Recent Advances in Lipid Crystallization in the Food Industry.

This review discusses fundamental concepts of fat crystallization and how various processing conditions such as crystallization temperature, cooling rate, and shear or agitation affect this process. Traditional methods used to process fats, such as the use of scraped surface heat exchangers, fractionation, and interesterification, are described. Parameters that affect fat crystallization in these systems, such as shear, crystallization temperature, type of fat, and type of process, are discussed. In addition, the use of minor components to induce or delay fat crystallization based on their chemical composition is presented. The use of novel technologies, such as high-intensity ultrasound, oleogelation, and high-pressure crystallization is also reviewed. In these cases, acoustic and high-pressure process parameters, the various types of oleogels, and the use of oleogelators of differing chemical compositions are discussed. The combination of all these techniques and future trends is also presented.

Probing the mechanisms of enhanced crystallisation of APS in the presence of ultrasound.

Understanding the origins of the enhancement of crystallisation of a lipid (all-purpose shortening, APS) through the application of ultrasound is a fundamental pre-requisite for the exploitation of this technique in a wider context. To this end, we show here a number of measurements designed to probe the mechanisms responsible for this effect. For example, we show how the type of bubble cluster, produced at the sound source, alters the bubble population and residency time. In addition, to probe the various contributions to the enhanced crystallisation rate, isolation of the cluster environment below the piston like emitter (PLE) used as the ultrasonic source was shown to reduce the enhancement observed, but did not remove it entirely. This implied that the exposure of the liquid to pressure shocks and the environment around the cluster has a positive effect on the crystallisation kinetics. In turn the addition of extra seed crystals and mechanical agitation also enhances the rate of crystallisation. Finally, the time at which ultrasonic irradiation of the fluid is applied is shown to alter the kinetics observed. These observations suggest that two components are important: large bubble populations and mechanical effects on pre-existing crystals. These findings suggest that maximising these effects could be an eloquent way to enhance and control the material characteristics of materials produced in this manner.

Protein-based hydrogelled emulsions and their application as fat replacers in meat products: A review.

Recent consumers' concerns about diet and its health benefits has triggered a reduction in consumption of foods rich in sugar, fat, salt, and chemical additives. As a result, an expanded market for functional foods has arisen. In particular, high-fat foods normally composed by saturated fatty acids, cholesterol and trans-fatty acids have been reformulated to be healthier. The primary source of saturated fat ingested by humans includes meats and their by-products that have animal fat as lipid source. The reformulation of these products therefore represents an important strategy to make them healthier for human consumption. Substituting solid fat by unsaturated oils usually affects the texture of the products, and therefore, new structuring methods must be developed to provide vegetable oils a similar characteristic to solid fats and improve their functional and health-related properties. Among these structural models, gelled emulsions (GE) show great potential to be used as healthier lipid ingredients in low-calorie and reduced-fat products, including healthier meat products. This review addresses the GE properties to be used as structuring agent, their in vitro bioaccessibility in meat products and effect on technological, sensorial, microstructural and microbiological characteristics.

Development of an optical flow through detector for bubbles, crystals and particles in oils.

The characterisation of bubbles or particles in an oil poses some unique challenges. In contrast to water solutions, the use of electrochemical detection approaches is more difficult in an oil. However, optical sensing systems have considerable potential in this area. Here we use a flow through channel approach and monitor the light propagation through this structure in an optical transmission sensor arrangement (OTS). This simple approach is demonstrated to be useful at detecting bubbles produced in the oil as a result of cavitation induced by high intensity ultrasound (HIU). The optical technique is shown to have an analytical basis. Bubble detection from an operating HIU source is shown to depend on position of the sensor with respect to the source. Critically, the bubble population can be followed for extended time periods after the ultrasonic source has been terminated. The detection of crystals is also demonstrated. Hence, this technique is ideal for the study of the effects of HIU on oils as they crystallise over extended time periods.

Crystallization Behavior and Quality of Frozen Meat.

