Sensory Characteristics of Milk Chocolate with Lactose from Spray-Dried Milk Powder

Dry whole-milk powders with 0-70% nominal lactose prepared by spray-drying alone (containing amorphous lactose) or combined with post-drying crystallization (containing crystalline lactose) were incorporated into milk chocolate to give 0-50% substitution of lactose for sucrose. No significant differences occurred in sweet, bitter, and thickness of melt (P > 0.10) based on milk powder preparation method or lactose concentration. As lactose increased, hardness and onset of melt increased regardless of milk powder preparation method; but, chocolates containing crystalline lactose were softer than those containing amorphous lactose. Higher chocolate, milk and caramel flavors were perceived in milk chocolates containing crystalline lactose. Graininess of milk chocolate increased at the highest level of added lactose.     

Water Plasticization and Crystallization of Lactose in Spray-dried Lactose/Protein Mixtures

ABSTRACT: Water plasticization led to depression of the glass transition causing significant changes in the physico-chemical and crystallization properties in storage of lactose and lactose/protein (3:1) mixtures. Glass transition (Tg) and crystallization temperatures (Tcr) were determined using differential scanning calorimetry. Whey protein isolate (WPI), albumin, and gelatin increased the Tg of dry powders; when Na-caseinate was used, a decrease was observed. In the presence of proteins and water, a decrease of Tg at aw ≤ 0.23 was observed. At aw ≤ 0.33, proteins increased the Tg In the anhydrous state, Tcr decreased in the presence of proteins possibly because of browning. WPI, Na-caseinate, albumin, and gelatin delayed lactose crystallization in humidified samples, with albumin and gelatin delaying it more than WPI at all storage humidities. Temperature difference between an observed instant crystallization and glass transition (Tcr to Tg) was larger for humidified samples containing proteins than for lactose. Various proteins and water affect crystallization behavior of amorphous lactose differently in spray-dried powders. This should be considered in evaluating sugar crystallization properties in food products including dairy powders.     

Flow Behavior of Milk Chocolate Melt and the Application to Coating Flow

ABSTRACT: The rheological properties of chocolate, especially shear viscosity and yield stress, are important control parameters for enrobing processes in confectionery manufacture. The rheological parameters of molten milk chocolate were measured at 42°C during steady pipe flow using a magnetic resonance imaging (MRI) viscometric method. The experimental method combines shear rate values obtained from an MR velocity image and shear stress values obtained from an independent pressure drop measurement. The experimental factors were emulsifier type and emulsifier level. The rheogram data were fit by the Casson model to yield the Casson yield stress and plastic viscosity. The Casson yield stress ranged from 1.9 to 15.0 Pa; the Casson viscosity ranged from 6.0 to 14.6 Pa s as a function of emulsifier content. The rheological parameters were incorporated into a drainage theory model to predict coating thicknesses in the enrobing process. The model was solved numerically and yielded good approximations to the experimental values that were between 1.1 to 2.7 mm.     

Physical and Sensory Properties of Milk Chocolate Formulated with Anhydrous Milk Fat Fractions

Maximum additions of milk fat that produced temperable milk chocolates were anhydrous milk fat (AMF), middle-melting fraction (MMF) or low-melting fraction (LMF) up to 40 wt % total fat, and high-melting fraction (HMF) up to 35%. The solid fat content (SFC), melting point, melting enthalpy, instrumental and sensory hardness of milk chocolates decreased with increasing milk fat addition. No differences in sensory attributes sweetness, milk powder, chocolate, butter flavor or thickness of melt were observed. Chocolate with 40% MMF or LMF had greater milk flavor than that with 12.2% HMF. Onset of melt correlated (r = 0.96) with melting enthalpy. No differences between types of milk fat (AMF, HMF, MMF, LMF) were observed for any textural attribute assessed.     

