玫瑰希腊式酸奶生产工艺研究

以玫瑰花浆、乳清蛋白和奶粉为原料,研究了玫瑰希腊式酸奶的工艺条件。通过单因素试验和正交试验,以感官评定为标准,研究玫瑰希腊式酸奶的最佳工艺条件。结果表明,在乳清蛋白添加量为0.9%,玫瑰花浆添加量为8%,菌种添加量为5%,发酵温度42℃,发酵时间为7 h,感官评分最高。玫瑰希腊式酸奶质地均匀,口感细腻,酸甜适中,具有独特玫瑰清香味和浓郁的乳香味,其理化指标和微生物指标均符合国家标准。     

奇亚籽营养成分分析及其饮料工艺优化

为开发奇亚籽的营养价值,对黑、白两种奇亚籽的营养成分进行测定,并将其应用在饮料中。采用国标的方法测定基本营养成分,利用氨基酸自动分析仪、气相色谱-质谱联用仪(Gas Chromatography-Mass Spectrometer,GC-MS)分别测定氨基酸及脂肪酸含量,通过单因素实验和响应面试验优化奇亚籽柠檬汁饮料工艺配方。结果表明:黑、白奇亚籽粗蛋白质、粗脂肪、膳食纤维含量分别为16.40%、28.32%、34.67%和29.10%、30.48%、26.65%;二者水分和灰分含量均低于10%。共检出16种氨基酸,黑、白奇亚籽中必需氨基酸含量分别为7.37和7.77 g/100 g,占氨基酸总量的32.92%、38.39%。以氨基酸评分、化学评分为标准,第一限制性氨基酸均为蛋氨酸+半胱氨酸。黑、白奇亚籽中多不饱和脂肪酸分别占脂肪酸总量的82.82%和84.89%,其中omega-3占63.18%~68.37%,具有较高的食用价值。饮料最佳工艺配方:浓缩柠檬汁添加量10%、麦芽糖醇添加量14%、结冷胶添加量0.15%、奇亚籽添加量3%和甜蜜素添加量0.02%。在此条件下,饮料感官评分为(88.5±0.71)分,可制得口感好、色泽明亮、体系稳定均一的奇亚籽柠檬汁饮料。综合分析奇亚籽作为一种新食品原料,其营养价值丰富,并通过优化饮料制作工艺,为其在饮料深加工领域提供理论依据。     

奇亚籽油的健康功效

奇亚籽是一种我国批准的新食品原料,因其含有极为丰富的多不饱和脂肪酸而受到保健食品市场的关注。奇亚籽油是以奇亚籽为原料开发的油脂产品,在全球各个国家均有生产和销售。现有研究证明,奇亚籽油具有预防心脑血管疾病、改善糖尿病、抑制肥胖等保健功效,是一种值得深入开发的油脂产品。对奇亚籽的种植及营养进行概述,主要从脂肪酸角度讨论了奇亚籽油的健康功效及原理与机制,旨在为以后关于奇亚籽油的研究提供方向及指导。     

奇亚籽油提取工艺优化及降血脂功能研究

运用单因素试验和响应面试验对超声波辅助石油醚提取奇亚籽油的最佳工艺进行优化。以液固比、超声功率、超声时间为单因素条件,以奇亚籽油得率为评价指标,确定各个因素的最佳水平,同时对奇亚籽油的降血脂功能进行研究。结果表明,奇亚籽油提取的最佳工艺条件为液固比15︰1 (mL/g)、超声时间64 min、超声功率320W。在此条件下,奇亚籽油得率为30.12%±0.19%。经体内降血脂动物试验可知,奇亚籽油能有效抑制高脂血症小鼠的TC、TG、LDL-C含量,升高HDL-C含量,表明奇亚籽油具有一定降血脂功能。该研究为奇亚籽油作用机理的深入研究奠定基础。     

奇亚籽蛋白酶解制备抗氧化肽的工艺优化

以奇亚籽粗蛋白为原料,酶解法制备抗氧化肽并通过响应面法优化工艺。同时以1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl,DPPH)自由基和羟基自由基清除率为指标,通过单因素试验,筛选最佳酶并考察加酶量、pH值、时间、温度等对产物抗氧化能力的影响。在单因素试验基础上,通过响应面分析法对酶解工艺进一步优化,同时建立酶解工艺的二次项数学模型并验证其可靠性。结果表明:中性蛋白酶为最适酶,酶解最佳工艺为:加酶量3170 U/g,pH 6.9,酶解时间4.9 h,酶解温度50℃,此时DPPH自由基和羟基自由基清除率分别为54.90%、41.03%,与理论值无显著差异,回归模型较可靠,抗氧化能力(oxygen radical absorbance capacity,ORAC)值为(0.53±0.03)μmol TE/mg,表明奇亚籽抗氧化肽具有良好的抗氧化活性。     

