Fat Melting Research Articles

Degummed Crude Canola Oil Supplementation Affects Fat Depot Melting Points in Purebred and First-Cross Merino Sheep

The objective of this study was to test the hypothesis that degummed crude canola oil (DCCO) will lower fat melting points (FMP) of both visceral and subcutaneous fats in lambs. Twenty-four lambs comprising purebred and first-cross Merino progeny from Dorset, White Suffolk and Merino sires mated to purebred Merino ewes were supplemented with varying levels of DCCO over a nine-week period. The experimental treatment groups were: Control (1kg plain wheat-based pellets only), Medium (500g plain wheat-based pellets + 500g wheat-based pellets containing DCCO), and High (1kg wheat-based pellets containing DCCO at a concentration of 50ml/kg) supplementation levels. The flock comprised eight wether and ewe lambs per treatment. However, at the end of the trial, four Merino ewes were retained in the flock for breeding purposes, while the remaining twenty lambs were slaughtered in a commercial abattoir. Visceral fat samples were taken from the kidney region and subcutaneous fat samples were taken from the Longissimus dorsi muscle. FMP was determined using temperature slip point methodology in the laboratory. DCCO had significant effects on the FMP of both subcutaneous (p 0.0002) and visceral (p<0.0001) fats, with the lowest FMP achieved at high levels of supplementation in both fat depots. Significant sire breed differences (p<0.0001) were also detected in which Dorset-sired progeny had the highest melting points in both fat depots. The results of this study indicate that within fat depots, DCCO supplementation produced softer fats with lower melting points, suggesting potentially healthier fats likely to contain higher levels of unsaturated fatty acids.

Melting and crystallization DSC profiles of milk fat depending on selected factors

The aim of this study was to test selected factors, such as sample preparation and measurement procedure, potentially influencing repeatability of DSC analysis of milk fat melting and crystallization. The study investigated the effect of such factors as scanning rate, type of sample pans, method of butter dehydration, and final temperature in the cooling experiment. Based on recorded results, it was observed that cooling rate has a considerable effect on temperature, enthalpy, and height of peaks in the process of milk fat crystallization, as well as peak height and enthalpy in the melting process. By contrast, in the melting process no significant differences were observed in all measured temperatures in the range of heating rate of 2–20 °C min−1 (p > 0.05). No statistically significant effect on thermodynamic parameters was found for sample pan type, the applied butter dehydration method and various final cooling temperatures (−60, −50, and −40 °C) either in the melting or crystallization processes. Only temperature of the second peak (T c2) in the crystallization process constituted an exception in this respect, with significant differences (p ≤ 0.05) being recorded depending on the applied pan and dehydration method. With regard to the dehydration method, for the extraction and centrifugation methods the first peak forming during crystallization was characterized by high instability, manifested by various peak shape. Generally, it was found that the analysis of the melting and crystallization processes in milk fat, despite its complex composition, is characterized by high repeatability. Mean values of RSD calculated from all the experiments were very low, i.e., 1.8 % for the temperature in the melting process and 1.5 % in crystallization, 0.9 % for melting enthalpy, and 3.2 % for crystallization enthalpy, whereas for peak heights in melting it was 2.9 % and for crystallization it was 9.3 %, respectively.

Influence of the Colloidal Structure of Dairy Gels on Milk Fat Fusion Behavior: Quantification of the Liquid Fat Content by In Situ Quantitative Proton Nuclear Magnetic Resonance Spectroscopy (isq 1H NMR)

Dairy gels (DG), such as yoghurts, contain both solid and liquid fats at the time of consumption, as their temperature rises to anything between 10 and 24°C after being introduced into the mouth at 4°C. The mass ratio between solid and liquid fats, which depends on the temperature, impacts the organoleptic properties of DG. As the ordinary methods for determining this ratio can only be applied to samples consisting mainly in fat materials, a fat extraction step needs to be added into the analytical process when applied to DG, which prevents the study of the potential impact of their colloidal structure on milk fat fusion behavior. In situ quantitative proton nuclear magnetic resonance spectroscopy (isq (1) H NMR) was investigated as a method for direct measurements in DG: at temperatures between 20.0 and 70.0°C, the liquid fat content and the composition of triacylglycerols of the liquid phase (in terms of alkyl chains length) were determined. Spectra of isolated milk fat also enable the quantification of the double bonds of triacylglycerols. Statistical tests showed no significant difference between isolated milk fat and milk fat inside a DG in terms of melting behavior: the fat globule membrane does not seem to have a significant influence on the fat melting behavior.