Water Sorption and Plasticization Behavior of Spray-dried Lactose/Protein Mixtures

ABSTRACT: Water sorption properties, effects of proteins on glass transition temperature, and time-dependent lactose crystallization of spray-dried lactose and lactose in lactose/WPI (3:1), lactose/Na-caseinate (3:1), lactose/albumin (3:1), and lactose/gelatin (3:1) mixtures were investigated. Brunauer-Emmett-Teller (BET) and Guggenheim-Anderson-de Boer (GAB) models were used to model water sorption. Lactose/protein mixtures sorbed high amounts of water at low relative vapor pressure (RVP) up to 23.1%. Above 23.1% RVP levels, water sorbed by pure lactose was higher, up to 44.1% RVP, except in the case of the lactose/gelatin mixture. Lactose/ gelatin also sorbed a high amount of water at 33.2% RVP. Loss of sorbed water resulting from crystallization of amorphous lactose was observed. Crystallization of pure lactose and lactose crystallization in lactose/protein mixtures occurred at RVP ≥ 44.1% within 24 h. After crystallization at RVP ≥ 54.5%, water contents remained higher for lactose/protein mixtures than for pure lactose. The rate of lactose crystallization was less in all lactose/protein mixtures than was observed for pure lactose. WPI had the lowest effect on lactose crystallization. Crystallization occurred most slowly in lactose/gelatin mixtures. Both GAB and BET models fitted to water sorption data up to 0.441 a_w. It seems that different proteins interact with lactose differently. Water sorption and time-dependent lactose crystallization of lactose/protein mixtures have important consequences to processing and storage behavior of lactose-protein based products.     

低乳糖营养奶片的研制

本文主要研究探讨了低乳糖营养奶片的配方组成及其生产工艺条件等,同时探讨了奶片改良剂等辅助成分对生产过程及其产品的溶解性等物理特性的影响。实验研究结果表明,该产品具有营养丰富全面,口味香甜纯正及无褐变等特点,其乳糖的水解率高达70%以上,可以有效的预防人体乳糖不耐症状的发生。     

Light-Oxidized Flavor Development and Vitamin A Degradation in Chocolate Milk

Samples of several chocolate milk formulations were exposed to light to determine if the components masked and/or prevented light-oxidized flavors or prevented photodegradation of vitamin A. Chocolate flavor added either before or after light exposure masked light-oxidized flavor (p<0.05). Neither carrageenan nor chocolate color prevented development of light-oxidized flavor. Vitamin A degradation was reduced by the addition of carrageenan alone or in combination with chocolate dairy powder (chocolate flavor and color), chocolate color or chocolate flavor (p<0.05).     

Retention of Diacetyl in Milk during Spray-Drying and Storage

Spray-drying of milk in a Leaflash dryer was studied in relation to volatile aroma loss in drying and during storage of the powders. Diacetyl was used as the volatile model, and the contribution of the various milk constituents to retention was determined. Proteins retain more diacetyl than does lactose or fat. Conditions leading to a powder with more amorphous lactose result in higher diacetyl loss during drying. The rate of diacetyl loss during storage depended on relative humidity and on the T — T_g parameter and was strongly enhanced by crystallization of amorphous lactose.     

蔗糖酯对类可可脂巧克力加工影响的研究

研究CTCBE及CB两种巧克力中添加蔗糖酯对其调温及抗霜性的影响。在两种巧克力(含磷脂0.5％)DSC、XRD研究的基础上，采用具有可比性的粘度法、耐促霜组合实验方法进一步测定两种巧克力中添加蔗糖酯后在调温点的粘度变化规律、变稠时间及抗霜效果。结果表明添加蔗糖酯S-3对CTCBE巧克力具有明显减稠和延缓结晶效果；对CB巧克力的延缓结晶效果更好。还可以延缓CTCBE巧克力起霜花。添加0．2％效果最佳。     

低乳糖奶粉的研制

研究了低乳糖奶粉的制作,通过乳糖酶的添加量、乳糖酶的水解温度、水解时间及水解时的pH对乳糖水解率、牛乳中微生物的影响,确定了低乳糖奶粉的水解条件;并对工艺条件进行了讨论。     

低乳糖益生菌乳粉制备研究

本实验以全脂牛奶为原料,探究低乳糖高益生菌乳粉的制备工艺,考察水解温度、pH、时间和乳糖酶添加量对水解率的影响.同时通过海藻酸钠-大豆分离蛋白复配壁材微胶囊包埋益生菌,各自制备完成后分别真空冷冻干燥低乳糖牛乳和益生菌微胶囊,干燥结束将低乳糖乳粉与益生菌微胶囊粉按质量比7:1的比例混合制得低乳糖益生菌乳粉.结果表明,牛乳...     

