Physicochemical Properties of Sweet Potato Flour and Starch as Affected by Blanching and Processing

The effects of blanching on physicochemical properties of flours and starches prepared from two varieties of sweet potatoes (Mun‐Kai and Negro) were studied and compared. The pasting temperature and peak viscosity of starches, respectively, were 74 and 80 °C and 381 and 433 RVU. The pasting temperature (74.0‐94.8 °C) of flours was greater than that of starch, depending on the variety and blanching process. However, the peak viscosity (ca. 103‐120 RVU) of flours was lower than that of the corresponding starches. Partial gelatinization of starch granules was observed as a result of a 1‐min blanching. Composition of starch and flour was found to affect swelling power and solubility. The starch content of starches, flours from unblanched sweet potato and flours from 1‐min blanched sweet potatoes were 97; 66.3 and 74.9; as well as 36.6 and 40.4%, respectively. Amylose content of flours and starches varied from 17.2‐20.8%.     

Physicochemical Properties of Mango Seed Flour

The proximate composition, functional and antinutritional properties of flour produced from seeds of mangoes grown in Ebonyi State were studied. Two cultivars: India and Indochinese were used for the study. The aim of the study was to determine any possible potential that flour obtained from these seeds might possess. Results revealed that flours from India and Indochinese cultivars had protein contents of 6.00 and 4.95%; moisture, 5.00 and 10.36%; fibre, 11.00 and 15% while the carbohydrate was 74.41 and 64.23% respectively. Results from the functional properties showed that flours from both of the cultivars had water absorption capacities of 2.0 g/g and 1.5 g/g; oil absorption capacity of 2.16 g/g and 1.83 g/g while foaming capacity was 3.79 g/g and 3.75 g/g with India cultivar having higher values for each of the functional properties studied although, there was no significant difference (p > 0.05) in the values except for the water absorption capacity. Levels of hydrogen cyanide, phytic acid and trypsin inhibitors were generally low and within safe levels.     

Effects of Blanching on Some Physical Properties and Processing Recovery of Sweet Corn Cobs

The effects of the blanching process of sweet corn on shearing stress, shearing energy, and processing recovery of kernels as well as weight and dry substance of kernels and cobs were studied. Sweet corn cobs were blanched in water, where blanching time ranged from 2 to 8 min and temperature ranged from 75 to 100 °C. Nonblanched cobs (fresh cobs) were used as control samples. It was found that all analyzed variables were significantly affected by blanching time and temperature. The average values of all analyzed variables, except moisture which decreased, increased with increasing of the blanching time and temperature. Changing the blanching time and temperature affected the dry substance of kernels and cobs, kernel and cob mass, recovery processing by increasing it, as well as the average values of shearing stress and shearing energy by decreasing them.     

Yield Stress and Time-dependent Rheological Properties of Mango Pulp

Mango pulp was tested for time-independent and time-dependent flow properties using a coaxial cylinder rheometer. Mango pulp is a pseudoplastic liquid with yield stress, and exhibits thixotropic properties. The yield stress calculated using the Casson or Bingham plastic models, had markedly higher values than those determined by stress relaxation, controlled stress experiments, or from stress-strain plots. The yield stress of mango pulp tested in this experiment was sensitive to temperature and decreased rapidly as temperature increased. The time-dependent model of Weltman was found to be most applicable (|r| 0.991, p 0.01) for mango pulp.     

超声处理对龙眼果肉多糖理化特征及免疫调节活性的影响

超声波广泛用于龙眼果肉多糖的浸提以实现提取率的大幅增加,但对其生物活性的影响尚不清楚。采用不同功率超声处理干制和新鲜龙眼果肉粗多糖(LPD和LPF),以凝胶色谱法分析分子量分布发现:经150~450 W超声处理15 min后,因高分子量级分降解,LPD和LPF的分子量分布发生明显变化,且其降解行为也由逐渐减小的特征粘度所印证,而不同功率之间的影响差异不明显。超声处理还能解离LPD中大部分O型糖苷键以及LPF高分子量级分中非O型糖苷键结合的蛋白。体外免疫调节活性评价发现:超声处理不同程度地减弱LPD和LPF(50~400μg/m L)对脾淋巴细胞增殖、巨噬细胞吞噬和NO生成的刺激活性,可能源于高分子降解和结合蛋白解离;LPD经超声降解后在400μg/m L剂量下对Con A诱导淋巴细胞增殖的刺激活性显著增强(p0.05),推测与粘度降低有关。超声波对龙眼多糖分子的降解作用导致其体外免疫调节活性明显减弱。     