Preservation of meat through freezing entails the use of low temperatures to extend a product's shelf-life, mainly by reducing the rate of microbial spoilage and deterioration reactions. Characteristics of meat that are important to be preserve include tenderness, water holding capacity, color, and flavor. In general, freezing improves meat tenderness, but negatively impacts other quality attributes. The extent to which these attributes are affected depends on the ice crystalline size and distribution, which itself is governed by freezing rate and storage temperature and duration. Although novel technology has made it possible to mitigate the negative effects of freezing, the complex nature of muscle tissue makes it difficult to accurately and consistently predict outcome of meat quality following freezing. This review provides an overview of the current understanding of energy and heat transfer during freezing and its effect on meat quality. Furthermore, the review provides an overview of the current novel technologies utilized to improve the freezing process.

Enhanced crystallisation kinetics of edible lipids through the action of a bifurcated streamer.

The processing of healthy foods remains a challenge and any technology with the ability to tailor the physical properties of new materials is in demand. High-intensity ultrasound (HIU) has been identified as a useful processing technique for such activities particularly for edible lipids. HIU has been known to alter the crystallisation kinetics and in turn the resultant physicochemical properties for specific food applications. The role of cavitation dynamics during treatment of oils with HIU is of interest, with the knowledge gained allowing for insight into the complex and still undefined mechanism of action. To this end, the crystallisation kinetics of an edible lipid were investigated in the presence of several distinctly different cavitation conditions. Several cavitation clusters, including a bifurcated streamer (BiS), located on the surface of a piston-like emitter (PLE) were studied, each generated by a specific ultrasonic power level. Only samples crystallised at a low supercooling (ΔTSC) value display significant differences in induction time for each of the selected HIU powers, at least 5 minutes earlier than without exposure to HIU. Substantially better energy efficiencies were seen for the BiS regime (ΔTSC = 5 °C) which coincided with maximal crystal growth rates. An increase in melting enthalpy and elastic modulus is reported in the presence of HIU for all crystallisation temperatures, this effect is larger overall with increasing ultrasonic power. In addition, sonicated samples in the presence of the BiS event were composed of fewer smaller crystals compared to higher HIU powers after 60 minutes at 30 °C. Bubble dynamics recorded during a 10 s sonication period exhibited a greater acoustic attenuation effect for the highest ultrasonic power (75 W). The results suggest that the dynamics of the cluster and the presence of the BiS event are important in terms of energy efficiency and the physical properties of the crystallised lipid material.

Influence of sonication, temperature, and agitation, on the physical properties of a palm-based fat crystallized in a continuous system.

High-intensity ultrasound (HIU) has been used in the past to change fat crystallization and physical properties of fat crystalline networks. The objective of this work was to evaluate how HIU placed on different positions in a scraped surface heat exchanger (SSHE) using different processing conditions affect the physical properties of an interesterified palm olein. The sample was crystallized at two temperatures (20 °C and 25 °C) and two agitation rates (344/208 rpm and 185/71 rpm, barrels/pin worker). HIU (12.7 mm-diameter tip, 50% amplitude, 5 s pulses) was placed at three different positions within the SSHE. After processing, samples were stored at 25 °C for 48 h and analyzed according to the crystal morphology, solid fat content (SFC), oil binding capacity (OBC), melting behavior, viscoelasticity, and hardness. Physical properties were affected by crystallization conditions, by sonication, and by HIU position. The greatest improvement obtained was at 20 °C using low agitation when HIU was placed at the beginning of the SSHE. These conditions result in a sample with 98.9% of OBC, 274 kPa of viscoelasticity and 31 N of hardness. These results show that HIU can be used as an additional processing tool to improve physical properties of a palm-based fat and that the best improvement was obtained as a combination of crystallization conditions and HIU position.

Elucidating mechanisms involved in flavor generation of dry-aged beef loins using metabolomics approach.

