可显著抑制采后贮藏过程中果实可滴定酸含量、硬度和可溶性糖含量的下降,浸钙处理降低了果实可溶性固性物含量;贮藏期间浸钙处理后乙烯释放量显著低于对照,且峰值出现的时间比对照推迟15 d;浸钙处理可保持采后贮藏过程中果实较高的超氧化物歧化酶(SOD)活性和较低的丙二醛(MDA)含量,维持细胞内活性氧代谢平衡,显著降低膜脂过氧化作用,从而延缓果实成熟衰老进程,较好的保持了果实品质。4种钙浓度处理中以1％和2％CaCl₂溶液浸果效果较好。     

草莓涂膜保鲜研究

试验研究以"蜂胶/魔芋胶"为原料制成的复合保鲜液涂膜处理对草莓贮藏保鲜品质的影响,测定比较魔芋胶涂膜,蜂胶涂膜对草莓的感官品质、失重率、维生素C含量及可溶性固形物等指标的影响。结果表明:"蜂胶/魔芋胶"复合涂膜液对草莓保鲜效果较好,15d后的失重率仅为8.53%,维生素C含量为59.68mg/100g,可溶性固形物含量为7.26%。综合比较3种复合保鲜液,"蜂胶/魔芋胶"复合涂膜液有效地减少了营养成分和水分的损失,可延长货架期和保持其最佳食用品质。     

茉莉酸甲酯对蓝莓贮藏品质及抗病相关酶活性的影响

研究不同浓度(0、10、20、30μmol·L-1)茉莉酸甲酯(MeJA)熏蒸处理对蓝莓贮藏品质及抗病相关酶活性的影响,为蓝莓采后保鲜技术研究和应用提供参考。结果表明:蓝莓在5℃贮藏条件下,MeJA处理能保持较高的好果率,且能抑制果实硬度下降和糖酸含量的降低,其中10、20μmol·L-1MeJA处理贮藏品质较好;MeJA处理对蓝莓果实中苯丙氨酸解氨酶(PAL)、过氧化物酶(POD)、多酚氧化酶(PPO)有激活作用,其中20μmol·L-1MeJA浓度处理更有利于诱导抗病酶的活性,提高果实抗病性,为蓝莓采后较适宜的处理浓度。     

精准温度控制对枸杞鲜果贮藏品质和香气成分的影响

为研究精准温控技术在枸杞鲜果保鲜中的应用效果,将枸杞分别装入泡沫箱（Control Check,CK）、泡沫箱+蓄冷剂（冰温）和精准温控箱+蓄冷剂（相温）中,记录箱内温度,结合贮藏期间枸杞的品质变化,通过主成分分析法对3组枸杞进行综合评价,并对不同处理香气成分进行分析。结果表明,精准温度控制后箱体内部温度更低,且温度波动保持在0.1 ℃以内,CK组、冰温组、相温组枸杞出现发霉腐烂现象的时间分别为10、20、40 d;贮藏40 d后,相温组枸杞的腐烂率为4.11%,远低于CK组的14.85%,色差低于3,亮度达34.12,可溶性固形物含量、可滴定酸含量、维生素C含量、类胡萝卜素含量分别较CK组高0.65个百分点、0.03个百分点、4.34 mg/100g、2.90 mg/g,相温组枸杞有效抑制腐烂率和失重率的增加,延缓色差的升高和亮度的降低,保持较高的可溶性固形物、可滴定酸、维生素C和类胡萝卜素含量,经主成分得分分析后得到3组枸杞的品质排序为相温组、冰温组、CK组,且精准温度控制贮藏的枸杞醛类、萜类等有利香气成分相对含量更高。因此,精准温度控制技术有利于枸杞鲜果的冷藏保鲜,其中相温贮藏效果更好。研究结果为枸杞鲜果精准温控保鲜提供参考。     

