Fat Coalescence Research Articles

Physicochemical property characterization, amino acid profiling and sensory evaluation of plant-based ice cream incorporated with soy, pea and milk proteins

This study examined the effects of incorporating milk protein concentrate (MPC), pea or soy proteins isolates (PPI and SPI) on the physicochemical, sensorial properties, and amino acid composition of ice creams containing 7% protein, in comparison to dairy ice cream as a reference. As protein ingredients, PPI exhibited higher water and oil holding capacity but lower surface hydrophobicity than SPI and MPC. Viscosity of the mixes were proportional to the firmness of ice cream, and both were highest with use of PPI. MPC ice cream had most similar physical and sensory properties to reference. PPI and SPI ice cream mixes showed higher extent of fat coalescence than MPC and reference. PPI and SPI conferred structural stability to ice cream with lower melting rate and better shape retention, and ability to delay ice recrystallization during temperature flocculation as compared with SMP and MPC. Confocal laser scanning microscope images indicated that higher extent of protein aggregation and more air cells were found in PPI ice cream. Sensory and amino acid profile results revealed that PPI and SPI ice creams were inferior in taste, texture, and essential amino acids like methionine. This study offers insights for the development of high protein frozen desserts.

Partial replacement of hydrogenated oil with beeswax oleogel in whipped cream: Effect on crystallization behavior and foam stability

Long-term consumption of hydrogenated palm kernel oil (HPKO) in whipped-frozen products has been linked to harmful health effects. The aim of this study was to investigate the use of beeswax oleogel as a partial replacement for HPKO in whipped cream. The effect of substitution rate on the lipid crystallization behavior, whipping characteristics, and foam stability of whipped creams was investigated. As the oleogel replaced 30–90% HPKO, the solid fat content decreased, and the growth pattern of the fat crystals shifted from two-dimensional disc-like to one-dimensional linear. Particle size distribution and microrheology analysis revealed that 30% or 60% oleogel substitution facilitated partial coalescence of fat, leading to in a higher elasticity index in emulsions. These results promoted overrun, firmness, and homogeneous bubbles in whipped creams. However, an oleogel substitution rate of 90% resulted in an excessively low overrun and collapse of foam structure. This study proposes an effective solution for constructing a frozen-aerated system that enhances fat partial coalescence and improves foam performance.

Fat coalescence and texture improvement of ice cream based on medium-chain triglyceride oleogel: Effect of gelator type

Academics and industry have invested in creating novel and functional ice creams to meet the growing demand for frozen foods that promote human health and nutrition. This study aimed to investigate the effect of medium-chain triglyceride (MCT) oleogels that prepared by three different gelators on the development of ice creams, as a complete substitute for hydrogenated palm kernel oil (HPKO). The results showed that both beeswax (BW) and phytosterol-oryzanol (PS-GO) caused the fat crystal to grow into three-dimensional spherulites, while ethylcellulose (EC) inhibited crystal size growth. Among the three types of oleogel-based ice creams, the BW sample exhibited the highest coalescence degree, followed by PS-GO and EC. The difference was due to variations in crystal growth and rigid crystal strength. Both BW and PS-GO oleogels improved the firmness of the ice creams by enhancing the formation of crystal network structures in the emulsions. The EC oleogel did not contribute to the overrun of the ice cream. The well-structured fat with partially coalesced aggregates can stabilize the bubbles and hold the aqueous phase of ice creams, preventing the outflow during meltdown. Oleogels that form crystal networks can be employed as a preferable replacement for HPKO in the production of ice cream with superior texture.

Investigating Structural Defects in Extra Hard Cheese Produced from Low-Temperature Centrifugation of Milk.

The present study investigated some physico-chemical and microbiological traits of 20-month ripened hard cheeses produced from low-temperature high-speed centrifuged raw milk that developed a structural defect consisting of eyes or slits in the paste. Cheeses obtained using the same process and that did not develop the defect were used as controls. The colour, texture, moisture, water activity, proton molecular mobility, microstructure, extent of proteolysis, and viable microorganisms have been evaluated in all the cheese samples, and the significant differences between the defective and non-defective cheeses have been critically discussed. At a microstructural level, the defects caused fat coalescence and an unevenly organised protein matrix with small cracks in the proximity of the openings. The different fat organisation was correlated to a different transverse relaxation time of 1H population relaxing at higher times. The textural and colour features were not different from those of the control cheeses and were comparable with those reported in the literature for other long-ripened hard cheeses. On the other hand, the defective cheeses showed a higher moisture level and lower lactobacilli and total mesophilic bacteria concentrations, but the microbial origin of the defect remains an open hypothesis that deserves further investigation.

