The effect of starter culture and annatto on the flavor and functionality of whey protein concentrate

The flavor of whey protein can carry over into ingredient applications and negatively influence consumer acceptance. Understanding sources of flavors in whey protein is crucial to minimize flavor. The objective of this study was to evaluate the effect of annatto color and starter culture on the flavor and functionality of whey protein concentrate (WPC). Cheddar cheese whey with and without annatto (15 mL of annatto/454 kg of milk, annatto with 3% wt/vol norbixin content) was manufactured using a mesophilic lactic starter culture or by addition of lactic acid and rennet (rennet set). Pasteurized fat-separated whey was then ultrafiltered and spray dried into WPC. The experiment was replicated 4 times. Flavor of liquid wheys and WPC were evaluated by sensory and instrumental volatile analyses. In addition to flavor evaluations on WPC, color analysis (Hunter Lab and norbixin extraction) and functionality tests (solubility and heat stability) also were performed. Both main effects (annatto, starter) and interactions were investigated. No differences in sensory properties or functionality were observed among WPC. Lipid oxidation compounds were higher in WPC manufactured from whey with starter culture compared with WPC from rennet-set whey. The WPC with annatto had higher concentrations of p-xylene, diacetyl, pentanal, and decanal compared with WPC without annatto. Interactions were observed between starter and annatto for hexanal, suggesting that annatto may have an antioxidant effect when present in whey made with starter culture. Results suggest that annatto has a no effect on whey protein flavor, but that the starter culture has a large influence on the oxidative stability of whey.     

发酵剂对熏马肠挥发性风味化合物的影响

通过顶空固相微萃取-气相色谱-质谱联用技术(HS-SPME-GC-MS)测定熏马肠中的挥发性风味物质。从5个不同样品中共鉴定出106种风味物质,包括烃类、醇类、酯类、酸类、醛类、酮类、酚类、呋喃类、含氮类等化合物。其中烃类、醇类、酸类、酮类、酚类化合物含量较高,空白组和发酵剂组熏马肠中挥发性风味化合物的种类和含量都存在着一定的差别。     

The effect of bleaching agent on the flavor of liquid whey and whey protein concentrate

The increasing use and demand for whey protein as an ingredient requires a bland-tasting, neutral-colored final product. The bleaching of colored Cheddar whey is necessary to achieve this goal. Currently, hydrogen peroxide (HP) and benzoyl peroxide (BPO) are utilized for bleaching liquid whey before spray drying. There is no current information on the effect of the bleaching process on the flavor of spray-dried whey protein concentrate (WPC). The objective of this study was to characterize the effect of bleaching on the flavor of liquid and spray-dried Cheddar whey. Cheddar cheeses colored with water-soluble annatto were manufactured in duplicate. Four bleaching treatments (HP, 250 and 500 mg/kg and BPO, 10 and 20 mg/kg) were applied to liquid whey for 1.5 h at 60°C followed by cooling to 5°C. A control whey with no bleach was also evaluated. Flavor of the liquid wheys was evaluated by sensory and instrumental volatile analysis. One HP treatment and one BPO treatment were subsequently selected and incorporated into liquid whey along with an unbleached control that was processed into spray-dried WPC. These trials were conducted in triplicate. The WPC were evaluated by sensory and instrumental analyses as well as color and proximate analyses. The HP-bleached liquid whey and WPC contained higher concentrations of oxidation reaction products, including the compounds heptanal, hexanal, octanal, and nonanal, compared with unbleached or BPO-bleached liquid whey or WPC. The HP products were higher in overall oxidation products compared with BPO samples. The HP liquid whey and WPC were higher in fatty and cardboard flavors compared with the control or BPO samples. Hunter CIE Lab color values (L*, a*, b*) of WPC powders were distinct on all 3 color scale parameters, with HP-bleached WPC having the highest L* values. Hydrogen peroxide resulted in a whiter WPC and higher off-flavor intensities; however, there was no difference in norbixin recovery between HP and BPO. These results indicate that the bleaching of liquid whey may affect the flavor of WPC and that the type of bleaching agent used may affect WPC flavor.     