Membrane Fractionation Processes for Removing 90% to 95% of the Lactose and Sodium from Skim Milk and for Preparing Lactose and Sodium‐Reduced Skim Milk

ABSTRACT: Pilot‐scale microfiltration (MF), microfiltration‐diafiltration (MDF), ultrafiltration (UF), ultrafiltration‐diafiltration (UDF), and nanofilration (NF) membrane fractionation processes were designed and evaluated for removing 90% to 95% of the lactose and sodium from skim milk. The study was designed to evaluate several membrane fractionation schemes as a function of: (1) membrane types with and without diafiltration; (2) fractionation process temperatures ranging from 17 to 45 °C; (3) sources of commercial drinking water used as diafiltrant; and (4) final mass concentration ratios (MCR) ranging from about 2 to 5. MF and MDF membranes provided highest flux values, but were unsatisfactory because they failed to retain all of the whey proteins. UDF fractionation processes removed more than 90% to 95% of the lactose and sodium from skim milk. NF permeate prepared from UDF cumulative permeate contained sodium and other mineral concentrations that would make them unsuitable for use as a diafiltrant for UDF applications. A method was devised for preparing simulated milk permeate (SMP) formulated with calcium, magnesium, and potassium hydroxides, and phosphoric and citric acids for use as UDF diafiltrant or for preparing lactose and sodium reduced skim milk (L‐RSM). MF retentates with MCR values of 4.7 to 5.0 exhibited extremely poor frozen storage stabilities of less than 1 wk at ?20 °C, whereas MCR 1.77 to 2.95 MDF and UDF retentates and skim milk control exhibited frozen storage stabilities of more than 16 wk. L‐RSM exhibited a whiter appearance and a lower viscosity than skim milk, lacked natural milk flavor, and exhibited a metallic off‐flavor.     

冷冻干燥草莓巧克力的研制

研究了草莓的冷冻干燥及巧克力涂衣方法的生产工艺,确定了冻干草莓的工艺参数及巧克力涂衣的两种方法的生产参数,其中以喷淋挂衣法为佳。     

渗透性K.lactis细胞内乳糖酶水解牛乳中乳糖的研究

应用填充床细胞反应器,以渗透性K．lactis细胞内乳糖酶连续催化牛乳中乳糖的水解。渗透性K．lactis细胞内乳糖酶的热失活遵循一级反应动力学,40℃时酶的半衰期为9．5h,表观米氏常数为0．39mmol/ml,最大反应速率Vmax为0．188mmol/min。在2．6cm×50cm填充床生物反应器上,渗透性K．lactis细胞内乳糖酶催化牛乳中乳糖水解的适宜体积流速为1．0ml/min,酶反应的适宜温度40℃,反应速率达到动态平衡后生成的葡萄糖的质量浓度为45．2mg/ml,牛乳中乳糖的水解率为91．3%。     

渗透性K.1actis细胞内乳糖酶水解牛乳中乳糖的研究

应用填充床细胞反应器，以渗透性K．1actis细胞内乳糖酶连续催化牛乳中乳糖的水解。渗透性K．1actis细胞内乳糖酶的热失活遵循一级反应动力学，40℃时酶的半衰期为9．5h，表观米氏常数为0．39mmol／ml，最大反应速率Vmax为0．188mmol／min。在2．6cm×50cm填充床生物反应器上，渗透性K．1actis细胞内乳糖酶催化牛乳中乳糖水解的适宜体积流速为1．Oml／min，酶反应的适宜温度40℃，反应速率达到动态平衡后生成的葡萄糖的质量浓度为45．2mg／ml，牛乳中乳糖的水解率为91．3％。     

基于不同乳糖浓度的乳蛋白浓缩物发酵特性研究

利用保加利亚乳杆菌和嗜热链球菌复合发酵剂对乳蛋白浓缩物(milk protein concentrate,MPC)进行发酵,研究了不同乳糖浓度下MPC的发酵特性。结果表明,乳糖浓度影响MPC发酵进入稳定期的时间与pH值,随着乳糖浓度的升高,MPC发酵物的最终pH值下降(pH值范围4.14～4.59);微流变学研究表明,随乳糖浓度升高,MPC发酵物的宏观黏性因子减小,而固液平衡值和流动性指数增大;质构特性研究表明,MPC发酵物的持水力随乳糖浓度升高而逐渐升高,胶着性、弹性则呈现先增大后减小的趋势,而硬度、黏力不受影响;气相色谱-质谱联用分析结果显示,酸类化合物和酮类化合物是MPC发酵物中的主要挥发性物质,随乳糖浓度的增加,酸类化合物含量减少,而2,3-丁二酮、3-羟基-2-丁酮等乳糖代谢物的含量增加。本研究结果旨在为进一步了解MPC的发酵特性并拓宽MPC在不同发酵乳制品中的应用提供基础数据。     