Proteolytic treatment of waste dairy ice cream to accelerate milk fat separation

Waste products are generated within the ice cream manufacturing process for a variety of reasons. Milk fat may potentially be recovered as a valuable ingredient to be reapplied in the human food chain. In this study, Flavourzyme and Formea CTL (chymotrypsin-like protease) were selected and tested on a variety of melted ice creams to destabilize the emulsion and facilitate fat separation. With 1% (w/w) enzyme/protein dose and 1 h reaction at 50 °C, 20–60% of the original emulsion weight was segregated as serum under mild centrifugation. Faster creaming velocity, larger migrating particle size, and decreased continuous phase viscosity were found to contribute to the accelerated separation. Flavourzyme promoted fat flocculation by coagulating milk proteins adsorbed at the fat surface, and chymotrypsin encouraged fat coalescence by removal of the adsorbed proteins from the fat surface. This study provides an efficient first step to recover milk fat from waste ice creams.

Effect of Ultrafiltered Milk on the Rheological and Microstructure Properties of Cream Cheese Acid Gels

The addition of ultrafiltered (UF) milk retentate is known to impact milk properties during mozzarella and cheddar cheese production, but the effect during cream cheese production is less well understood. Little is known about the impact of UF retentate on the intermediate stages of manufacture, such as protein assembly and the formation of hydrated acid gel structures. Here, milk prepared for cream cheese manufacture using a concentration factor of 2.5 or 5 had a similar particle size distribution to unconcentrated cheese milk after homogenization but increased viscosity and a slower rate of acidification, which could be altered by increasing starter culture concentration. The acid gels formed contained more protein and fat, resulting in a higher storage modulus, firmness, and viscosity. A denser microstructure was observed in acid gels formed with UF retentate addition, and quantitative two- or three-dimensional analysis of confocal images found a greater volume percentage of protein and fat, decreased porosity, and increased coalescence of fat. The mobility of water, as assessed by proton nuclear magnetic resonance, was reduced in the dense UF gel networks. Water movement was partially obstructed, although diffusion was possible between interconnected serum pores. These insights improve our understanding of acid gel formation. They can be used by manufacturers to further optimize the early and intermediate stages of cream cheese production when using concentrated milk to reduce acid whey production and lay the foundation for larger pilot scale studies of intermediate and final cream cheese structure.

Insights into the Multiscale Lubrication Mechanism of Edible Phase Change Materials.

Investigation of a lubrication behavior of phase change materials (PCM) can be challenging in applications involving relative motion, e.g., sport (ice skating), food (chocolates), energy (thermal storage), apparel (textiles with PCM), etc. In oral tribology, a phase change often occurs in a sequence of dynamic interactions between the ingested PCM and oral surfaces from a licking stage to a saliva-mixed stage at contact scales spanning micro- (cellular), meso- (papillae), and macroscales. Often the lubrication performance and correlations across length scales and different stages remain poorly understood due to the lack of testing setups mimicking real human tissues. Herein, we bring new insights into lubrication mechanisms of PCM using dark chocolate as an exemplar at a single-papilla (meso)-scale and a full-tongue (macro) scale covering the solid, molten, and saliva-mixed states, uniting highly sophisticated biomimetic oral surfaces with in situ tribomicroscopy for the first time. Unprecedented results from this study supported by transcending lubrication theories reveal how the tribological mechanism in licking shifted from solid fat-dominated lubrication (saliva-poor regime) to aqueous lubrication (saliva-dominant regime), the latter resulted in increasing the coefficient of friction by at least threefold. At the mesoscale, the governing mechanisms were bridging of cocoa butter in between confined cocoa particles and fat coalescence of emulsion droplets for the molten and saliva-mixed states, respectively. At the macroscale, a distinctive hydrodynamic viscous film formed at the interface governing the speed-dependent lubrication behavior indicates the striking importance of multiscale analyses. New tribological insights across different stages and scales of phase transition from this study will inspire rational design of the next generation of PCM and solid particle-containing materials.