Influence of milk-clotting enzymes on acidification rate of natural whey starter culture

The aim of this work was to study the influence of milk-clotting enzymes on whey starter culture and hard cheesemaking. Four cheeses were prepared simultaneously per cheesemaking day, and the experiment repeated on eight consecutive days. Adult bovine rennet was used in the control cheeses, and three formulations of fermentation-produced chymosin (FPC) in the experimental cheeses. Whey cultures were obtained from the whey of the preceding cheeses, incubated individually for 24 h at 42°C. pH values of the control and experimental whey did not differ significantly before incubation, but after 24 h incubation the pH of the FPC whey was significantly higher than that of the control. Soluble nitrogen content in trichloroacetic acid 2% and 12% and in phosphotungstic acid 2.5% was significantly lower for all experimental whey samples than for control whey. This probably explains the decrease in the acidification rate of the whey cultures when bovine coagulant is replaced by FPC in hard cheesemaking.     

发酵乳酪乳清中风味物质的分析研究

采用顶空固相微萃技术(HS-SPME)对发酵乳酪乳清中挥发性风味物质进行提取,并利用气相色谱-质谱联用技术(GC-MS)对挥发性风味物质进行分离鉴定。共鉴定出30种化合物,其中酸类物质质量分数最高,占总量的19.85%;其次为酮类,占总量的12.55%。在发酵乳酪乳清中这些挥发性物质中酸类和酮类物质可能为其重要的风味特征物质。     

Effects of fructooligosaccharide and whey protein concentrate on the viability of starter culture in reduced-fat probiotic yogurt during storage

ABSTRACT:  Viability of yogurt starter cultures and Bifidobacterium animalis was assessed during 28 d storage in reduced-fat yogurts containing 1.5% milk fat supplemented with 1.5% fructooligosaccharide or whey protein concentrate. These properties were examined in comparison with control yogurts containing 1.5% and 3% milk fat and no supplement. Although fructooligosaccharide improved the viability of Streptococcus thermophilus , Lactobacillus delbrueckii subs. bulgaricus, and Bifidobacterium animalis , the highest growth was obtained when milk was supplemented with whey protein concentrate in reduced-fat yogurt ( P < 0.05). Supplementation with 1.5% whey protein concentrate in reduced-fat yogurt increased the viable counts of S. thermophilus , L. delbrueckii subs. bulgaricus, and B. animalis by 1 log cycle in the 1st week of storage when compared to control sample. Similar improvement in the growth of both yogurt bacteria and B. animalis was also obtained in the full-fat yogurt containing 3% milk fat and no supplement. Addition of whey protein concentrate also resulted in the highest content of lactic and acetic acids ( P < 0.05). A gradual increase was obtained in organic acid contents during the storage.     

Invited review: The effects of processing parameters on the flavor of whey protein ingredients

Whey protein ingredients are used in a wide variety of products and are added primarily for nutritional benefits or functionality, not for flavor. However, the processes used to further refine fluid whey produce and encourage development of off-flavors that carry through to the final product. From the milk source to spray drying, each step contributes to the oxidation of lipids, which negatively affects flavor. An understanding of the sources of these flavor constituents and volatile compounds, as well as how they are formed during processing and handling, are important to eliminate or reduce undesirable flavors and for understanding how to best incorporate these ingredients into high-quality finished products.     

An economic evaluation of freeze-dried kefir starter culture production using whey

An economic study is presented in which industrial-scale production of freeze-dried kefir starter culture is discussed based on results on a laboratory scale. Industrial scale-up was based on a 3-step process using 3 bioreactors of 100, 3,000, and 30,000 L for 300 kg of freeze-dried culture/d of plant capacity. The major cost component of the total investment was the freeze-drying machinery, which consisted of 57% of the total investment. Production cost was reduced from €15.4/kg ($18.5/kg) to ∉2.9/kg ($3.5/kg) when the production capacity was increased from 30 to 900 kg/d. An economic analysis revealed a 3.5-fold increase in production cost compared with the corresponding production cost of the wet product, with an added value of up to ∉10.8 × 10⁹ ($13.0 × 10⁹) within the European Union.     