赋形剂对冻干西番莲果粉理化特性及抗氧化活性的影响

针对西番莲果浆在真空冷冻干燥过程中物料营养物质损失及终产品易吸湿潮解等技术难点,通过添加赋型剂麦芽糊精(MD)、阿拉伯胶(AG)、乳清分离蛋白(WPI)和大豆分离蛋白(SPI),研究西番莲果粉在制备过程中吸湿性、水分含量、维生素C保留率、DPPH自由基清除率的变化规律,并对果粉的玻璃化转变温度和形貌特点进行分析。研究表明,添加麦芽糊精使得果粉的玻璃化转变温度从62.30 ℃增加到89.87 ℃,并有效降低其吸湿性至10.69%;添加阿拉伯胶（15%）可以有效降低果粉终产品的水分含量,从4.15%降低至1.56%;而添加乳清分离蛋白使得果粉的维生素C保留率由54.16%提高至91.85%,DPPH自由基清除率由36.81%提高至61.89%。添加赋形剂有助于西番莲果浆在冻干过程中保持疏松多孔结构,且在果粉的表面可能形成类似包覆层的保护膜或类似微胶囊的包埋结构,防止果粉中的糖类结块粘连,保护产品的品质。     

微滤膜材质对杨梅汁理化品质及抗氧化活性的影响

为了寻找适合杨梅汁澄清处理的微滤膜,选用聚醚砜膜(PES)、尼龙膜(Nylon)、醋酸纤维膜(CA)、聚偏氟乙烯亲水膜(PVDF)、聚四氟乙烯亲水膜(PTFE)和聚丙烯膜(PP)6种材质的微滤膜,研究不同材质滤膜对杨梅汁理化品质的影响.结果表明:6种材质的滤膜均能有效提高杨梅汁的透光率,降低果汁中蛋白质含量;不同材质滤...     

不同干燥方式对甘蓝理化性质和抗氧化活性的影响

为研究不同干燥方式对甘蓝理化性质和抗氧化活性的影响,改善干制甘蓝的品质,提高甘蓝附加值,本试验采用65 ℃热风干燥、1 kW微波干燥、热风-微波联合干燥处理甘蓝,测定干燥后甘蓝的色泽、V_C、游离酚、总酚含量和抗氧化活性,并对抗氧化相关指标进行相关性分析。结果表明:联合干燥的甘蓝色泽最佳,ΔE值为15.01±0.59;不同干燥方式甘蓝总酚和游离酚含量差异显著(P<0.05),而酚的存在状态变化较小;干燥后甘蓝抗氧化能力有一定程度的降低,微波干燥甘蓝V_C、游离酚、总酚含量均最高,分别为23.14 mg/100 g FW、80.22、124.85 mg GAE/100 g FW,保留率分别为67.3%、90%、86.6%,其中DPPH、ABTS自由基清除能力和Fe³⁺还原能力最强。相关性分析显示:不同干燥方式甘蓝V_C、酚类与抗氧化活性之间呈显著相关(P<0.05)。因此,甘蓝采用微波干燥方式优于热风干燥和热风-微波联合干燥,现有的干燥生产线可尝试结合微波干燥技术,以提高干制品的品质。

     