Structural, rheological and functional properties of extruded mozzarella cheese influenced by the properties of the renneted casein gels

Renneted casein gels, often named cheese curds, are traditionally pre-heated by immersion in water before stretching, which influences cheese functional properties. This work aims to understand the effect of pre-heating (cooking) on extrusion process of cheese curds at 80 and 90 °C in a lab twin-screw, co-rotating extruder, and consequences for composition, microstructure and functional properties of the extrudates. The cooking significantly enhanced curd meltability and oiling-off, resulting in faster extrusion, higher exit temperature and lower specific mechanical energy. Microscopic observations at different length scales, combining confocal laser scanning microscopy and X-ray micro-tomography, showed that cooking caused extensive fat coalescence and cracks in protein matrix, resulting in extrudates with less fibrous structure, lower elasticity and tensile strength. The extrusion process induced significantly increased of calcium bridges in extrudates, which may replace weak water-protein interactions and increase relaxation time of the more mobile water fraction (T2.2). The specific mechanical energy was less influenced by the extrusion temperature in cooked than uncooked curds, likely due to a more extensive oiling-off during extrusion of the cooked curd. In agreement with the microscopic observations, extrudates obtained at 80 °C differ from 90 °C specially regarding fat content respectively 23.8–24.8% and 29.5% (w/w) and fat globule size and distribution, influencing fiber formation. In general curds extruded at 90 °C had higher elasticity and tensile strength, which was related to the well-elongated fat domains. This study provided knowledge about extrusion process of curds generating new ideas to improve cheese processing and design customized cheese products.

Effects of Glucose and Corn Syrup on the Physical Characteristics and Whipping Properties of Vegetable-Fat Based Whipped Creams.

The aim of this work is to evaluate the effects of glucose and corn syrup on the physical characteristics and whipping properties of whipped creams. The interfacial protein concentration and apparent viscosity of emulsions increased with an increasing sugar concentration. In whipped creams, a shorter optimum whipping time (top), higher fat coalescence degree, higher firmness and higher stability were detected as sugar concentration increased. The partial coalescence degree, overrun and firmness of whipped cream with 30 wt% glucose reached 76.49%, 306% and 3.82 N, respectively, significantly (p < 0.05) higher than those (67.15%, 235% and 3.19 N) with 30 wt% corn syrup. Compared with glucose at the same sugar concentration, higher interfacial protein concentration and less-shaped aggregates and coalescences were observed for the emulsions upon the addition of corn syrup, which caused a lower degree of fat coalescence and a lower firmness of whipped cream. The differences could be explained by the presence of maltodextrin (MDX) in corn syrup, which protects absorbed protein throughout freezing and retards the formation of a continuous network during whipping. As a result, the addition of sugars could well improve stability of emulsion, firmness and foam stability of whipped cream efficiently. With a 25–30 wt% sugar addition, even if there was a lower partial coalescence degree and firmness compared with glucose, whipped cream with corn syrup exhibited relatively good stability. These results suggest that MDX improves the stability of emulsion and, thus, has a potential use in low-sugar whipped cream.

Ultrasound homogenization of milk cream at low temperature

Ultrasonication has been identified as a particularly promising technology for homogenization of dairy products. Homogenization of cream, by reducing fat globule size, can be utilized to inhibit creaming. The homogenization of cream usually leads to increased viscosity. Cream with fat level greater than 17% cannot be homogenized with satisfactory results since conventional homogenization methods cause coalescence and mostly agglomeration. The aim of this study was to investigate the influence of ultrasonication on milk cream (5-30% fat) and to study the phenomenon of formation of fat clusters during sonication (0.5-15 mins) at low temperature (2°C). The results showed that ultrasonication can reduce the fat globule size, although it resulted in the formation of fat clusters at short time (&lt;1min), but at longer time, fat clusters can be broken. On the other hand, ultrasound homogenization tends to increase the viscosity of cream at various fat contents. Microstructure of solid phase showed that there was formation of double emulsions and partial fat coalescence. Ultrasound homogenization with the addition of SDS as small-molecule surfactant can prevent the formation of fat clusters. Fatty acid composition in solid phase shows that it consists of long-chain fatty acids in higher amount compared to that present in the liquid fraction. Whereas the concentration of short and medium chain fatty acids in the liquid phase was higher compared to that in solid phase. The utilization and optimization of ultrasound for cream homogenization has a potency to solve the limitation of conventional method (pressure homogenizer) which commonly used in dairy industry.