Thermal Analysis of Lipid Crystallization and Water Ice on Coconut Milk Emulsions: Effect of NaCl Concentrations

The aim of this study was to investigate the effect of NaCl concentrations at low temperature (50 to -80C) on lipid crystallization and freezing water of coconut milk emulsions. Phase change behavior of coconut milk emulsions has been evaluated using differential scanning calorimetry at heating/cooling rate of 2C/min. Unhomogenized coconut milks (34% fat content) showed an overlapping peak of fat crystals with an onset at 8C and a large exothermic peak of freezing water at -20C during cooling. Reheating sample leads to water ice melt at 0C and subsequently a melting of coconut fat with an endset of 25C. Commercial coconut milks (18 – 20% fat content) exhibited more than three peaks of crystallization due to a variety of oil droplet sizes in emulsions. To study the effect of salt, NaCl (0 – 4%) were then added to coconut milk (20% fat content) containing 5%w/w acacia gum. Homogenized coconut milk emulsions showed lower crystallization and melting temperatures of water ice in the presence of NaCl. However, it does not affect phase change of fat crystals. Freezing depression could be seen only on aqueous phase of its emulsion. 

CRYOGENIC GRINDING: A PHYSICAL TECHNIQUE TO RETAIN VOLATILE CONTENT IN NATURAL PRODUCTS

Cryogenics is the study of the production of very low temperature (below −150°C, −238°F or 123K) and the behavior of materials at those temperatures. Similarly, cryogenic grinding is a term supported by the act of grinding a thing at very low temperature. This technique is generally used to grind the material, which contains heat labile constituents viz- volatile oils in seed spices. Due to high fat content in spices, heat is generated, while energy is used to fracture a particle into a smaller size in conventional grinding process. During the normal grinding process, this generated heat causes temperature rise of grinder upto 950C. The increased temperature is responsible for a loss of volatile content in the tune of about 30% and also produces dark colour powder. Generally, continuous operation is not possible in normal grinding process due to melting of fat and sticking of powder on the grinding surface. The loss of volatile content can be significantly reduced by cryogenic grinding technique using liquid nitrogen or liquid carbon dioxide that provides the refrigeration needed to pre-cool the spices and maintain the desired low temperature by absorbing the heat generated during the grinding operation. The extremely low temperature during grinder condenses the volatile matter and retains their presence in spices. The application of cryogenic technology for grinding of spices has been scientifically proved to be a suitable technique with negligible loss of volatile content and improved colour of oil and grinding operation of seeds.

Short communication: Diet-induced variations in milk fatty acid composition have minor effects on the estimated melting point of milk fat in cows, goats, and ewes: Insights from a meta-analysis

In ruminants, the ability to maintain milk fat melting point within physiological values could play a role in the regulation of milk fat secretion when milk fatty acid (FA) composition varies, such as in response to feeding factors. However, the relationship between milk fat fluidity and changes in milk FA composition is difficult to study experimentally. A meta-analysis was therefore conducted to compare the magnitude of diet-induced variations in milk FA composition and the calculated melting point of milk FA (used as a proxy to estimate the variations in the melting point of milk fat) in 3 dairy ruminant species (cow, goat, and sheep). The coefficient of variation (CV), a scale-free measure of statistical dispersion, was used to compare the variability of criteria differing in their order of magnitude. The analysis of a database of milk FA profiles from cows, goats, and sheep fed different dietary treatments (unsupplemented diets and diets supplemented with lipids rich in oleic acid, linoleic acid, linolenic acid, or C20–22 polyunsaturated FA) revealed that the variability of the calculated melting point of milk FA was narrow (CV of 5%) compared with the variability of milk FA percentages (CV of 18 to 72%). The regulation of the melting point of milk fat is thus probably involved in the control of diet-induced variations in milk fat secretion. The calculated melting point of ewe milk FA was approximately 3°C lower than that of goats or cows across all types of diets, which might be linked to differences in milk fat content (higher in sheep) or the structure of milk triacylglycerides among these species. Lipid supplementation increased the calculated melting point of C18 FA in milk, whereas that of total FA was significantly reduced by supplements rich in oleic, linoleic, and linolenic acids but not C20–22 polyunsaturated FA. However, the slight effects of dietary treatments on the calculated melting point of milk FA did not differ between cows, goats, and ewes.