糖接枝处理改善大豆蛋白纤维聚集体泡沫稳定性

为了探究糖接枝对大豆蛋白纤维聚集行为和泡沫性质的影响,明确蛋白质结构与功能的关系,该研究以大豆蛋白(soy protein isolation,SPI)和乳糖(lactose)为原料,通过干热法制备糖接枝大豆蛋白(SPI-lactose conjugate,SPI-Lac),以及在酸性条件下加热诱导其形成纤维聚集体(p H值2.0),制备了一种糖接枝大豆蛋白纤维聚集体(SPI-lactose conjugate fibillar aggregates),并考察了糖接枝对大豆蛋白的纤维聚集行为及泡沫性质的影响。研究结果表明:大豆蛋白在酸性条件下(p H值2.0)经加热后会发生水解,同时水解产物不断聚集形成大分子的纤维聚集体。糖接枝导致大豆蛋白的水解速度下降,但荧光光强和粒径的结果表明糖接枝能增强纤维聚集能力。SPI-Lac在中性条件下的溶解度(p H值5.0—7.0)显著高于SPI(P0.05),且不同时间处理的SPI-Lac纤维聚集体均能改善SPI在酸性条件下的溶解度(p H值2.0—5.0)。此外,不同时间处理的SPI-Lac纤维聚集体在酸性条件下的起泡能力均高于SPI纤维聚集体。SPI和SPI-Lac纤维聚集体的形成会导致SPI起泡能力的下降,但是短时间酸热处理形成的纤维聚集体泡沫稳定性得到显著改善。因此,糖接枝结合短时间酸热处理制备的糖接枝大豆蛋白纤维聚集体在中性条件下的泡沫稳定性显著提高(P0.05),是合理有效的蛋白质改性方法。     

Preparation and characterization of papain-modified sesame (Sesamum indicum L.) protein isolates

Defatted sesame meal ( approximately 40-50% protein content) is very important as a protein source for human consumption due to the presence of sulfur-containing amino acids, mainly methionine. Sesame protein isolate (SPI) is produced from dehulled, defatted sesame meal and used as a starting material to produce protein hydrolysate by papain. Protein solubility at different pH values, emulsifying properties in terms of emulsion activity index (EAI) and emulsion stability index (ESI), foaming properties in terms of foam capacity (FC) and foam stability (FS), and molecular weight distribution of the SPI hydrolysates were investigated. Within 10 min of hydrolysis, the maximum cleavage of peptide bonds occurred as observed from the degree of hydrolysis. Protein hydrolysates have better functional properties than the original SPI. Significant increase in protein solubility, EAI, and ESI were observed. The greatest increase in solubility was observed between pH 5.0 and 7.0. The molecular weight of the hydrolysates was also reduced significantly during hydrolysis. These improved functional properties of different protein hydrolysates would make them useful products, especially in the food, pharmaceutical, and related industries.     

Optimization of the enzymatic deamidation of soy protein by protein-glutaminase and its effect on the functional properties of the protein

The effects of enzymatic deamidation by protein-glutaminase (PG) on the functional properties of soy protein isolate (SPI) were studied. Conditions for the deamidation were evaluated by means of response surface methodology (RSM). Optimal conditions based on achieving a high degree of deamidation (DD) with a concurrently low degree of hydrolysis (DH) were 44 °C, enzyme:substrate ratio (E/S) of 40 U/g protein and pH 7.0. Under optimal conditions, both DD and DH increased over time. SDS-PAGE results indicated that lower molecular mass subunits were produced with increasing DD. Far-UV circular dichroism spectra revealed that the α-helix structure decreased with higher DD, while the β-sheet structure increased until 15 min of deamidation (32.9% DD), but then decreased at higher DD. The solubility of deamidated SPI was enhanced under both acidic and neutral conditions. SPI with higher DD showed better emulsifying properties and greater foaming capacity than SPI, while foaming stability was decreased. It is possible to modify and potentially improve the functional properties of SPI by enzymatic deamidation using PG.     