胶磨破碎和冷冻破碎对芒果浆品质的影响

该研究以芒果为原料,比较胶磨破碎和冷冻破碎对芒果浆品质的影响。研究发现：两种破碎方式对芒果浆的水分、灰分、蛋白质、总酸、总糖、纤维含量无显著影响（P>0.05）。胶磨破碎芒果浆的总酚含量、ABTS+自由基清除能力分别为27.42 mg GAE/100 g、9.04 μmol TE/g,冷冻破碎芒果浆分别为31.18 mg GAE/100 g、9.75 μmol TE/g,说明冷冻破碎能够更好的保护芒果浆的抗氧化活性。胶磨破碎芒果浆粒径为110.34 μm,冷冻破碎芒果浆粒径只有59.49 μm,说明冷冻破碎芒果浆质地更加细腻,分散程度有所提高。冷冻破碎芒果浆的L*值、a*值、b*值均显著高于胶磨破碎果浆（P<0.05）;萜烯类化合物总量为1 805.56 μg/L,明显高于胶磨破碎芒果浆的416.96 μg/L。冷冻破碎芒果浆在芒果味、青草味、细腻度的感官评价指标评分更高,具有更好的色泽、风味和食用品质。综上,冷冻破碎芒果浆在抗氧化活性、微观结构、感官品质等方面更佳。冷冻破碎能够更好的保护芒果浆的品质,可作为一种新型芒果浆加工技术。     

Enzymatic Maceration: Effects on Volatile Components of Mango Pulp

A decrease of 50% or more of the relative viscosity of mango pulp resulted from different times of maceration with pectolyase and with 3 of the 4 commercial enzyme preparations tested. The microscopic observations after treatment I showed a suspension of cells without destruction of cell walls, fiber remaining in some cases. There was no significant degradation of cellulose and a slight degradation of hemicellulose during treatment. A stability test based on i centrifugation indicated that the macerate was stable for a i relative viscosity decrease <50%. Aroma compound concentrations were not significantly affected by the pectolyase treatment, as only 6 oxygenated terpene compounds, probably released by acid hydrolysis from glycosides were noted.     

超声处理对红豆蛋白理化性质及抗氧化功能的影响

本试验以脱脂红豆蛋白为原料,利用水解度、起泡性以及总抗氧化能力等指标研究不同超声功率及时间对红豆蛋白理化性质及抗氧化功能的影响规律。结果表明:在超声功率400 W处理20 min后,红豆蛋白的水解度与溶解度达到最大值,分别由3.39%增加至21.30%,46.77%增加至79.63%;乳化性及乳化稳定性显著增强（P<0.05）,在超声功率400 W处理10 min后分别提高了78.62%、43.94%;与空白对照相比,当超声功率400 W处理10 min时红豆蛋白的起泡性最好,增加了70.31%,超声功率不变,时间延长至20 min时起泡稳定性最强,增加了11.15%;超声处理使红豆蛋白的游离巯基含量显著提高（P<0.05）,二硫键含量显著降低（P<0.05）;总抗氧化能力在超声功率160 W处理30 min时抗氧化能力最佳（681.20 U/mL）,DPPH自由基清除能力与Fe离子还原能力在功率400 W、10 min时最佳,分别提高了78.23%、33.52%。超声处理能够明显改善红豆蛋白理化性质,提高其抗氧化能力。     

茶多酚对普鲁兰-明胶膜理化及抗氧化、抗菌性能的影响

茶多酚因其优异的抗氧化和抗菌性能,在食品领域被广泛应用。通过制备茶多酚-普鲁兰-明胶复合生物活性膜,研究茶多酚的质量分数(0%、2%、4%、6%、8%、10%,基于明胶和普鲁兰的总干质量)对膜理化性质及抗氧化、抗菌性能的影响。傅里叶红外光谱和扫描电子显微镜结果表明：茶多酚与普鲁兰多糖和明胶之间存在分子间相互作用,尤其当茶多酚质量分数为6%时,膜结构更加致密。理化实验结果表明：随着茶多酚质量分数的增加,复合膜的抗拉强度和断裂伸长率均先增大后减小,水蒸气透过性先减小后增大,紫外线阻隔性能增强,膜变得更暗黄;而茶多酚的添加没有显著提高复合膜的热性能。此外,复合膜对DPPH自由基的清除率最高达87.44%,对大肠杆菌和金黄色葡萄球菌的最大抑制率分别为95.73%和85.22%。同时,复合膜能实现茶多酚的缓慢释放。茶多酚-普鲁兰-明胶复合膜的制备旨在为良好生物活性包装膜的开发提供有益参考。     