Releasing Fat in Whole Milk Powder during Fluidized Bed Drying

Spray-dried whole milk powders have been produced to a high bulk-to-surface-free-fat ratio due to the susceptibility to oxidation of surface free fat. Processing spray-dried whole milk powders in a fluidized-bed crystallizer by hot and high humidity air can cause the release of bulk fat and increase both inner free and surface free fat. This research investigates the fat release and its migration to particle surfaces by two different mechanisms: a) fat melting due to high temperature processing in a fluidized -bed crystallizer so that liquid fat can diffuse outwards to the particle surfaces; b) fat release from the matrix due to lactose crystallization, causing component segregation and releasing molecular bonds. More free fat is preferable in some dairy-based processing, such as chocolate making, where cocoa butter could be substituted by milk fat to adjust the viscosity of chocolate paste and formulate good chocolate taste. This research shows the possibility of releasing more than 90% of the bulk fat to increase free fat (inner and surface) in 15 minutes processing time. Different temperatures and humidities (45°C and 78% RH) have been found to provide suitable conditions to release the bulk fat by crystallizing lactose in higher amount, as a form of inner free fat (preferentially) which is ready for further use, such as in chocolate industries. Meanwhile the released fat, as inner free fat, has less contact with oxygen than surface free fat and maintains the powder quality better. The changes in particle structure and fat release processes have also been studied during fluidized-bed drying of spray-dried whole milk powders that could improve the control and design of the drying process for milk powders.

Effects of corn DDGS in combination with compound enzymes on growth performance, carcass fat quality, and plasma and tissue redox homeostasis of growing-finishing pigs

The trial was conducted to investigate effects of corn dried distillers grains with soluble (DDGS) and compound enzymes on growth performance, carcass fat quality, and plasma and tissue redox homeostasis in growing-finishing pigs. 200 Pigs (Duroc×Landrace×Yorkshire, about 30kg BW) were randomly allotted to one of four treatment groups (5pens/treatment and 10pigs/pen). The control (T0) was fed a basal corn-soybean meal diet. Treatment 1 (T1), 2 (T2), and 3 (T3) were fed corn-soybean meal-DDGS diets, with 10% corn DDGS in growing phase and 15% in finishing phase, respectively. 0.2g/kg compound enzymes were added to the diets of T2 and T3 and digestible energy (DE) level of T3 was reduced 0.21MJ/kg. The results of growth performance showed that all groups had comparable (P>0.05) results on ADG (682.15g, 671.99g, 709.28g, 700.29g), ADFI (2.00kg, 2.02kg, 2.04kg, 2.10kg) and feed conversion ratio (2.94, 3.01, 2.88, 3.00). Nevertheless, DDGS containing diets significantly increased iodine value (P<0.05) and decreased fat melting point of backfat and belly fat (P<0.05). For backfat and longissimus muscle (LM) intramuscular fat, DDGS containing diets increased unsaturated fatty acids (UFA) content (especially oleic acid and linoleic acid) (P<0.05), while decreased saturated fatty acids (SFA) content (especially palmitic acid and stearic acid) (P<0.05) and SFA:UFA ratio (P<0.05). Furthermore, DDGS containing diets reduced antioxidant activity of plasma and tissue. The activity of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and total antioxidative capacity (T-AOC) of plasma decreased in T1, T2 and T3 compared to T0, while malondialdehyde (MDA) content increased, especially in T3 (P<0.05). DDGS containing diets slightly decreased the activity of GSH-Px, SOD and T-AOC in liver and cardiac muscle (especially T3), while increased MDA content of kidney and spleen significantly (P<0.05). In conclusion, although there were no negative effects on the growth performance of growing-finishing pigs, DDGS containing diets decreased carcass fat quality by increasing iodine value and UFA content in backfat and LM intramuscular fat and decreasing fat melting point and SFA:UFA ratio, and altered the redox homeostasis of plasma and tissue by increasing oxidant (MDA) content and decreasing antioxidant content. Furthermore, adding compound enzymes to DDGS containing diets tended to increase the ADG of growing-finishing pigs.