奇亚籽胶提取工艺优化及其理化性质

以奇亚籽为原材料,利用单因素和响应面试验对奇亚籽胶的提取工艺进行优化筛选。结果表明,最佳的提取工艺条件为料液比1∶45（g/mL）、浸提温度90 ℃、pH8.2。对奇亚籽胶理化性质的研究结果表明,奇亚籽胶具有良好的理化性能,其优异的持水/油、乳化、起泡等性质使其在肉制品、烘焙产品、乳制品等领域的应用前景较广。     

奇亚籽油脂肪酸乙酯的制备工艺研究

以奇亚籽油为原料,采用碱催化法制备奇亚籽油脂肪酸乙酯。对比甲醇钠、乙醇钠和氢氧化钠的催化效果,并通过单因素实验和正交实验优化奇亚籽油脂肪酸乙酯制备的工艺参数。结果表明：采用氢氧化钠为催化剂,乙酯含量和得率均最高;当酯交换温度为80 ℃、酯交换时间为1.5 h、醇油摩尔比为9∶ 1、氢氧化钠用量为油质量的0.6%时,奇亚籽油脂肪酸乙酯含量可达到89.01%。     

奇亚籽提取物体外抗氧化活性研究

奇亚籽是唇形科植物芡欧鼠尾草的种子,已被证实具有多种健康促进作用。文中评价了白奇亚籽和黑奇亚籽的体外抗氧化活性并测定了其总多酚和总黄酮含量。结果表明:2种奇亚籽提取物均能够以浓度依赖的方式清除DPPH·和ABTS~+·,白奇亚籽提取物对DPPH·和ABTS~+·的清除能力显著高于黑奇亚籽提取物;白色和黑色奇亚籽提取物的FeSO_4·7H_2O当量分别为(41.48+2.84)μmol/g和(29.70±2.43)μmol/g;同时,2种奇亚籽提取物均能显著抑制亚油酸自由基引起的β-胡萝卜素漂白。此外,2种奇亚籽提取物均能够有效抑制自由基诱导的亚油酸过氧化和牛血清白蛋白氧化降解。白奇亚籽和黑奇亚籽中总多酚含量分别为(3.40±0.09)mg CAE/g和(2.97±0.07)mg CAE/g,总黄酮含量分别为(1.24±0.06)RE mg/g和(1.07±0.08)RE mg/g。     

奇亚籽油的研究进展

奇亚籽油含有丰富的多不饱和脂肪酸(PUFAs),其中亚麻酸含量达60%以上,被认为是ω-3多不饱和脂肪酸的良好来源,具有抗增殖和促凋亡作用、免疫刺激剂作用、体外抗氧化和抗高血压作用以及调节血脂和肝酶等功效,食用奇亚籽油对于维持正常的生理和脑功能具有重要的意义。从奇亚籽油的提取方法及脂肪酸组成、理化性质和生物活性等方面,综述了近年来国内外有关奇亚籽油的研究报道,旨在为奇亚籽油的开发利用提供参考,并对其今后的研究重点进行展望。     

一种新型油料作物——奇亚籽北大核心CSCD

为了更好地开发、利用奇亚籽资源,主要从奇亚籽的生物学性状、物候学特性及生长习性、种植分布及育种情况、营养成分、奇亚籽油的脂肪酸组成及活性物质,以及其在食品、保健品和化妆品行业中的应用研究进展进行综述。奇亚籽具有丰富的营养成分及富含不饱和脂肪酸的特性,作为一种新型食品原料和新型油料作物,其在食品、保健品等行业具有广阔的发展前景。     

Effects of seasonal variations on the quality of set yogurt,stirred yogurt,and Greek-style yogurt

