Ice cream structural elements that affect melting rate and hardness

Statistical models were developed to reveal which structural elements of ice cream affect melting rate and hardness. Ice creams were frozen in a batch freezer with three types of sweetener, three levels of the emulsifier polysorbate 80, and two different draw temperatures to produce ice creams with a range of microstructures. Ice cream mixes were analyzed for viscosity, and finished ice creams were analyzed for air cell and ice crystal size, overrun, and fat destabilization. The ice phase volume of each ice cream were calculated based on the freezing point of the mix. Melting rate and hardness of each hardened ice cream was measured and correlated with the structural attributes by using analysis of variance and multiple linear regression. Fat destabilization, ice crystal size, and the consistency coefficient of the mix were found to affect the melting rate of ice cream, whereas hardness was influenced by ice phase volume, ice crystal size, overrun, fat destabilization, and the rheological properties of the mix.     

Freezing and Ice Recrystallization Properties of Sucrose Solutions Containing Ice Structuring Proteins from Cold-Acclimated Winter Wheat Grass Extract

ABSTRACT: The freezing properties of sucrose solutions containing ice structuring proteins (ISPs) from cold-acclimated winter wheat grass extract (AWWE) were evaluated. Neither significant ice nucleation nor thermal hysteresis activity in unpurified AWWE were detected ( P > 0.05). Ice recrystallization in sucrose solutions was assessed by bright field microscopy. Ice crystal growth was significantly reduced with the addition of more than 0.05% total protein from AWWE in 23% sucrose solutions frozen under static conditions and temperature cycled under long periods of time (60 min). Ice recrystallization inhibition was not evident when the samples were temperature cycled for shorter periods of time (10 min), indicating that an adsorption time may be required for the ISPs to be significantly active. The ice recrystallization was reduced with the increased on ISP concentration until reaching a plateau after adding 0.13% total protein from AWWE, representing a surface coverage of 9 mg protein/m² ice (assuming 100% adsorption). The reduction of ice crystal growth was as high as 74% compared with the control. This ice recrystallization inhibition offers significant opportunity for the use of ISPs from AWWE in frozen foods.     

Ice Cream: Foam Formation and Stabilization—A Review

Ice cream has been studied from ingredients to process conditions, ice crystal formation to ice crystal growth, and ingredient selection to eating quality. One of the key aspects of ice cream is air cells, as formation and acceptance of ice cream rely on foam production and stabilization. Air cells in ice cream provide a unique structure that governs many of this product's keeping and eating qualities. The air cells are dependent upon ice cream mix composition (fat, protein, and surface active ingredients) as well as processing conditions (freezer shear force, hardening time, and storage temperatures). Optical, low-temperature scanning electron microscopy and transmission electron microscopy are applied to observe the morphology and size of air cells in ice cream. Air cells are crucial in forming the product and for eating quality and enjoyment.     

Ice recrystallization inhibition in ice cream as affected by ice structuring proteins from winter wheat grass

Ice recrystallization in quiescently frozen sucrose solutions that contained some of the ingredients commonly found in ice cream and in ice cream manufactured under commercial conditions, with or without ice structuring proteins (ISP) from cold-acclimated winter wheat grass extract (AWWE), was assessed by bright field microscopy. In sucrose solutions, critical differences in moisture content, viscosity, ionic strength, and other properties derived from the presence of other ingredients (skim milk powder, corn syrup solids, locust bean gum) caused a reduction in ice crystal growth. Significant ISP activity in retarding ice crystal growth was observed in all solutions (44% for the most complex mix) containing 0.13% total protein from AWWE. In heat-shocked ice cream, ice recrystallization rates were significantly reduced 40 and 46% with the addition of 0.0025 and 0.0037% total protein from AWWE. The ISP activity in ice cream was not hindered by its inclusion in mix prior to pasteurization. A synergistic effect between ISP and stabilizer was observed, as ISP activity was reduced in the absence of stabilizer in ice cream formulations. A remarkably smoother texture for ice creams containing ISP after heat-shock storage was evident by sensory evaluation. The efficiency of ISP from AWWE in controlling ice crystal growth in ice cream has been demonstrated.     