Foaming properties of wheat gliadin

We studied gliadin solubility, surface tension and foam behavior, and the presence of different gliadin types in gliadin aqueous solutions and foams as a function of pH. Gliadin has excellent foaming properties only at neutral and alkaline pH. Its solubility is minimal near neutral pH, while almost complete at acidic and alkaline pH. Surface tensions of gliadin solutions are minimal around neutral pH, higher at alkaline pH, and highest at acidic pH, which corresponds well with their respective foaming properties. Foams at acidic and alkaline pH values are enriched in γ-gliadin, while foams at pH 8.0 have a similar distribution of α- and γ-gliadins. Thus, γ-gliadin predominantly contributes to the foaming properties of gliadin. The poor foaming properties of gliadin at pH 2.0 improve in the presence of 0.25 and 1.0% NaCl. It follows that the presence of positively charged amino acid residues hinders the formation of stable foam at acidic pH.     

Formation of stable covalent dimer explains the high solubility at pH 4.6 of lactose-beta-lactoglobulin conjugates heated near neutral pH

The solubility of lactose-beta-lactoglobulin conjugates at pH 4.6, after heating near neutral pH in phosphate buffer/0.116 M NaCI, was investigated by size exclusion chromatography and compared with unmodified protein. Heated conjugates in the temperature range 65-90 degrees C showed greater solubility at pH 4.6. The proportion of soluble protein increased with the number of bound lactose molecules. Total solubility was obtained for conjugates with nine lactose residues attached per monomer of beta-lactoglobulin. The protective effect of bound sugar toward precipitation was associated with the formation of soluble disulfide cross-linked dimers, highly accessible to trypsin digestion. These results suggested that bound lactose, through steric hindrance and high surface hydrophilicity, prevents the thiol-disulfide exchange reactions of the polymerization-aggregation process of lactose-beta-lactoglobulin conjugates.     

高压微射流压力对大豆蛋白-大豆多糖体系功能性质的影响

为提升大豆分离蛋白（soy protein isolate,SPI）的功能性质,该文引入大豆可溶性多糖（soybean soluble polysaccharides,SSPS）,构建大豆分离蛋白-大豆可溶性多糖体系（SPI-SSPS）,研究动态高压微射流（dynamic high-pressure microfluidization,DHPM）处理对SPI-SSPS功能特性的影响。分别采用0,60,100,140和180 MPa的 DHPM压力处理SPI-SSPS,探究不同压力对SPI-SSPS起泡特性、乳化特性、溶解性、粒度分布和表面疏水性的影响。结果表明,DHPM处理能提高SPI的溶解性和起泡特性,且SSPS的存在能显著提高DHPM对SPI功能性质的改善效果（P<0.05）。100和60 MPa的DHPM处理能使SPI-SSPS呈现较高的起泡能力和起泡稳定性,分别为未处理样品的1.2和2.4倍。140 MPa的DHPM处理使SPI-SSPS溶解性较强,为未处理样品的1.8倍。然而,DHPM处理会显著降低SPI-SSPS的乳化特性、粒径和表面疏水性（P<0.05）。随着处理压力的增加,SPI-SSPS的粒度和表面疏水性逐渐降低,在180MPa的DHPM处理下SPI-SSPS具有较小的粒径和较低的荧光强度。综上所述,DHPM结合SSPS改性技术可用于改善SPI的功能性质（如溶解性、起泡性）,促进SPI在食品工业的应用。该文的研究结果可为SPI的功能性质改性提供参考。     

Functional properties of purified vicilins from cowpea (Vigna unguiculata) and pea (Pisum sativum) and cowpea protein isolate

The major storage globulins (vicilins) of cowpea (Vigna unguiculata) and pea (Pisum sativum) seeds were purified by ammonium sulfate precipitation, and a semipurified cowpea protein isolate (CPI) was prepared by isoelectric precipitation. Some of the functional properties of these proteins, including solubility, foaming, and emulsifying capacities, were investigated and compared. The solubility of purified cowpea vicilin was reduced at pH 5.0, increasing markedly below and above this value. Pea vicilin exhibited poor solubility between pH 5.0 and pH 6.0, and CPI was little soluble in the pH range from 4.0 to 6.0. At neutral pH, the emulsifying activity indexes (EAI) of purified pea vicilin and CPI were 194 and 291 m(2)/g, respectively, which compare quite favorably to EAIs of 110 and 133 m(2)/g for casein and albumin, respectively. Remarkably, purified cowpea vicilin exhibited an EAI of 490 m(2)/g, indicating a very high emulsifying activity. Purified cowpea and pea vicilins exhibited lower foaming capacities and foam stablity indexes (FSI) than CPI. FSI values of 80 and 260 min were obtained for purified pea and cowpea vicilin, respectively, whereas a FSI value of 380 min was obtained for CPI. These results are discussed in terms of the possible utilization of purified vicilins or protein isolates from pea and cowpea in the food processing industry.     