Investigating phytosterol as a potential functional component in milk through textural, flavour and oral perception study

Phytosterols (PS) are functional ingredients capable of providing health benefits. This study investigated the potential of incorporating different levels of PS ester (0.8, 1.2, 1.6 and 2.0 g/100 g) into skim milk (0.1 g/100 mL milk fat) to replace the milk fat. PS-enriched milk were analysed for its physical characteristics (colour, viscosity, tribology, particle size and microstructure) and compared to commercial milk (0.1, 1.3, 2 g/100 mL fat, and 1.3 g/100 mL fat with 0.3 g/100 mL PS). Furthermore, the flavour profiles and sensory acceptability of the PS-enriched milk were evaluated. All samples exhibited a characteristic shear-thinning flow behaviour, with 2 g/100 g PS ester milk displaying the highest viscosity (4.46 ± 1.93 mPa s) at 50/s shear rate and 35 °C. Confocal images and particle size distribution suggest fat coalescence resulting in larger fat globules (0.53 ± 0.14 μm) in 2 g/100 g PS ester milk. In general, the addition of PS ester increased the fatty acid and aldehyde compounds of PS-enriched milk, providing comparable lubrication properties and whiteness to commercial milk with the same fat levels. Sensory evaluation revealed that the PS-enriched milk did not possess any off-flavour and milk with 1.6 g/100 g PS ester were the most preferred.

Effect of sucrose ester S370 on interfacial layers and fat crystals network of whipped cream

The effect of sucrose ester S370 on the interfacial layers and fat crystals network of whipped cream has been studied in this work. The addition of S370 showed a little effect on the droplets size, interfacial protein concentration and viscosity of emulsion samples before whipping. However, the addition of S370, as a heterogeneous nucleating agent, could induce nucleation and lead to the formation of more small crystals in the bulk mixture and emulsions. These small crystals, which were not able to pierce the interface of fat droplets effectively, would retard fat coalescence during whipping process. The addition of S370 resulted in lower degree of fat coalescence, lower interfacial protein concentration, shorter optimum whipping time (top) and lower overrun of whipped cream. At lower S370 concentration (<0.05 wt%), large-size crystals and inhomogeneous fat crystals network led to lower firmness and less bubbles stability of whipped cream samples. At 0.05 wt% S370 concentration, homogeneous crystals network, resulted in whipped cream with high firmness and bubbles stability. However, lower interfacial protein concentration and small-size crystals were observed at higher concentration of S370 (>0.05 wt%). As a result, the aerated structure was not strong enough to stabilize whipped cream.

The stability of aerated emulsions: Effects of emulsifier synergy on partial coalescence and crystallization of milk fat

This study investigated the effects of emulsifiers (mono- and diglycerides, Tween 80, LACTEM, and sodium stearyl lactylate), both individually and in combinations, on the partial coalescence of fat globules and fat crystallization behavior, as well as their influence on the stability of aerated emulsions (36 wt% fat). The extent of partial coalescence, solid fat content (SFC), and melting/crystallization profile of bulk anhydrous milk fat (AMF) blends were examined. Furthermore, the interfacial tension, particle size distribution, apparent viscosity, and creaming rate of the quiescent emulsions were measured, while the aeration properties, rheology, and microstructure of aerated emulsions were analyzed. Lipophilic-emulsifier formulas accelerated fat crystallization and achieved higher foam firmness, whereas mono- and diglycerides had a significant positive effect on the crystallization behavior of bulk AMF blends compared to the minor impact on emulsification. Moreover, the highly viscous emulsions that were obtained by combining more hydrophilic emulsifiers could be attributed to more partial coalescence and smaller globule particle size, especially with the inclusion of Tween 80, which was very efficient at reducing interfacial tension. The four-blend emulsifier formula produced a lower emulsion creaming rate and higher aeration activity (overrun) and its foam displayed regularly-shaped air bubbles enveloped by a fat network consisting of well-distributed fat clusters. Overall, the results showed that the choice of emulsifiers played a crucial role in the physical stability of aerated emulsions. • Lipophilic-emulsifier formulas achieved higher foam firmness. • Mono- and diglycerides (MDG) had a positive effect on the fat crystallization compared to the minor impact on emulsification. • Combining more hydrophilic emulsifiers like Tween 80 promoted partial coalescence. • The four-blend emulsifier formula had lower emulsion creaming rate and higher overrun. • The different emulsifier formulas affected the texture of the final aerated emulsion in different ways.