影响冰淇淋融化速率的质构因素

应用统计学模型研究了影响冰淇淋融化速率的质构因素。样品配方中采用3种甜味剂和3个水平的蔗糖酯。测定的因素包括凝冻前浆料的黏度,成品冰淇淋的各项TPA质构参数以及样品的膨胀率。由多元线性回归方程得出冰淇淋的黏附性、浆料的黏度、成品的膨胀率等因素对融化率的影响较大。     

Effect of trehalose on the glass transition and ice crystal growth in ice cream

The effects of trehalose and sucrose on the rate of ice crystal growth in ice cream during accelerated shelf‐life were compared. Experimental and theoretical freezing curves were shown to be in good agreement. Glass transition temperatures (T_g) of maximally freeze concentrated trehalose and sucrose solutions (40% w/w) were found to be ?39.5 °C and ?47 °C respectively. For ice cream mixes, the T_g value increased from ?46.4 °C for the 100% sucrose‐based mix to ?42.0 °C for the 100% trehalose sweetened ice cream. However, no differences in viscosity, nucleation rate or inhibition of ice crystal growth were observed with increasing trehalose concentration in ice cream.     

结晶原理和冰淇淋中的结晶现象

阐述了结晶原理在冰淇淋凝冻中的应用,详细叙述了结晶的目的和方法,晶核的形成原理,结晶体的成长,多晶现象,以及冰淇淋中的结晶现象.     

The Effects of Fat Structures and Ice Cream Mix Viscosity on Physical and Sensory Properties of Ice Cream

The purpose of this work was to investigate iciness perception and other sensory textural attributes of ice cream due to ice and fat structures and mix viscosity. Two studies were carried out varying processing conditions and mix formulation. In the 1st study, ice creams were collected at ?3, ?5, and ?7.5 °C draw temperatures. These ice creams contained 0%, 0.1%, or 0.2% emulsifier, an 80:20 blend of mono‐ and diglycerides: polysorbate 80. In the 2nd study, ice creams were collected at ?3 °C draw temperature and contained 0%, 0.2%, or 0.4% stabilizer, a blend of guar gum, locust bean gum, and carrageenan. Multiple linear regressions were used to determine relationships between ice crystal size, destabilized fat, and sensory iciness. In the ice and fat structure study, an inverse correlation was found between fat destabilization and sensory iciness. Ice creams with no difference in ice crystal size were perceived to be less icy with increasing amounts of destabilized fat. Destabilized fat correlated inversely with drip‐through rate and sensory greasiness. In the ice cream mix viscosity study, an inverse correlation was found between mix viscosity and sensory iciness. Ice creams with no difference in ice crystal size were perceived to be less icy when formulated with higher mix viscosity. A positive correlation was found between mix viscosity and sensory greasiness. These results indicate that fat structures and mix viscosity have significant effects on ice cream microstructure and sensory texture including the reduction of iciness perception.     

Development of Formulations and Processes to Incorporate Wax Oleogels in Ice Cream

The objective of this study was to investigate the influence of emulsifiers, waxes, fat concentration, and processing conditions on the application of wax oleogel to replace solid fat content and create optimal fat structure in ice cream. Ice creams with 10% or 15% fat were formulated with rice bran wax (RBW), candelilla wax (CDW), or carnauba wax (CBW) oleogels, containing 10% wax and 90% high‐oleic sunflower oil. The ice creams were produced using batch or continuous freezing processes. Transmission electron microscopy (TEM) and cryo‐scanning electron microscopy were used to evaluate the microstructure of ice cream and the ultrastructure of oleogel droplets in ice cream mixes. Among the wax oleogels, RBW oleogel had the ability to form and sustain structure in 15% fat ice creams when glycerol monooleate (GMO) was used as the emulsifier. TEM images revealed that the high degree of fat structuring observed in GMO samples was associated with the RBW crystal morphology within the fat droplet, which was characterized by the growth of crystals at the outer edge of the droplet. Continuous freezing improved fat structuring compared to batch freezing. RBW oleogels established better structure compared to CDW or CBW oleogels. These results demonstrate that RBW oleogel has the potential to develop fat structure in ice cream in the presence of GMO and sufficiently high concentrations of oleogel.     

Effect of Okra Cell Wall and Polysaccharide on Physical Properties and Stability of Ice Cream

Stabilizers are used in ice cream to increase mix viscosity, promote smooth texture, and improve frozen stability. In this study, the effects of varying concentrations (0.00%, 0.15%, 0.30%, and 0.45%) of okra cell wall (OKW) and its corresponding water‐soluble polysaccharide (OKP) on the physical characteristics of ice cream were determined. Ice cream mix viscosity was measured as well as overrun, meltdown, and consumer acceptability. Ice recrystallization was determined after ice cream was subjected to temperature cycling in the range of ?10 to ?20 °C for 10 cycles. Mix viscosity increased significantly as the concentrations of OKW and OKP increased. The addition of either OKW or OKP at 0.15% to 0.45% significantly improved the melting resistance of ice cream. OKW and OKP at 0.15% did not affect sensory perception score for flavor, texture, and overall liking of the ice cream. OKW and OKP (0.15%) reduced ice crystal growth to 107% and 87%, respectively, as compared to 132% for the control (0.00%). Thus, our results suggested the potential use of OKW and OKP at 0.15% as a stabilizer to control ice cream quality and retard ice recrystallization. OKP, however, at 0.15% exhibited greater effect on viscosity increase and on ice recrystallization inhibition than OKW.     