The present study was conducted to identify flavor-related chemical compounds and to elucidate beef flavor development in response to dry-aging. Paired grass-fed beef loins (n = 18) were obtained at 7 d postmortem, cut into two sections and assigned to 3 aging methods: conventional dry-aging (DA), vacuum packaged wet-aging (WA) and dry-aging in a bag (DW) for 28 days. Following aging, samples were analyzed for UPLC-MS metabolomics, volatile, fatty acid profiling, and consumer sensory comment analysis. Greater number of proteins and nucleotides derived metabolites were liberated in dry-aged samples compared to WA (P < 0.05). In particular, the liberation of gammaglutmayl peptides and glutamine metabolites through the glutathione metabolism were identified. While fatty acid profile was not affected by treatments (P > 0.05), higher concentrations of volatile compounds were found in the dry-aged (P < 0.05). Dry-aging process decreased the presence of terpenoid and steroid lipid group, which could possibly result in reducing undesirable flavor of grass-fed beef.

Phenolic compounds as antioxidants to improve oxidative stability of menhaden oil-based structured lipid as butterfat analog.

Phenolic compounds, including propyl gallate, 1-o-galloylglycerol, ferulic, gallic, caffeic, rosmarinic, and carnosic acids, tocopherols, and butylated hydroxytoluene (BHT), were investigated as antioxidants to improve the oxidative stability of a structured lipid (SL) produced by the enzymatic acidolysis of menhaden oil with caprylic and stearic acids. SL had similar physical properties to butterfat but was more susceptible to oxidation. The above phenolic compounds were each added to SL as antioxidants. SL with 1-o-galloylglycerol, rosmarinic acid, or BHT showed the highest oxidative stability during an accelerated oxidation test with the total oxidation (TOTOX) value around 250 after 18 days. Oxidation induction time (OIT) using differential scanning calorimetry showed a good correlation with the accelerated oxidation test. A mixture of 1-o-galloylglycerol and tocopherols at 50:50 ppm had the strongest protective effect on SL (OIT = 115.1 min) compared to the other tested compounds or combinations at the same concentration (OIT < 100 min).

Functional properties of dairy phospholipid gels.

In this study dairy phospholipid (PL) gels were made using 3 different concentrations of PL (15%, 30%, and 45%) and soybean oil to determine the gel-forming ability and functional traits that dairy PL have. After 24 h of storage the visual stability, crystal morphology, solid fat content, melting behavior, viscosity, and oil binding capacity of the gels were evaluated. All samples showed visual stability, whereas polarized light microscopy showed that high concentrations of PL reduced PL mobility, preventing tubular micelles from forming at high concentrations of PL (45%). Solid fat content increased with an increase in PL concentration. The melting enthalpy increased as the concentration of PL increased. The viscosity was assessed at 0.01, 0.1, and 1.0 1/s shear rates. A significant difference was observed between the 45% PL samples and the other samples at low and intermediate shear, but at high shear levels, a significant difference was only seen between the 15% PL sample and the other samples. The oil binding capacity showed a significant difference between the 45% PL sample and the other 2 samples. This study shows that dairy PL can be added to a vegetable oil to produce semi-solid material with appropriate functional properties.

Effect of processing conditions as high-intensity ultrasound, agitation, and cooling temperature on the physical properties of a low saturated fat.

The objective of this work was to evaluate the effect that agitation rate, crystallization temperature, and sonication have on the physical properties of a soybean-based fat with low levels of saturated fatty acids crystallized in a scraped surface heat exchanger (SSHE). The sample was crystallized at two temperatures (20 and 25 °C) and agitation rates (344/208 rpm in the barrels/pin worker-high agitation HA and 185/71 rpm barrels/pin worker-low agitation LA), and a constant flow of 11 L/hr. High-intensity ultrasound (HIU - 12.7 mm-diameter tip, 50% amplitude, 5 s pulses) was coupled to a water jacketed flow-cell and placed at three different positions within the SSHE. The combination of all those parameters affected samples' physical properties. Higher oil binding capacity (OBC) and elasticity (G') were obtained at 20 °C compared to 25 °C (77% vs. 63.78% for OBC and 30.4 kPa vs. 6 kPa for G', respectively) due to the smaller crystals formed at 20 °C. Fewer or no differences were observed due to agitation alone, but LA conditions allowed for more secondary nucleation to form due to sonication and resulted in a higher improvement on the properties of the fat. PRACTICAL APPLICATION: Fat crystallization in a scrapped surface heat exchanger (SSHE) combined with a high-intensity ultrasound (HIU) gives a realistic idea of how the HIU would work in an industrial line under continuous flow, shaved shear, and different supercooling. Results from this research will provide industry with tools on how and where to incorporate HIU in their processing line. Moreover, will give information on how to combined crystallization conditions and sonocrystallization in order to obtain improved physical properties.