Optical monitoring of milk fat phase transition within homogenized fresh milk by Photon Density Wave spectroscopy

Photon Density Wave (PDW) spectroscopy was applied for temperature dependent monitoring of melting and crystallization of milk fat within homogenized fresh milk. As an in-line process analytical technique, PDW spectroscopy quantifies continuously the optical properties of turbid material, providing an insight into its structural processes. Here, the measured absorption coefficients reflect temperature as well as fat content of milk and the reduced scattering coefficients probe physical changes of the light scattering fat droplets and casein micelles. Thermal processing reveals breakpoints within the temperature trend of the reduced scattering coefficient of fat containing milk. Found at 16 °C and 24 °C while cooling and heating, respectively, they are associated to the phase transitions of milk fat. Continuous isothermal measurement of the optical coefficients showed that the crystallization process requires several hours. The strongly changing reduced scattering coefficient implies that the thermal history of milk will have a major impact on any method based on light scattering as quantitative analytical technique.

Melting Moments: The Greasy Sources of Modern Perceptions of Fat

In 1822 a rather bizarre satirical piece turned up in Blackwood’s Edinburgh Magazine. Occasioned by the recent challenge that Thomas Malthus had launched against the economic theories of Jean-Baptiste Say, a cheeky yet anonymous writer intervened with a report on a fictitious German economist named ‘Professor Gunthred Bumgroschen’, 1 whose theory of ‘save-all-ism’ represented a unique contribution to the debate. Upon a visit to England, it seems, the good professor had been struck by the size of its inhabitants, who took up more space on the streets than the slender Parisians across the Channel, prompting him to speculate on how the British might make the most economical use of their excess fat. Explaining how Bumgroschen considered the human corpse to be ‘a valuable mass of materials’ that ‘ought not to be suffered to undergo a useless decomposition in a deep grave’, this author proposed ‐ with tongue firmly in cheek ‐ that a reformed Britain would take better advantage of its corpulent dead. Bumgroschen’s plan was to transform the nation’s ‘morbid accumulation’ of fat ‐ which had been ‘a noxious mass to the individual while living’ ‐ into ‘a valuable accumulation for posterity’. This would be accomplished by melting fat corpses to make soap and oil. Hygiene, both personal and moral, would be the two main benefits of Professor Bumgroschen’s unorthodox plan. Those unfortunates who might have otherwise worn flannel or unlaundered clothes would now be able to don white muslin and clean shirts as a matter of course. So rich were British fat supplies that they would provide enough soap ‘to keep the entire world clean’, thus extending the virtues of hygiene beyond the island nation. There would even be enough to render the

Organisation structurale et moléculaire des lipides dans les aliments : impacts possibles sur leur digestion et leur assimilation par l’Homme