磷脂等乳化剂在花生冰淇淋中的应用

对磷脂等乳化剂在花生冰淇淋中的作用机理研究表明 ,磷脂与冰淇淋中蛋白质、油脂和水形成了一定强度的多分子吸附膜 ,从而使冰淇淋晶粒细小 ,质地光滑 ;磷脂不仅能提高花生冰淇淋的营养价值 ,而且乳化性还优于单甘酯 .正交实验获得了最佳乳化剂配方 :磷脂 0 .1 7% ,蔗糖酯0 .1 % ,单甘酯 0 .1 % .     

常用乳化剂对冰淇淋品质影响

对冰淇淋生产中常用的四种乳化剂单硬脂酸甘油酯、蔗糖脂肪酸酯、亲水性单甘油酯和三聚甘油单硬脂酸酯,采用单因素和正交实验方法进行比较,以冰淇淋成品膨胀率和抗融性两个指标作为评价标准,评价各自最终产品品质。     

Modeling of the effect of freezer conditions on the hardness of ice cream using response surface methodology

The effect of conventional continuous freezer parameters [mix flow (L/h), overrun (%), drawing temperature (°C), cylinder pressure (kPa), and dasher speed (rpm)] on the hardness of ice cream under varying measured temperatures (−5, −10, and −15°C) was investigated systematically using response surface methodology (central composite face-centered design), and the relationships were expressed as statistical models. The range (maximum and minimum values) of each freezer parameter was set according to the actual capability of the conventional freezer and applicability to the manufacturing process. Hardness was measured using a penetrometer. These models showed that overrun and drawing temperature had significant effects on hardness. The models can be used to optimize freezer conditions to make ice cream of the least possible hardness under the highest overrun (120%) and a drawing temperature of approximately −5.5°C (slightly warmer than the lowest drawing temperature of −6.5°C) within the range of this study. With reference to the structural elements of the ice cream, we suggest that the volume of overrun and ice crystal content, ice crystal size, and fat globule destabilization affect the hardness of ice cream. In addition, the combination of a simple instrumental parameter and response surface methodology allows us to show the relation between freezer conditions and one of the most important properties—hardness—visually and quantitatively on the practical level.     

Mechanisms of Ice Crystallization in Ice Cream Production

ABSTRACT: The smoothness and perceived quality of an ice cream depends in large part on the small size of ice crystals in the product. Understanding the mechanisms responsible for producing the disc‐shaped crystals found in ice cream will greatly aid manufacturers in predicting how processing and formulation changes will affect their product. Because ice cream mix is opaque, it has not yet been possible to observe ice crystallization in ice cream in situ. Studies to date, therefore, have used analogues or have related observed effects to a hypothesized mechanism. Still, some elements of the crystallization mechanism are well accepted. Because of the large supercooling at the freezer wall, ice nucleates there before being swept into the bulk of the freezer. In the bulk, heat and mass transfer cause some crystals to melt and others to grow. By the time the ice cream reaches the freezer exit, the ice crystals have become small, rounded discs.     

Modeling of the effect of freezer conditions on the principal constituent parameters of ice cream by using response surface methodology

A systematic analysis was carried out by using response surface methodology to create a quantitative model of the synergistic effects of conditions in a continuous freezer [mix flow rate (L/h), overrun (%), cylinder pressure (kPa), drawing temperature (°C), and dasher speed (rpm)] on the principal constituent parameters of ice cream [rate of fat destabilization (%), mean air cell diameter (μm), and mean ice crystal diameter (μm)]. A central composite face-centered design was used for this study. Thirty-one combinations of the 5 above-mentioned freezer conditions were designed (including replicates at the center point), and ice cream samples were manufactured and examined in a continuous freezer under the selected conditions. The responses were the 3 variables given above. A quadratic model was constructed, with the freezer conditions as the independent variables and the ice cream characteristics as the dependent variables. The coefficients of determination (R²) were greater than 0.9 for all 3 responses, but Q², the index used here for the capability of the model for predicting future observed values of the responses, was negative for both the mean ice crystal diameter and the mean air cell diameter. Therefore, pruned models were constructed by removing terms that had contributed little to the prediction in the original model and by refitting the regression model. It was demonstrated that these pruned models provided good fits to the data in terms of R², Q², and ANOVA. The effects of freezer conditions were expressed quantitatively in terms of the 3 responses. The drawing temperature (°C) was found to have a greater effect on ice cream characteristics than any of the other factors.     