Extrinsic Attributes That Influence Parents’ Purchase of Chocolate Milk for Their Children

The consumption of milk is essential for children's heath; and flavored milk, especially chocolate milk, is often purchased to increase children's milk consumption. However, the sugar content of chocolate milk has raised health concerns. As such, it is important to understand chocolate milk extrinsic attributes that influence parents’ purchase decisions when they are purchasing chocolate milk for their children. The objective of this study was to determine the key extrinsic attributes for parents when they purchase chocolate milk for their children. An online survey with a conjoint analysis design, emotions questions, and Kano questionnaire that focused on chocolate milk was conducted targeting parents. Three hundred and twelve parents participated in the survey. Parents reported positive emotions including good, good natured, happy, loving, and satisfied when purchasing chocolate milk for their kids. Three segments of parents were identified with subtle but distinct differences in their key preferences for chocolate milk attributes for their children. Type of sweetener was the primary driver of choice for purchasing chocolate milk for children followed by fat content. Among sweetener types, natural noncaloric/nonnutritive sweeteners or sucrose were preferred over artificial sweeteners, and reduced fat was preferred over full fat or skim milk. Kano results revealed that reduced fat and sugar with an all natural label and added vitamins, minerals, and protein were attractive to the majority of parents when purchasing chocolate milk for their kids.     

低乳糖芒果风味发酵乳制作工艺研究

以生牛乳、芒果泥为原料,通过试验对低乳糖芒果风味发酵乳产品配方及乳化稳定剂的复配方案进行了研究。结果表明:低乳糖芒果风味发酵乳最优配方为白砂糖8.0%、乳清蛋白粉1.0%、芒果泥5.0%、芒果香精0.04%、乳糖酶0.025%;产品最佳稳定剂为羟丙基二淀粉磷酸酯0.4%、明胶0.15%、琼脂0.1%。在该配方及稳定体组合条件下,可获得口感优良,风味合适,货架期质量稳定的低乳糖芒果风味发酵乳。     

酶法水解乳糖与热处理偶联对牛乳Maillard反应的影响

旨在探讨乳糖水解程度及热处理方法与Maillard反应的关系,鲜牛乳用中性乳糖酶处理获得不同水解程度的低乳糖牛乳,然后对牛乳进行不同的热处理,处理后的样本进行Maillard反应程度评价。采用葡萄糖氧化酶法测定不同水解时间的牛乳中葡萄糖质量浓度和乳糖水解率,用高效液相色谱法和紫外分光光度法分别测定水解后牛乳经不同热处理后的糠氨酸和5-羟甲基糠醛(5-hydroxymethylfurfural,5-HMF)含量及牛乳褐变程度的OD值。结果表明,随着乳糖水解时间的延长,牛乳中的葡萄糖含量呈增加的趋势,葡萄糖质量浓度从0.00 mg/100 m L增加到1 721.33 mg/100 m L,但增加趋势逐渐变缓;乳糖水解率从0%增加到70.33%,水解时间2.0 h后的牛乳水解率达到了50%以上。糠氨酸含量呈上升的趋势(P0.05),水解时间在3.0 h以上并经75℃、30 min热处理的牛乳,糠氨酸含量超过了190 mg/100 g pro;水解时间为0.5 h及以上并经75℃、15 s热处理的牛乳,糠氨酸含量超过了12 mg/100 g pro。生鲜牛乳和水解后经75℃、30 min热处理的牛乳,均未检测到5-HMF,水解后经75℃、15 s热处理的牛乳,随乳糖水解时间的延长,牛乳中5-HMF含量增加显著(P0.05)。牛乳的褐变程度随乳糖水解时间显著增加(P0.05),且乳糖酶水解后75℃、30 min热处理的牛乳的褐变程度明显高于75℃、15 s热处理的牛乳。本研究结果说明,乳糖经过酶水解后的牛乳,长时间热处理会加重乳Maillard反应,影响乳的蛋白质品质。