食用胶对鸭肉脯保藏期间挥发性风味物质变化的研究

随着保藏时间的延长鸭肉脯中的挥发性风味物质会逐渐挥发,造成鸭肉脯的风味减淡,影响鸭肉脯的品质,因此在加工的过程中需要采取措施以保持鸭肉脯在保藏过程中的挥发性风味物质的稳定性,以鸭肉为原料,研究了鸭肉脯在加工过程中添加黄原胶、卡拉胶、阿拉伯胶和魔芋胶对鸭肉脯保藏期间挥发性风味物质变化规律的影响。采用顶空固相微萃取技术和气相色谱质谱联用检测方(HS-SPEM-GC-MS)对鸭肉脯的挥发性风味物质进行萃取和检测,研究结果表明,添加食用胶后可以减缓鸭肉脯挥发性风味物质总含量的挥发速度,有效的保持了鸭肉脯的挥发性风味物质,同时添加食用胶对鸭肉脯中主要挥发性风味物质中的壬醛、草蒿脑等起到较好的保持作用,从而有利于延长鸭肉脯的保藏时间风味稳定性。     

8种典型成熟干酪挥发性风味差异性研究

利用固相微萃取—气相色谱质谱联用仪对8种典型天然成熟干酪的挥发性风味成分进行分析对比,并通过相对气味活力值阐明8种干酪之间风味的差异情况。结果表明:8种干酪共检测到74种挥发性物质,总体上呈现奶香味和果香味。切达干酪、高达干酪、帕玛森干酪、山羊乳干酪中异戊醛和乙酸乙酯赋予干酪果香味,十一酮和丁酸的修饰作用赋予干酪奶香味;艾达姆干酪中乙酸乙酯、辛酸乙酯和癸酸乙酯使得干酪果香味比较浓郁;布里干酪和蓝纹干酪果香味浓郁,但布里干酪果香味的来源是十一酮等酮类,同时这两种干酪中己酸、壬酮和苯乙醇赋予了臭味和哈喇味,布里干酪特有的1-辛醇也是造成不适气味的原因;安达文干酪中丁酸活力最强,在8种干酪中有最强的奶香味,同时己酸和2-壬酮的高活力赋予了干酪一些臭味和哈喇味。     

风味发酵液发酵面团挥发性风味物质及特征分析

目的:探究不同发酵时间下风味发酵液发酵面团的挥发性成分种类及含量。方法:采用顶空固相微萃取—气质联用法(HS-SPME-GC-MS)测定风味发酵液发酵12,24,36,48,72 h时,面团中的挥发性风味物质,并进行气味感官评定及pH值、总酸度(TAA)和面团流变学特性测定。结果:因不同发酵时间下产生的风味物质的种类和含量不等,8种气味(乳香、干酪味、花香味、水果甜香、酒味、麦芽味、青草香和酸味)的强弱度不同;面团pH值随发酵时间的延长逐渐降低,TTA则相反;面团的拉伸阻力、拉伸比及拉伸面积随发酵时间的延长整体呈先增后减趋势,延伸性则先下降后升高,表明适度发酵(发酵36 h)有利于面筋网络的形成和稳定。5个面团中共检出92种挥发性物质,其中醇类22种、酯类27种、醛类12种、酮类14种、烷烃类10种、酸类7种;发酵12,24,36,48,72 h的面团中分别检出27,43,38,41,37种挥发性风味成分,其中酸类及酯类物质含量随发酵时间的延长先升后降,均在48 h达到最高(分别为47.31%和20.96%),醛类、酮类及酸类物质含量则随发酵时间的延长逐渐降低。结论:不同发酵时间的挥发...     