冰淇淋成分抑制冰晶重结晶机制及研究技术

冰淇淋的品质受到冷冻过程中产生冰晶的大小和数量的影响,冰晶重结晶形成的大冰晶的形成对使冰淇淋的感官特性和质地产生负面影响 质地粗糙,冰晶感强,失去了冰淇淋应有的光滑细腻感。为了提高冰淇淋的品质和储存稳定性,本文深入阐述了冰晶重结晶的过程机理,首先总结了冰晶的三个过程,介绍了用于冰淇淋低温保护的成分,包括膳食纤维 、酶类物质、冰结构蛋白、膳食纤维等多糖类稳定剂等,提出多糖类稳定剂是目前抑制冰晶生长重结晶较为有效的方法,成本低廉。本文同时总结了国内外研究冰淇淋重结晶的常用技术,分析了抑制冰晶重结晶的措施及机制,包括低温光学显微技术、聚焦光束反射技术和低场核磁共振技术,其中,低温光学显微技术是最有效的技术手段,该技术和其它技术的结合为优化冰淇淋品质提供理论依据,以期为冰淇淋研发人员和生产厂家制作良好冻稳定性冰淇淋的提供理论依据和技术参考。     

乳化剂和稳定剂对软冰淇淋品质影响研究(英文)

本文对乳化剂和稳定剂对软冰淇淋品质的影响进行了研究。重点考察了软冰淇淋的硬度、抗溶性以及膨化率三个指标,研究结果表明,乳化剂的影响变化具有双重性,1.2%用量是最佳比例;稳定剂对抗溶性的影响具有正相关性,随着稳定剂用量增加,抗溶性提高;但是稳定剂对膨化率的影响呈现双重性,0.8%的用量为最佳比例,用量小于0.8%或者多于0.8%均减低膨化率。     

The Potential Application of Rice Bran Wax Oleogel to Replace Solid Fat and Enhance Unsaturated Fat Content in Ice Cream

The development of structure in ice cream, characterized by its smooth texture and resistance to collapse during melting, depends, in part, on the presence of solid fat during the whipping and freezing steps. The objective of this study was to investigate the potential application of 10% rice bran wax (RBW) oleogel, comprised 90% high‐oleic sunflower oil and 10% RBW, to replace solid fat in ice cream. A commercial blend of 80% saturated mono‐ and diglycerides and 20% polysorbate 80 was used as the emulsifier. Standard ice cream measurements, cryo‐scanning electron microscopy (cryo‐SEM), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM) were used to evaluate the formation of structure in ice cream. RBW oleogel produced higher levels of overrun when compared to a liquid oil ice cream sample, creating a lighter sample with good texture and appearance. However, those results were not associated with higher meltdown resistance. Microscopy revealed larger aggregation of RBW oleogel fat droplets at the air cell interface and distortion of the shape of air cells and fat droplets. Although the RBW oleogel did not develop sufficient structure in ice cream to maintain shape during meltdown when a mono‐ and diglycerides and polysorbate 80 blend was used as the emulsifier, micro‐ and ultrastructure investigations suggested that RBW oleogel did induce formation of a fat globule network in ice cream, suggesting that further optimization could lead to an alternative to saturated fat sources for ice cream applications.     

酶改性大豆分离蛋白在冰淇淋生产中的应用

探讨转谷氨酰胺酶改性大豆分离蛋白的乳化特性及其在冰淇淋生产中的应用。确定改性大豆分离蛋白冰淇淋的配方为：白砂糖12%,奶粉8%,奶油3%,改性大豆分离蛋白3%,CMC 0.1%,单甘酯0.1%,明胶0.2%。由此制得的冰淇淋膨胀率、融化率和感官指标均比较理想。较普通冰淇淋相比,减少了奶粉、乳化剂和稳定剂的用量,提高了冰淇淋的营养价值,降低了生产成本。     

Evaluation of Sucrose Esters in Ice Cream

Sucrose esters of varying hydrophilic-lipophilic balance (HLB) values were added to standard ice cream mixes at 0.15 or 0.25%, and compared with ice creams containing either a commercially available or no emulsifier. Resulting viscosities and overrun patterns were similar, but surface tensions decreased with increasing HLB and concentration. The addition of sucrose esters at 0.25% tended to prevent clumping out of fat particles. Sucrose ester-containing samples melted in a normal manner, and only texture differences were detectable among samples, with the ester-containing samples rated higher than the control or reference samples initially and similar to the reference after storage.