Effect of storage time on physical properties of sonocrystallized all-purpose shortening.

The purpose of this study was to determine the effect of high-intensity ultrasound (HIU) on the physical properties of an all-purpose shortening and to evaluate how these properties changed during storage (48 hr; 4, 12, and 24 weeks) at 5 °C and 25 °C. Samples were crystallized at 30 °C for 60 min with and without the application of HIU (20 kHz; 3.2 mm-diameter tip, 168 µm amplitude, 10 s). After crystallization, physical properties, such as hardness, elasticity, melting behavior, and solid fat content (SFC), were measured. These properties were also measured during storage. The effect of HIU was significant in changing the SFC, hardness, G' and G'', melting enthalpy, and microstructure of the samples. After 60 min of crystallization, the sonicated samples had higher values of SFC, hardness, elasticity, and melting enthalpy than the ones obtained without sonication (P < 0.05). Changes in these physical properties were associated with the microstructure of the samples since sonication generated smaller, more uniformly sized crystals as well as increased the number of crystals. No differences were observed in the G' of the sonicated samples stored at 25 °C as a function of storage period. The G' of the nonsonicated samples increased until 12 weeks of storage and was maintained up to 24 weeks, suggesting that sonication speed up the formation of a stable crystalline network. Samples stored at 5 °C showed higher value in hardness, G' and G'', and SFC than the ones stored at 25 °C. PRACTICAL APPLICATION: High-intensity ultrasound (HIU) has been widely used as an additional tool to change the crystallization behavior in various lipids; however, the long-term storage effect of HIU has not been studied before. This research evaluates the effect of HIU on the physical properties of a palm-based shortening stored up to 24 weeks at two different temperatures (25 and 5 °C). The application of HIU may help increase the stability of lipid during storage.

Tailoring physical properties of monoglycerides oleogels using high-intensity ultrasound.

The effects of high-intensity ultrasound application (HIU-20 kHz, 96 W, 3 pulses: 10 s on/5s off) and cooling rate (0.1 and 10 °C/min) on physical properties of monoglycerides (MG) oleogels (3, 4.5, and 6 wt%) were evaluated. Oleogels melting profile, rheological and textural properties, crystal microstructure, crystal length (Lc), polymorphic behavior, oil binding capacity (OBC), and solid fat content (SFC) were determined after 24 h of storage at 5 or 25 °C. HIU caused significant changes in the MG crystallization behavior, producing a decrease in Lc and a stronger and more elastic network with higher OBC. HIU increased the adhesiveness of all samples whereas did not affect their cohesiveness. The effects of HIU application were enhanced by cooling at 0.1 °C/min and storing at 5 °C. Neither SFC nor thermal behavior were affected by HIU and the desired ß' polymorphism was obtained in all oleogels. This study shows that physical properties of MG oleogels can be significantly improved by HIU application to obtain suitable fats with low level of saturated fatty acids for food applications.

Sonocrystallization as a tool to reduce oil migration by changing physical properties of a palm kernel fat.