From the nutrition point of view, lipids are primarily considered as energy suppliers, their dietary intake having to be limited. In fact, lipids are sources of various fatty acids, and dietary recommendations include the required daily intakes in different fatty acids (fatty acid profile). Beyond these quantitative aspects, fatty acids are part of larger molecules, mainly triacylglycerols (TAG), that are organized in supramolecular structures as for example fat crystals and lipid droplets. Recent advances in nutrition research have demonstrated that these structures, and lipid organization in food matrices, influence digestibility and metabolism of fatty acids. Therefore, the members of the technological network Listral propose a synthesis of the knowledge about the influence of molecular and supramolecular structures of lipids on digestion and metabolic fate of dietary fatty acids originating from for the main food industry sectors. Fatty acids are mainly provided in the diet in the form of TAG, or phospholipids (PL) where they are esterified in external (sn-1, sn-3) or internal (sn-2) position of the glycerol backbone. They can also be found as ethyl esters (EE) in specific formulations. These molecular characteristics of the lipid molecules affect their hydrolysis and their absorption rate but also their metabolism in indifferent organs, as assessed in studies often using inter esterified fat sources. The results depend on the types of fatty acids (saturated or polyunsaturated fatty acids) but also on the model used for the studies: in vitro or in vivo studies; animal model, human newborn or adult, either healthy or exhibiting some diseases. Among others, it was found that the crystal form and fat melting point as affected by the fatty acid profiles and the lipid molecular structures directly impact fatty acid absorption kinetics through modifications of lipolytic enzyme activities. However, in these studies, the relative effect of the thermal properties of lipids and the proportion of saturated fatty acids chains in sn-2 position were hardly distinguished. Supramolecular structures, namely type and size of the fat droplets and their interfacial composition, of lipids, either in their native forms or obtained after food processes, also affect the digestibility and absorption of lipids. This aspect is reviewed with specific focus on dairy, marine, meat, oil plant and egg products. The impact of other nutritional components present in these food matrices on the absorption of lipids is also discussed.

Fine mapping of porcine SSC14 QTL and SCD gene effects on fatty acid composition and melting point of fat in a Duroc purebred population

The stearoyl-CoA desaturase (delta-9-desaturase; SCD) gene is a candidate gene for fatty acid composition. It is located on pig SSC14 in a region where quantitative trait loci (QTL) for fatty acid composition were previously detected in a Duroc purebred population. The objective of the present study was to fine map the QTL, to identify polymorphisms of the pig SCD gene and to examine the effects of SCD polymorphisms on fatty acid composition and melting point of fat in the population. The pigs were examined for fatty acid composition and melting point of inner and outer subcutaneous fat and inter- and intramuscular fat; the number of pigs examined was 479-521. Two SNPs (g.-353C>T and g.-233T>C) were identified in the promoter region of the SCD gene and were completely linked in the pigs from the base generation. In all pigs, 19 microsatellite markers and SCD haplotypes were then genotyped. Different statistical models were applied to evaluate the effects of QTL and the possible causality of the SCD gene variants with respect to the QTL. The results show that all significant QTL for C14:0, C18:0, C18:1 and melting point of fat were detected in the same region, located near the SCD gene. The results also show a significant association between SCD haplotypes and fatty acid composition and fat melting point in this population. These results indicate that the haplotype of the SCD gene has a strong effect on fatty acid composition and melting point of fat.

Triacylglycerol and melting profiles of milk fat from several species

Gas chromatography and differential scanning calorimetry (DSC) were used to differentiate the fats of cow, goat, sheep, water buffalo, donkey, horse and camel milk (n = 20 for each species). Principal component analysis of triacylglycerol (TAG) composition allowed classification into groups according to species; profiles from species of greater genetic similarity were more alike. According to TAG profiles, cow, water buffalo, sheep and goat milk fat were grouped together, as were horse and donkey milk fat, whereas camel milk fat was in a third group. DSC was used to study the melting of milk fat. Similarities were apparent from melting data of cow, water buffalo, sheep and goat milk fat, while clear distinctions could again be made between these milk fats and horse and camel milk fat. Correlating TAG and DSC data highlighted that predominantly the higher molecular weight TAGs (C40 and greater) determined the DSC melting profiles for the various species.

Evaluation of mesotherapeutic injections of three different combinations of lipolytic agents for body contouring

Background: There has been significant interest recently in the technique of mesotherapy as a method of ‘melting fat’ for body contouring. Objective: The aim of this study was to evaluate the safety, efficacy and lipolytic potential of several compounds commonly used in cosmetic mesotherapy. Methods: A total of 75 women (mean age: 33 years) were separated randomly into three mesotherapy groups. Injections were performed for 15 treatments once a week. The main component of each cocktail was phosphatidylcholine/deoxycholic acid for group 1, caffeine for group 2, and Conjonctyl® for group 3. Outcome was evaluated by weight, body fat percentage (BFP), circumference measurements, and patient questionnaires. Results: Seventy-two of all the patients (96%) showed a circumference loss. An average circumference reduction of 4.41 cm per site for group 1, 2.99 cm for group 2, and 2.10 cm for group 3 was achieved. Mean body circumference loss was statistically significant, with p < 0.00. Weight loss was 5.33 ± 1.09 kg for group 1, 3.74 ± 1.51 kg for group 2, and 2.82 ± 1.43 kg for group 3. Seventy-four subjects (98.7%) showed a BFP decrease. A questionnaire indicated high patient satisfaction (63%). No patient showed irregularities, dimples or any serious side effects after treatment. Conclusion: Mesotherapy is a well-tolerated and effective alternative treatment modality for reducing the diameter of body circumference.