干制方式对腌腊草鱼脂肪氧化和挥发性风味成分的影响

以不同干制方式制得的腌腊鱼（水分质量分数40%）为对象,基于菌落总数、酸价（acid value,AV）、过氧化值（peroxide value,POV）、硫代巴比妥酸（thiobarbituric acid,TBA）含量、总脂含量与总脂肪酸组成、挥发性风味物质、感官评分等指标,探讨了光照和温度对腌腊鱼风味品质的影响。结果显示：冷风避光组腌腊鱼样品的菌落总数最高,而热风光照组最低,分别为4.42、2.91（lg（CFU/g））。光照组腌腊鱼的脂质氧化指标均高于避光组,两者总脂含量无显著差异（P＞0.05）;热风组腌腊鱼的POV和TBA含量均显著高于冷风组（P＜0.05）,AV和总脂含量显著低于冷风组（P＜0.05）。多不饱和脂肪酸含量占腌腊鱼总脂肪酸含量的40%左右。无论是温度还是光照均对以二十二碳六烯酸为代表的n-3系多不饱和脂肪酸有显著影响（P＜0.05）。感官评价结果表明,冷风组和光照组腌腊鱼样品香气得分均显著高于热风组和避光组（P＜0.05）。本研究共从4 种腌腊鱼样品中检出了82 种挥发性物质,筛选确定了2-壬烯醛等14 种气味活性物质。相同温度下,光照组样品的气味活性值总和显著高于避光组（P＜0.05）,表明光照更有利于香气物质的生成。本研究可为腌腊鱼生产企业改善产品品质提供理论依据。     

浆水传统酿制过程中挥发性物质的动态变化

采用顶空固相微萃取结合气相色谱—质谱(HS—SPME—GC—MS)法分析浆水发酵过程挥发性物质的变化。结果表明:在发酵期间,共检出挥发性物质56种,主要为醇类(19种)、烃类(17种)、醛酮类(9种)、酯类(6种)、酸类(2种)。在发酵0,24,48,72,96h时发酵液中分别检出挥发性物质24,29,34,34,36种,其中共有成分12种。随发酵的进行,挥发性物质的种类逐渐增多且新增酯类物质。发酵前期,醇类、烃类的相对含量有所下降,酯类和酸类的相对含量显著上升,而在发酵后期,各类物质的相对含量变化较小。此外,在发酵阶段醛酮类物质的相对含量变化较小。其中双戊烯、乙酸乙酯、己醛、蒎烯、苯乙醇、正己醇、乙酸、乙酸丙酯对浆水风味的形成贡献较大。     

基于气相色谱-质谱联用技术分析酸浆豆腐加工过程中风味物质的变化

目的以酸浆豆腐为研究对象,结合气相色谱-质谱联用法(gas chromatography-mass spectrometry,GC-MS)优化酸浆豆腐不同加工阶段中挥发性风味物质的捕获方法,对酸浆豆腐的加工阶段进行分类。方法采用顶空-固相微萃取法(head space-solid phase microextraction,HS-SPME)结合GC-MS对风味物质进行检测,优化风味物质捕获方法,内标法进行定量,结合聚类分析对加工阶段进行分类。结果不同批次酸浆豆腐中风味物质变化具有较高的稳定性,酸浆豆腐加工过程中共鉴定出90种挥发性风味物质,制浆、煮浆、点浆、蹲脑10 min、蹲脑20 min和压制工序分别鉴定出27、25、32、39、45和22种挥发性风味物质,主要为醛类、酮类、醇类等风味物质。对加工过程中风味物质进行聚类分析发现:适当延长煮浆与蹲脑时间,可促进更多良好风味物质的形成。结论该方法操作简单,适合酸浆豆腐中风味物质的测定且稳定性好,在后续实验中可进一步对加工工艺进行调控。