Oil migration (OM) has been an immense issue in fat-based foods such as peanut butter and chocolate fillings. The objective of this study was to evaluate the effect of high-intensity ultrasound (HIU) on OM in a palm kernel oil-based fat used in chocolate fillings, coatings, and confectionery applications. The sample was crystallized at 30 °C for 90 min and stored for 48 hr at 25 °C. HIU was applied after 20 min at 30 °C using a 3.2-mm diameter tip operating at an amplitude of 216 µm (90 W) for 10 s. OM was measured using a centrifuge- and a filter paper-based method. Crystal morphology and size, solid fat content (SFC), melting behavior, and hardness were evaluated after 90 min, 48 hr, and after OM. Results showed that HIU reduced OM (P < 0.05) by 52.0% when measured using the filter paper method while a reduction of 97.4% was observed when measured with the centrifuge method. HIU also reduced the crystal size (P < 0.05) and formed a more organized crystalline network. A reduction in peak temperature (Tp ) after 90 min of crystallization and 48 hr of storage was observed in sonicated samples without affecting the enthalpy. However, enthalpy and Tp were higher in the sample without HIU analyzed after OM due to the migration of low melting point triacylglycerols out of the crystalline network. HIU also increased the hardness (P < 0.05) from 1.37 N and 3.17 N. But no differences (P > 0.05) were found on SFC due to sonication. Overall, HIU changed the crystalline structure of the fat allowing for a better entrapment of liquid oil in the crystalline matrix. Results from this study will benefit food producers that are looking for fat sources with better capacity to entrap oil. PRACTICAL APPLICATION: OM is one of the main problems facing the fat industry, especially since the elimination of partially hydrogenated fats from foods. Efforts are being focused on finding new technologies to reduce OM and therefore to improve the shelf life of the product. This study introduces for the first time, a new processing technology to reduce OM in a palm kernel fat with high content of saturated fatty acids that is commonly used in confectionery applications.

Interlaboratory Measurement of Rheological Properties of Tomato Salad Dressing.

Rheological properties of food materials are important as they influence food texture, processing properties, and stability. Rotational rheometry has been widely used for measuring rheological properties. However, the measurements obtained using different geometries and rheometers are generally not compared for precision and accuracy, so it is difficult to compare data across different studies. In this study, nine rheometers from seven laboratories were used to measure the viscosity and viscoelastic properties of a commercial salad dressing. The measurements were obtained at three temperatures (8, 25, and 60 °C) using different diameter parallel plates (20, 40, 50, and 60 mm). Generally, the viscosity measurements among rheometers differed significantly ( P < 0.05 ). For larger geometry diameter (40, 50, and 60 mm) and at lower temperatures (8 °C), viscosity measurements at lower shear rate (0.01, 0.1, and 1.0 s-1 ) were significantly different. Rheometer brand significantly affected storage modulus only at low (0.01%) and high levels (10% and 100%) of strain. Temperature was an influencing factor on viscoelastic behaviors only at high strain (>10%). Storage moduli values obtained by frequency sweeps were not affected by rheometer or plate diameter. Overall, rheometer, geometry, and temperature can influence rheological measurements and care should be taken when comparing data across laboratories or published works. Higher shear rates (≥10 s-1 ) and moderate strains (0.1% to 10%) generally provide more repeatable data among different laboratories. PRACTICAL APPLICATION: This study provides information on what factors may potentially influence rheological measurements conducted across different laboratories. It is useful for rheometer users who want to compare their experimental data to published data or compare two sets of published data. It is better to compare data collected at shear rates 10 s-1 and strains between 0.1% and 1.0%.

Physical Properties of Monoglycerides Oleogels Modified by Concentration, Cooling Rate, and High-Intensity Ultrasound.