Porphyran as a functional modifier of a soybean protein isolate through conjugation by the Maillard reaction

Porphyran (Por) prepared from dried nori was applied as a functional modifier of a soybean protein isolate (SPI) to conjugate with SPI from defatted soybean by the Maillard reaction (79% relative humidity and 60 degrees C for 7 days). Two kinds of partially denatured conjugate (Conj 45 and Conj 63) were obtained from the reaction product by sequential extraction at pH 4.5 and pH 6.3, and the respective yield and weight ratios of the SPI and Por moieties were 8.4% and 1:1 for Conj 45 and 11.7% and 1:0.16 for Conj 63. Conj 63 demonstrated improved solubility between pH 5.0 and pH 8.0, while Conj 45 exhibited substantially complete solubility over the pH range of 2.0-8.0. Conj 63 showed more tolerance against digestion with pancreatin than SPI, whereas this was lost after denaturation. Conj 63 and Conj 45 both showed a markedly higher emulsion activity index and emulsion stability than SPI, even at pH 3.0; in particular, Conj 45 exhibited outstanding emulsifying ability. Conj 63 had about a two-fold higher calcium-binding ability than SPI, and Conj 63 and Conj 45 did not aggregate with added Ca2+ and Mg2+. It is believed that Por could be a valuable functional modifier of SPI for providing soybean protein-based liquid foods such as beverages by conjugation through the Maillard reaction.     

Glucose slows down the heat-induced aggregation of β-lactoglobulin at neutral pH

The behavior of β-lactoglobulin (β-Lg) during heat treatments depends on the environmental conditions. The influence of the presence or absence of a reducing sugar, namely, glucose, on the modification of the protein during heating has been studied using fluorescence, polyacrylamide gel electrophoresis (PAGE), size-exclusion chromatography (SEC), and transmission electron microscopy. Glycated products were formed during heating 24 h at 90 °C and pH 7. The fluorescence results revealed an accumulation of the advanced Maillard products and the formation of aggregates during heating. PAGE and SEC data suggested that the products in the control samples were essentially composed of covalently linked fibrillar aggregates and that their formation was faster than that for glycated samples. We showed that glucose affected the growing step of covalent aggregates but not the initial denaturation/aggregation step of native protein. Glucose-modified proteins formed a mixture of short fibrils and polydisperse aggregates. Our results revealed that β-Lg forms fibrils at neutral pH after heating and that glucose slows the formation of these fibrils.     

Effect of moisture content during dry-heating on selected physicochemical and functional properties of dried egg white

This article addresses the effect of moisture content (0.8-9.9%) during dry-heating (80 degrees C) on selected physicochemical (solubility, turbidity, residual denaturation enthalpy, aggregation, surface hydrophobicity, and sulfhydryl content) and functional (foaming ability, foam density, and stability) properties of freeze-dried egg white (FDEW). Moisture content during dry-heating proved to be a parameter determining the functionality of the resulting egg white powder. The degree of conformational changes induced in the egg white proteins by dry-heating was strongly dependent on the amount of water present. Preferentially, dry-heating at 80 degrees C should be performed on egg white powder with a moisture content below 6.8%, as the loss of protein solubility above this value is extensive. In addition to insoluble aggregates, soluble, strongly stabilized aggregates were also formed, especially at higher moisture contents. The decrease in denaturation enthalpy, increase in surface hydrophobicity, and exposure of SH groups previously hidden in the protein core and their subsequent oxidation were more pronounced at prolonged dry-heating times and at higher moisture contents. These conformational changes resulted in improved foaming ability and foams with lower density. No effect of dry-heating on the foam stability was observed.