Effects of soy protein composition in recombined soy-based cream on the stability and physical properties of whipping cream.

Recombinant plant-based whipping cream (RSWC) has been widely studied in recent years. The present study investigated the effects of soybean protein and its hydrolysates on the stability and physical properties of the RSWC. The RSWC was made with 28% soybean oil bodies and 4% additional soy proteins or its hydrolysates. The proteins used were soy protein isolate, 7S, 11S, oil body protein, soybean proteins isolate hydrolyzed by pepsin (SPHPe) and soybean protein isolate hydrolyzed by papain (SPHPa). RSWC made with SPHPa containing a large amount of small-molecule polypeptide had the lowest apparent viscosity, shortest whipping time, best overrun and worst whipping stability, whereas RSWC made with SPHPe containing the α, β subunit and small-molecule polypeptides exhibited the second highest overrun and best whipping stability. The partial coalescence of fat and confocal micrographs of cream emulsions suggested that oil body protein was displaced by the small peptides from the interface, which led to partial destabilization and sufficient coalescence of fat globules after aging and whipping. Selectively hydrolyzed soy protein, such as SPHPe, can be used for the production of RSWC with sufficient overrun and whipping stability. This research is of great significance and opens a route to production of the recombinant plant-based cream in the future. © 2020 Society of Chemical Industry.

The Effect of Salt on the Structure of Individual Fat Globules and the Microstructure of Dry Salted Cheddar Cheese

Salting is an essential step in the production of Cheddar and other cheese varieties and is a well-studied process but the effect of salt addition on the microstructure of the milk ingredients and resulting cheese is not well known. This study provides insights into how the primary components in milk and the cheese matrix respond to salting. High concentrations of salt (15–25% (w/w) NaCl) disrupted fat globules due to the increased osmotic pressure. This led to fat coalescence, resulting in large fat globules >10 μm in diameter, together with submicron sized fat globules ~ 120–500 nm in diameter. Salt addition also prevented the visualization of the milk fat globule membrane when added at high concentrations (25% (w/w) NaCl) and induced asymmetry in liquid ordered domains at lower concentrations (10% (w/w) NaCl). The microstructure of the surface of the milled curd was compacted by salt, appearing coarse with 5% (w/w) NaCl or more hydrated with a denser protein structure with 2.5% (w/w) NaCl. After pressing, the curd junctions were fine and thin within the unsalted sample but coarse and thick where 5% (w/w) NaCl was added. Such coarse junctions appear to reduce binding between curd particles leading to a less cohesive cheese. Our results show that NaCl can significantly impact on the structure of fat and protein matrix of the curd surface if salt is not evenly distributed during dry salting. High concentrations of salt can also change the microstructure and texture of the cheese, resulting in a more heterogeneous product.

The application of high purity diacylglycerol oil in whipped cream: effect on the emulsion properties and whipping characteristics

ABSTRACTThe objective of this work was to examine the application of high purity diacylglycerol (DAG) oil in whipped cream as a partial substitute of hydrogenated palm kernel oil (HPKO). The DAG-enriched oil, with a purity of 94.50 wt%, was prepared via the enzymatic glycerolysis of palm oil/peanut oil blend and followed by molecular distillation. The substitute levels of 0, 10%, 20%, 30% and 40% (w/w) DAG for HPKO were employed, and the effects of DAG on emulsion properties, whipping characteristics and sensory quality were investigated. The result showed DAG oil promoted partial coalescence of fat globules in emulsion. As 0–20% DAG was involved in the emulsion, the average particle size (d3,2), surface protein concentration (SPC), partial coalescence of fat and overrun increased during whipping. The results of textural characteristics and sensory evaluation showed that 10-30% DAG substitute for HPKO would be successfully applied in whipped cream.