The aim of this study was to investigate the effects of monoglycerides (MG) concentration (3, 4.5, and 6 wt%), cooling rate (0.1 and 10 °C/min), and high-intensity ultrasound (HIU) application on physical properties of oleogels from MG and high oleic sunflower oil. Microstructure, melting profile, elasticity (G'), and solid fat content (SFC) were measured immediately after preparation of samples (t = 0) and after 24 hr of storage at 25 °C. Samples' textural properties (hardness, adhesiveness, and cohesiveness) and oil binding capacity (OBC) were evaluated after 24 hr at 25 °C. In general, samples became less elastic over time. Slow cooling rate resulted in lower G' after 24 hr compared to the ones obtained using 10 °C/min. Network OBC was improved by increasing MG concentration and cooling rate, and by applying HIU. After storage, oleogel melting enthalpy increased with MG concentration. In general, this behavior was not correlated with an increase in SFC. An improvement in the network structure was generally reached with the increase in cooling rate, according to texture and rheology results, for both sonicated and nonsonicated conditions. At the highest MG concentration, HIU application was more efficient at increasing OBC and hardness of the network at 0.1 °C/min. Microscopy images showed that the oleogels microstructure was changed as a consequence of HIU application and cooling rate, evidencing smaller crystals both in sonicated and faster cooled samples. Obtained results demonstrate that cooling rate, MG concentration, and HIU can be used satisfactorily to tailor physical properties of MG oleogels. PRACTICAL APPLICATION: Oleogels have been studied in the last years as semisolid fat replacers in food products. Cooling rate is an important processing parameter in the oleogel preparation because it affects their final physical properties, while high-intensity ultrasound (HIU) is a relatively novel technique to tailor lipid properties. This study is focused on the application of a slow/fast cooling rate in combination with/without HIU treatment at different monoglycerides and high oleic sunflower oil mixtures as a successful strategy to obtain oleogels with different physical properties and with potential applications in the food industry, such as fat substitutes in bakery.

Interactions between candelilla wax and saturated triacylglycerols in oleogels.

Fully hydrogenated oils or hardfats are low cost and highly available products used in lipid technology while candelilla wax (CLX) is a well-known oleogelator that has been thoroughly studied over the last decade. CLX is capable of making a strong oleogel when used in very low concentrations (~1.5%) while hardfats need to be added in higher concentrations (>10%) to form a gel. Based on the molecular similarity between hardfats and CLX the aim of this work is to evaluate the use of CLX and various hardfats in combination to form stable oleogels. The hardfats used in this study in combination with CLX were crambe (HCr), palm (HPl), palm kernel (HPk) and soybean (HSb). The total concentration of oleogelator used was 5% and soybean oil was used as the dispersing media. The proportions of 0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25 and 1:0 of CLX:hardfats were studied. HPl and HCr fats formed a more stable and organized crystal network when used in all blends as shown by a shift towards to lower melting temperatures. However, G' and oil loss were close to CLX only when HPl was added in small amounts (0.25 and 0.5). The HSb fat presented similarity to CLX only for blend 0.25. HPk did not show any interaction with CLX due to the different triacylglycerol composition of this hardfat compared to the others. These results show that hardfats have the potential to be used in oleogel formulation especially when used in combination with CLX. The use of hardfats is attractive to producers since they are inexpensive and readily available and they can be used to reduce the total amount of CLX in food formulations avoiding the common waxy sensation associated with CLX formulations.

Modifying the physical properties of butter using high-intensity ultrasound.

The physical qualities of butter are affected by the physical properties of the cream used to make it. The objective of this study was to evaluate the effect of high-intensity ultrasound (HIU) on the physical properties of cream and butter. High-intensity ultrasound (frequency: 20 kHz, amplitude: 108 µm), often called sonication, was applied for 0, 10, 30, 60, and 90 s using a 1.27-cm-diameter tip to heavy cream (40% fat; 300 g) that was aged at 7.5°C with low agitation (40 rpm) for 90 min. Sonicated cream was churned at 7.5°C until butter grains were formed. The solid fat content (SFC), melting behavior, and average fat droplet size of cream were measured after HIU treatment. Butter was characterized by SFC and melting behavior immediately after production and was tested for SFC, melting behavior, and hardness after storage for 24 h at 5°C. High-intensity ultrasound did not affect the average fat droplet size of cream. Sonicating cream for 30, 60, and 90 s slightly decreased SFC due to the temperature increase (2-6°C) that occurred during HIU application. Two melting peaks were observed at approximately 17 and 33°C in all the cream samples. A significantly lower peak temperature was observed in cream sonicated for 10 s compared with creams sonicated for 30 and 60 s. A relatively shorter churning time of sonicated cream compared with nonsonicated cream was observed, possibly because HIU weakens the fat globule membrane. Two melting peaks were observed in all butter samples at approximately 16 and 33°C. Treatment with HIU for 10 to 60 s significantly increased the hardness of butter. When HIU was applied to cream for 10 s, the hardest butter was obtained, with the lowest onset temperatures and highest enthalpy values for both melting peaks. Treatment with HIU for 10 s promoted crystallization of low-melting-point triacylglycerols (TAG) during churning, which resulted in a harder material. Significantly lower enthalpy values for the high-melting-fraction TAG were observed in butters treated with HIU for 60 and 90 s compared with non-HIU-treated butter, which suggests that a longer duration of HIU promotes melting of high-melting-point TAG. The hardness of butter was correlated with the enthalpy values of the low-melting fraction and with total enthalpy values of fresh butter. However, further crystallization occurred in the butter during 24 h of storage at 5°C, and all differences in enthalpy values disappeared. In conclusion, exposure of cream to HIU can be used to modify the physical properties of butter, and the effects of HIU depend on the length of HIU treatment.