Konjac gel fat analogue for use in meat products: Comparison with pork fats

The paper reports a study of the characteristics of konjac gel fat analogue as compared to types of pork fat for use in fat reduction strategies for meat products. Various characteristics—colour, mechanical/rheological behaviour and thermal properties—of pork fats (backfat-PBF and trimmed fat-PTF) and konjac gel (KFG) with different physical structures (intact or ground to 4 and 8 mm) were studied. Pork fat melting processes were evaluated by differential scanning calorimetry (DSC) at above- and below-zero temperature ranges with PBF and PTF always showing similar net results. KFG did not show any thermal event in the range from −40 to 100 °C except the freezing/melting of its constitutional water. While water and fat binding properties of pork fats were affected by fat type and structural disintegration (ranging between 0 and 77%), in all cases KFG presented excellent thermal water binding (<1%). As compared to KFG, PBF showed greater (P < 0.05) hardness, chewiness, penetration force, gel strength, extrusion force and work of extrusion. These differences were minimized after grinding. Kramer shear values in KFG were greater (P < 0.05) than in PBF when this was ground to 4 mm, but lower (P < 0.05) at 8 mm. The highest Kramer shear values (P < 0.05) were recorded in PTF irrespective of the degree of disintegration. Rheological analyses indicate that the behaviour of KFG, which is thermally stable, is predominantly elastic during heating and exhibits rheological thermal behaviour (at over 40 °C) similar to that of pork backfat.

Commentary on: Treatment of Cellulite Using a 1440-nm Pulsed Laser With One-Year Follow-Up: Preliminary Report

In my opinion, there are four holy grails of cosmetic surgery that the baby boomer generation has been actively pursuing over the last 20 years: noninvasive skin tightening, localized noninvasive fat reduction, stretch mark improvement, and treatment of cellulite. In his study, Dr. DiBernardo introduces an interesting, novel, and promising new approach to the last of these goals. As the author points out, his study is limited by a small number of patients (10). However, this study is well designed as a prospective controlled model. The clear strengths of the study include the full year of follow-up, the clearly-demonstrated photographic improvement, and the objective measurements of skin elasticity and thickness. One of the most confusing areas of laser surgery is the area of optimal wavelength utilization. Anderson et al outlined the optimal wavelengths for fat absorption.1 However, that study actually outlined fat absorption from external laser radiation and did not examine the effectiveness of absorption when the laser was fired into the hypodermis in direct contact with the fat itself. Many wavelengths are utilized in the melting of fat (eg, 920 nm, 975 nm, 1064 nm, 1320 nm, and 1440 nm), and the characteristics of each are beyond the scope of this commentary. However, the 1440-nm wavelength—the one administered in Dr. …

Milk fatty acid composition and cheese texture and appearance from cows fed hay or different grazing systems on upland pastures