超声处理对芸豆蛋白理化性质及抗氧化能力的影响

本试验以脱脂芸豆蛋白为原料,利用溶解度、乳化性以及总抗氧化能力等指标分析不同超声条件对芸豆蛋白理化性质及抗氧化能力的影响。结果表明:与未处理组相比,当超声时间20 min、功率400 W时,芸豆蛋白的水解度与溶解度达到最大值,分别由3.34%增加至20.10%,56.83%增加至79.63%;超声处理后芸豆蛋白起泡性及起泡稳定性显著增强（P<0.05）,当超声时间10 min、功率400 W时分别达到最大值162.81%、72.94%;与未处理组相比,当超声时间10 min、功率400 W时乳化性最佳,增加了2.82 m2/g,超声功率不变,时间延长至20 min乳化稳定性最强,增加了18.95%;超声处理使芸豆蛋白的游离巯基含量显著提高（P<0.05）,二硫键含量显著减少（P<0.05）;总抗氧化能力在超声时间30 min,功率160 W时抗氧化能力最好（674.63 U/mL）,DPPH自由基清除能力与Fe离子还原能力在超声时间10 min、功率400 W时达到最大值,分别提高了38.96%、17.84%。综上,超声处理能够显著改善芸豆蛋白理化性质,提高其抗氧化能力。     

九蒸九制对鸡头黄精理化性质及抗氧化性的影响

为了探究蒸制处理对鸡头黄精有效成分及代谢物种类和含量影响,采用低场核磁、苯酚-浓硫酸法、高效液相色谱-蒸发光散射检测法（HPLC-ELSD）和液相色谱-质谱技术（LC-MS）等对其中的水分分布、多糖含量、单糖组成和代谢产物等进行分析。结果表明,多次蒸制后,鸡头黄精结合水的含量、多糖含量逐渐降低,水提液pH值逐渐降低呈弱酸性达到4.07,还原糖、总酚、黄酮含量逐渐升高分别达到28.69%、10.02 mg/g和0.69%,抗氧化性逐渐增强,ABTS抗氧化能力在7制达到最高为0.73 mmol/L,较1制增加0.35 mmol/L,DPPH自由基清除率和FRAP值在8制达到最高分别为81.95%,1.97 mmol/L,较1制分别增加50.92%,1.72 mmol/L;同时蔗糖逐渐水解从18.53 mg/g到7.62 mg/g,葡萄糖和果糖含量提高,分别由1制0.00和11.30 mg/g,达到9制17.25和230.89 mg/g。选取一制与九制黄精进行代谢物差异分析,在正离子模式下共检测到1 310种代谢物,差异代谢物有176种（按其特性分为38类）,在负离子模式下共检测到1 841种代谢物,差异代谢物有148种（按其特性分为26类）。黄精经蒸制后有效成分差异性显著,对鸡头黄精炮制加工提供科学依据。     

荞麦清蛋白水解物理化性质及抗氧化性研究

本试验研究了木瓜蛋白酶作用下,不同酶解时间对荞麦清蛋白物化及抗氧化能力的影响,包括了对酶解产物多酚含量、表面疏水性的测定以及DPPH自由基清除能力和羟自由基清除能力。结果表明,酶解做用后,荞麦清蛋白的多酚含量及表面疏水性有很大程度的改变,另外,荞麦清蛋白具有良好的抗氧化能力,其DPPH自由基和羟自由基清除能力在蛋白浓度为1 mg/mL时分别可达到为60%及80%,接近抗氧化剂2,6-二叔丁基对苯酚(BHT)的抗氧化能力,而酶解产物的抗氧化能力有所降低。     

碱处理对鸡肉粉物化性质及加工特性的影响

本实验以鸡肉粉物化性质与加工特性为研究重点,对不同碱浓度（0．25％～1．00％）和不同温度（70～100~C）处理后的鸡肉蛋白,采用光学显微镜、质构分析仪、扫描电镜、x．衍射等现代仪器,分析检测其物理与化学特性变化。结果表明,鸡肉结构的破坏程度、鸡肉蛋白质的溶解性随碱浓度和温度的增加而增加;碱浓度和温度对鸡肉蛋白质构特性有显著影响（P≤0．05）;碱处理可导致鸡肉蛋白质非晶化现象发生。     