We studied the effects of seasonal variations on the quality of stirred yogurt, set yogurt, and Greek-style yogurt over 2 milking seasons in New Zealand. Correlations between the properties of the yogurts, the characteristics of the milk, and the acid gelation properties induced by glucono-δ-lactone, reported in our previous works, were also explored. Set yogurt and Greek-style yogurt from the early season had the highest firmness over the seasons. The yogurt firmness correlated with the gel strength of glucono-δ-lactone-induced acid gels, indicating that the latter could, to some extent, predict the seasonal variations in the firmness of set yogurt. The correlation studies highlighted the potentially important role of the glycosylation of κ-casein in the seasonal variations in the yogurt structures. Yogurt made from mid-season milk had the lowest water-holding capacity, which may have played a part in lowering its firmness and viscosity. Late-season stirred yogurt displayed the strongest resistance to shear-induced thinning, which might arise from the unique viscoelastic properties of late-season yogurt gels.     

Use of micellar casein concentrate for Greek-style yogurt manufacturing: Effects on processing and product properties

The objective of this work was to develop and optimize an alternative make process for Greek-style yogurt (GSY), in which the desired level of protein was reached by fortification with micellar casein concentrate (MCC) obtained from milk by microfiltration. Two MCC preparations with 58 and 88% total protein (MCC-58 and MCC-88) were used to fortify yogurt milk to 9.80% (wt/wt) protein. Strained GSY of similar protein content was used as the control. Yogurt milk bases were inoculated with 0.02% (wt/wt) or 0.04% (wt/wt) direct vat set starter culture and fermented until pH 4.5. The acidification rate was faster for the MCC-fortified GSY than for the control, regardless of the inoculation level, which was attributed to the higher nonprotein nitrogen content in the MCC-fortified milk. Steady shear rate rheological analysis indicated a shear-thinning behavior for all GSY samples, which fitted well with the power law model. Dynamic rheological analysis at 5°C showed a weak frequency dependency of the elastic modulus (G′) and viscous modulus (G″) for all GSY samples, with G′ > G″, indicating a weak gel structure. Differences in the magnitude of viscoelastic parameters between the 2 types of GSY were found, with G′ of MCC-fortified GSY < G′ of control, indicating a different extent ofprotein interactionsin the 2 types of yogurt. Differences were also noticed in water-holding capacity, which was lower for the MCC-fortified GSY compared with the control, attributed to lower serum protein content in the former. Despite some differences in the physicochemical characteristics of the final product compared with GSY manufactured by straining, the alternative process developed here is a feasible alternative to the traditional GSY make process, with environmental and possibly financial benefits to the dairy industry.     

酸乳发酵工艺的优化

在单因素试验的基础上,通过正交实验对酸乳发酵工艺进行优化,得最佳工艺为保加利亚乳杆菌与嗜热链球菌质量比为1∶1,接种量为3g/100g,发酵温度为43℃,乳固体含量为10 g/100 g。     

Short communication: Chia seed extract enhances physiochemical and antioxidant properties of yogurt

Yogurt is a healthy dairy food fermented by lactic acid bacteria (LAB). Because consumers demand healthier and more nutritious yogurt, numerous substances have been used to supplement yogurt. Chia seed has been reported to contain abundant phenolic compounds, dietary fiber, and n-3 fatty acids and therefore is a potential functional food additive. The aim of this study was to investigate the influence of chia seed extracts on the physicochemical and bioactive properties of set-type yogurt. Yogurt was fortified with chia seed water extract (CSWE) or chia seed ethanol extract (CSEE) at 0.05 or 0.1% (vol/vol). Results showed that supplementation with CSWE or CSEE significantly accelerated the fermentation rate and growth of LAB. Both CSWE and CSEE improved the viscosity, syneresis, and water-holding capacity of yogurt. The radical scavenging activity of yogurt was increased with both extracts, and the 0.1% CSEE yogurt exhibited the highest radical scavenging activity. Furthermore, 0.1% CSEE yogurt significantly inhibited lipopolysaccharide-induced production of hydrogen peroxide in human colon cells. Addition of chia seed extract improves the growth of LAB, the physiochemical properties, and the health-beneficial effects of set-type yogurt.     