Effect of cream aging temperature and agitation on butter properties.

Aging of cream is an important process to manage production time and to produce butter with consistent quality. The objective of this study was to evaluate the combined effect of temperature (5, 10, and 15°C) and agitation rate (0, 40, and 240 rpm) during aging of cream on the physical properties of cream and butter in a model system. Cream's solid fat content (SFC), melting behavior, and droplet size distribution were measured during and after 90 min of aging. Butter physical properties such as melting behavior, water content, and hardness were measured. The effects of agitation on SFC and droplet size are dependent on aging and churning temperature. Solid fat content increased faster at 5°C, and the maximum SFC was the highest at this temperature. An effect of agitation on SFC was observed only when cream was aged at 15°C. Agitating cream at 40 rpm increased the droplet size regardless of aging temperature. Two melting peaks, medium melting fraction (MMF) and high melting fraction (HMF), were found in cream samples aged at 5 and 10°C, but only a HMF melting peak was seen in the cream aged at 15°C. The enthalpy of MMF in the cream aged at 10°C with 40 rpm and without agitation was significantly lower than that in samples aged at 5°C regardless of agitation rate. Butter can be formed only from cream aged under certain conditions during 14.5 min of churning, which are 5°C with high agitation and 10°C regardless of agitation level. Butter produced with cream aged at 5°C with high agitation showed significantly higher MMF and total enthalpy values. However, no significant difference in enthalpy values was observed among the butter samples made from the cream aged at 10°C. Further crystallization of MMF occurred in the butter produced with cream aged at 10°C during 24 h of storage at 5°C, whereas no further crystallization occurred in the butter made with the cream aged at 5°C with high agitation. The hardest butter was obtained when cream was aged at 5°C with 240 rpm and at 10°C with 40 rpm. Softer butter was obtained when cream aged at 10°C with 240 rpm was used. This butter also had the highest water content. This study shows that butter hardness can be tailored by changing the aging conditions of the cream. Cream can be aged at higher temperature with low agitation without altering the hardness of butter. These results will help dairy producers to optimize butter making processes to obtain desired properties in the final product.

Dry-aging improves meat quality attributes of grass-fed beef loins.

The objective of this study was to evaluate the effect of dry-aging on meat quality and microbiological properties of grass-fed beef loins. At 7 d postmortem, eighteen bone-in loins (M. longissimus lumborum) from 9 beef carcasses (USDA Select) were obtained. Each loin was cut in half yielding a total of 36 sections, which were assigned to three aging methods: wet-aging (WA); dry-aging (DA); and dry-aging in a water permeable bag (DW). DA resulted in greater shrink and trim loss compared to WA (P < 0.05). However, DW minimized moisture and trim loss resulting in an increase in total saleable yield up to 4%. DA samples were lowest in both aerobic/anaerobic bacteria (P < 0.05). DA steaks had significantly higher flavor and tenderness preferences compared to WA counterparts. Consumers determined DW to have greater juiciness compared with WA (P < 0.05). Our findings indicate that dry-aging could improve eating quality attributes of low marbled grass-fed beef without adversely affecting microbial characteristics.