外源抑制物对风干肠风干过程中理化性质及安全品质的影响

为研究外源抑制物对风干肠在风干过程中理化性质和安全品质的影响,将实验室前期优选的复合抗氧化剂（combined antioxidant,CA）、复合香辛料（combined spice,CS）、发酵牛骨调味基料（fermented beef flavoring,FBF）以及FBF和CA以1∶1复配（FBFA）、CA和CS以1∶1复配（CSA）应用于风干肠加工过程中,测定风干1、3、6、9、12 d时样品水分含量、水分活度（water activity,aw）、红度值（a*）、亮度值（L*）、pH值、硫代巴比妥酸反应物（thiobarbituric acid resctive substances,TBARs）值、亚硝酸盐残留量以及风干6、12 d生物胺含量和风干12 d时N-亚硝胺（N-nitrosoamines,NAs）含量。结果表明：在风干肠风干过程中添加5 种外源抑制物,产品水分含量与对照组差异不显著,但aw降低（0.80～0.81）;亚硝酸盐残留量为3.77～5.65 mg/kg,产品品质和安全性均显著提高。通过比较5 组外源抑制物可知,FBFA更能增强风干肠的a*和L*,降低TBARs值和亚硝酸盐残留量,控制组胺和NAs的形成,对风干肠的色泽和安全品质等均具有较好的改善作用。此外,CSA可以较好地抑制组胺和酪胺的形成,控制脂肪氧化和阻断NAs的形成。FBFA和CSA对风干肠的品质和安全性均具有显著增效作用。     

酶法改性对马铃薯渣膳食纤维单糖组分及理化性质的影响

采用纤维素酶、木聚糖酶、纤维素-木聚糖复合酶分别对马铃薯渣膳食纤维进行改性,研究酶法改性对膳食纤维理化性质和单糖组分的影响。单糖测定结果表明,3种酶法改性后膳食纤维中均含有葡萄糖、半乳糖、半乳糖醛酸、阿拉伯糖、木糖5种单糖,但不同酶法改性膳食纤维各单糖含量有显著差异(p<0.05)。理化性质测定结果表明,不同酶法改性后膳食纤维的持水力、结合水力、溶解度强弱次序均为复合酶改性>木聚糖酶改性>纤维素酶改性;持油力和阳离子交换力的强弱次序均为复合酶改性>纤维素酶改性>木聚糖酶改性,复合酶改性后膳食纤维理化性质明显优于其他酶法改性。复合酶改性后膳食纤维持水力、持油力、结合水力、溶解度、阳离子交换力分别为6.29 g/g、2.89 g/g、5.99 g/g、32.28%、0.60 mL/g,与原膳食纤维相比较分别提高了115.22%、16.73%、27.18%、45.27%、173.18%。马铃薯渣膳食纤维改性前后均具有糖类特征官能团,在某些波长处出现相似吸收峰,吸收峰的强度和面积发生了改变。     

麦麸多糖理化特性与抗氧化性分析

采用超声波法提取麦麸粗多糖,研究其理化性质、总糖含量、清除自由基能力及抗氧化性等特性。实验结果表明,麦麸粗多糖含有淀粉和蛋白质的多糖,总糖质量分数达到42.48%,具有一定的清除羟自由基、超氧阴离子和亚硝酸根离子的能力,对鸡蛋卵黄和小鼠肝脏自发性脂质过氧化具有一定的抑制作用。     

Coffee Antioxidant Properties: Effects of Milk Addition and Processing Conditions

ABSTRACT: In the human diet, coffee is the major source of caffeoyl-quinic acids known as powerful antioxidants. The aim of this study was to assess the effect of usual coffee consumption, such as the addition of milk, and of processing conditions, such as spray-drying, on beverage antioxidant power and potential polyphenol bioavailability impairments. When 25% milk was added to coffee, up to 40% of coffee chlorogenic acid were found to be bound to dairy proteins, using an ultrafiltration technique. However, neither milk addition nor spray-drying had a significant effect on beverage antioxidant power, evaluated using 2,2-diphenyl-1-pycrylhydrazyl (DPPH), 2-2'-azobis (2-amidinopropane) dihydrochloride (AAPH), and total antioxidant capacity (TAC) tests. Moreover, these interactions tended to decrease during in vitro gastric and intestinal digestion, thus suggesting that interactions between chlorogenic acid and milk proteins in coffee and milk beverage may not have any significant effect on coffee antioxidant power before and after consumption.