奇亚籽油微胶囊的制备及表征

为提高奇亚籽油的稳定性,对其进行微胶囊化。以包埋率为评价指标对冷冻干燥制备奇亚籽油微胶囊的工艺进行优化,利用激光粒度仪、扫描电镜、红外光谱仪和差示扫描量热仪(differential scanning calorimetry,DSC)等表征微胶囊性状。结果表明,微胶囊的最佳制备工艺为:壁材比(酪蛋白酸钠∶D-乳糖-水合物)1.1∶1(质量比)、固形物浓度31.32%、壁芯比2.34∶1(质量比),包埋率达到90.65%。所得微胶囊产品含有芯材、壁材的特征峰,表明形成奇亚籽油微胶囊的包埋结构。制得的奇亚籽油微胶囊呈不规则的几何形状和紧凑的结构,大小均匀,流动性较好,粉末表面光滑,黏度小,稳定性良好,可满足一般食品加工条件,为奇亚籽油微胶囊在食品工业中的应用提供参考。     

高蛋白饮用型长保质期酸奶产品的研究

对高蛋白酸奶的加工方法及稳定体系和工艺进行了研究。通过添加乳清蛋白和膜浓缩2种不同方式提高产品蛋白含量;通过稳定性观察、感官测试和稳定性检测综合评价产品稳定体系。试验结果表明,采用反渗透膜过滤方式提高蛋白含量,杀菌温度118℃,发酵温度43℃;稳定体系琼脂添加量0.05%,果胶添加量0.19%,此条件下产品的感官、持水性和稳定性最佳。     

Power ultrasound as a tool to improve the processability of protein-enriched fermented milk gels for Greek yogurt manufacture

One approach to avoid production of acid whey during the manufacture of high-protein yogurt and related products is to concentrate the milk before fermentation. However, the resultant gels are firm so that stirring in the tank and further processing are difficult on an industrial scale. We hypothesize that power ultrasound (US) during fermentation softens the gel because sound waves cause cavitation and strong shear forces in the fluid. Skim milk was standardized to different protein contents up to 12%, heated (85°C, 30 min), and acidified with thermophilic or mesophilic starter cultures. An excessive increase in gel firmness as a function of protein content was detected. In the next series of experiments, US was applied during fermentation. Milks (10% protein) were acidified at 43.5°C and sonicated from pH 5.8 to 5.1 with a sonotrode (20 kHz, 20 W). Immediately after fermentation, gels were agitated using a rheometer with a vane geometry. The maximum torque required to break the gel was reduced by 75% following US, and gel firmness was reduced by 80%. Gels were then processed into stirred yogurt and analyzed. Sonicated samples were smoother with fewer large aggregates. Confocal laser scanning microscopy images suggested a less cohesive structure and more compact microgel particles, resulting in reduced viscosity. We concluded that US is a promising tool to weaken the gel and facilitate further processing. This enables new approaches for the manufacture of Greek yogurt, particularly in regard to avoiding production of acid whey and developing products with novel textures.     

菱角-莲子酸奶的生产工艺研究

以菱角、莲子、牛奶为主要原料,采用乳酸菌发酵,通过正交试验确定出发酵工艺参数和酸奶的最佳配方。结果表明,该酸奶最佳配方为菱角汁15%,莲子汁2%,接种量为0.3%,蔗糖添加量为8%。在42℃发酵5.0 h,稳定剂为0.3%的蔗糖脂肪酸酯和1.2%的分子蒸馏单甘酯,此条件下得到的菱角-莲子发酵酸乳具有菱角和莲子特有的清香味道,且质地均匀,口感优良,营养丰富。     

豆豉糖蛋白在酸乳中的应用研究

通过添加0.2%豆豉糖蛋白于酸乳中,未添加糖蛋白组作为对照,研究比较豆豉糖蛋白酸乳与原味酸乳的抗氧化活性、流变特性、质构感官特性以及色泽（L*、a*、b*）变化。采用流变仪、质构仪、色差计等对其品质特性进行研究,以二苯代苦味基肼自由基（DPPH·）法、水杨酸法和Fe3+还原能力三种方法评价抗氧化活性。研究显示,添加豆豉糖蛋白对酸乳的品质特性等无显著影响。其清除DPPH自由基的IC50值为25.71mg/m L,比未添加组的30.67mg/m L有所降低;其清除羟基自由基IC50值为29.66mg/m L,比未添加组的42.75mg/m L有所降低;Fe3+还原能力在浓度为75mg/m L时,未添加组与添加糖蛋白组比较其吸光度值由0.29增加到0.33。故添加少量糖蛋白能够提高酸乳的抗氧化功能活性且对其食用品质无明显影响。