Effect of Meat Type, Animal Fat Type, and Cooking Temperature on Microstructural and Macroscopic Properties of Cooked Sausages

The aim of this study was to simultaneously study the effect of meat type (chicken breast and leg meat), animal fat type (selected pork back fats having a low and high degree of saturation), and cooking temperature (60 and 70 °C) on the microstructural and macroscopic properties (water and fat binding, texture, and pH) of cooked sausages. In sausages prepared with the most saturated pork back fat, the emulsion stability significantly decreased and the greater part of the total expressible fluid was fat, while the reverse was seen for the more unsaturated pork back fat. This was probably related to fat coalescence at the microstructural level. The cooking loss was slightly lower for sausages prepared with the most saturated pork back fat. The fat type clearly affected the hardness of the cooked sausages, irrespective of the type of meat or temperature. Thus, it can be concluded that small differences in fatty acid composition between the different pork back fats proved to have a great effect on the microstructural and macroscopic properties of the cooked sausages, in contrast with the meat type (muscle fiber type) or temperature which only had a moderate effect.

Interfacial competitive adsorption of different amphipathicity emulsifiers and milk protein affect fat crystallization, physical properties, and morphology of frozen aerated emulsion

This study investigated interfacial competitive adsorption of different emulsifiers, including lipophilic [sucrose stearate 370 (S370); mono- and di-acylglycerols (MDG)] and hydrophilic [sucrose stearate 1670 (S1670) and Tween 20 (TW20)] emulsifiers with milk proteins and its influence on fat coalescence behavior in frozen aerated emulsions (10% w/w fat). Lipophilic emulsifiers accelerated fat crystallization, promoting interface heterogeneous nucleation and partial coalescence of fat droplets. In contrast, hydrophilic emulsifiers favored large fat crystal formation with a reduced rate and capacity of fat crystal protrusion. The combination of surfactants (0.5% w/w) with milk proteins (5% w/w) produced concerted effects on the stability of emulsions. The lipophilic surfactant-protein mixture also enabled strong aeration activity (overrun) and a short melting starting time. Moreover, a remarkable array of bee wax-like network was observed in such lipophilic emulsifier-stabilized frozen whipped emulsions with a similar effect seen between S370 and MDG. However, for whipped emulsions produced with hydrophilic emulsifiers, especially with TW20, fewer and irregularly-shaped air bubbles were notable, contrary to the round, slightly arching shape with glossy surface in frozen whipped emulsions with lipophilic emulsifiers. Overall, lipophilic emulsifiers were superior to hydrophilic emulsifiers in producing the well-textured frozen aerated emulsions.

Physical, textural, and rheological properties of whipped cream affected by milk fat globule membrane protein

ABSTRACTThis work aims at improving the textural and whipping properties of whipped cream by the addition of milk fat globule membrane protein. The determination of particle size distribution and average diameter of whipped cream showed that the small particle size was shifted to a larger range after milk fat globule membrane protein was added. The average particle size (d3,2) of whipped cream reached a maximum value of 5.05 µm at 1% milk fat globule membrane protein, while slowly decreased with increasing milk fat globule membrane protein levels from 2% to 5%. In addition, the partial coalescence of fat increased with the increase of milk fat globule membrane protein levels, and the correlation between the whipping time and the overrun of whipped cream was positive. The addition of milk fat globule membrane protein also altered the rheological behaviour of whipped cream, resulting in the increase of modulus G′ and the loss modulus G″. The results also indicated that higher milk fat globule membrane protein level decreased the serum loss of whipped cream while improved its stability. While milk fat globule membrane protein levels had no significant effect on viscosity, its increasing levels effectively improved the hardness, consistency, and viscosity of whipped cream.

Physical and functional properties of whole milk powders prepared from concentrate partially acidified with CO2 at two temperatures

Effects of carbonation of whole milk concentrate on spray dried powder properties were investigated. Concentrate acidification by CO2 addition (2000 ppm) was found to strongly modify the functional properties (solubility, dispersibility) and structural/physical properties (porosity, free fat) of the resulting powders. For concentrates treated at low temperature (where the majority of emulsified fat is in a solid state at 4 °C), colloidal calcium phosphate (CCP) release, casein dissociation and fat coalescence were observed. For warm CO2 treated concentrates (30 °C) only CCP release was observed. The best functional properties (higher solubility and dispersibility) were found for powders produced from the warm treated concentrates, which were possibly due to the high porosity and better fat globule preservation.