The objective of this work was to compare milk fatty acid (FA) profile and texture and appearance of Cantal cheeses obtained from cows grazing 2 different upland grasslands: a highly diversified pasture (74 species) of area 12.5 ha managed under continuous mode (C), and a weakly diversified pasture (31 species) of area 7.7 ha (an old temporary grassland) managed under rotational mode (R). A control group of cows fed a hay-based diet (indoors, I) was used. Three equivalent groups of 12 Montbéliarde cows underwent the 3 treatments from May to September 2008. The cheeses were manufactured during 3 consecutive days in early June, early July, and late August (27 cheeses in all). The texture, appearance, and chemical composition of the cheeses were determined after 12 wk of ripening. Concentrations of total saturated FA and monounsaturated FA were higher and lower, respectively, in I milks compared with pasture milks. The concentrations of trans-11-C18:1 and cis-9-C18:1, and polyunsaturated FA as well as yellowness decreased during the season in C-derived milk but remained constant in R-derived milk, through a combined effect of grass development stage and the cows’ grazing selection. The I cheeses were, on average, firmer, less creamy, less elastic, and less yellow than the pasture cheeses. Decreasing and increasing trends in texture firmness during the season were observed for C and R cheeses, respectively. The rind of the pasture-fed cow cheese had fewer, less intensely colored, and less prominent spots than did that of I cheeses. This difference was probably due to greater migration of fat to the rind during pressing because of the lower fat melting point of the pasture-fed cow cheeses, which had higher unsaturated FA content. The greater amounts of fat deposited on the rind of the pasture-fed cow cheeses may have partially inhibited the microbial activity responsible for rind appearance. Our trial underlines the importance of the effects of grazing management associated with vegetation type on milk and cheese characteristics.

Modeling Transport in Porous Media With Phase Change: Applications to Food Processing

Fundamental, physics-based modeling of complex food processes is still in the developmental stages. This lack of development can be attributed to complexities in both the material and transport processes. Society has a critical need for automating food processes (both in industry and at home) while improving quality and making food safe. Product, process, and equipment designs in food manufacturing require a more detailed understanding of food processes that is possible only through physics-based modeling. The objectives of this paper are (1) to develop a general multicomponent and multiphase modeling framework that can be used for different thermal food processes and can be implemented in commercially available software (for wider use) and (2) to apply the model to the simulation of deep-fat frying and hamburger cooking processes and validate the results. Treating food material as a porous medium, heat and mass transfer inside such material during its thermal processing is described using equations for mass and energy conservation that include binary diffusion, capillary and convective modes of transport, and physicochemical changes in the solid matrix that include phase changes such as melting of fat and water and evaporation/condensation of water. Evaporation/condensation is considered to be distributed throughout the domain and is described by a novel nonequilibrium formulation whose parameters have been discussed in detail. Two complex food processes, deep-fat frying and contact heating of a hamburger patty, representing a large group of common food thermal processes with similar physics have been implemented using the modeling framework. The predictions are validated with experimental results from the literature. As the food (a porous hygroscopic material) is heated from the surface, a zone of evaporation moves from the surface to the interior. Mass transfer due to the pressure gradient (from evaporation) is significant. As temperature rises, the properties of the solid matrix change and the phases of frozen water and fat become transportable, thus affecting the transport processes significantly. Because the modeling framework is general and formulated in a manner that makes it implementable in commercial software, it can be very useful in computer-aided food manufacturing. Beyond its immediate applicability in food processing, such a comprehensive model can be useful in medicine (for thermal therapies such as laser surgery), soil remediation, nuclear waste treatment, and other fields where heat and mass transfer takes place in porous media with significant evaporation and other phase changes.

Quantitative trait loci for organ weights and adipose fat composition in Jersey and Limousin back‐cross cattle finished on pasture or feedlot

A QTL study of live animal and carcass traits in beef cattle was carried out in New Zealand and Australia. Back-cross calves (385 heifers and 398 steers) were generated, with Jersey and Limousin backgrounds. This paper reports on weights of eight organs (heart, liver, lungs, kidneys, spleen, gastro-intestinal tract, fat, and rumen contents) and 12 fat composition traits (fatty acid (FA) percentages, saturated and monounsaturated FA subtotals, and fat melting point). The New Zealand cattle were reared and finished on pasture, whilst Australian cattle were reared on grass and finished on grain for at least 180 days. For organ weights and fat composition traits, 10 and 12 significant QTL locations (P<0.05), respectively, were detected on a genome-wide basis, in combined-sire or within-sire analyses. Seven QTL significant for organ weights were found at the proximal end of chromosome 2. This chromosome carries a variant myostatin allele (F94L), segregating from the Limousin ancestry, and this is a positional candidate for the QTL. Ten significant QTL for fat composition were found on chromosomes 19 and 26. Fatty acid synthase and stearoyl-CoA desaturase (SCD1), respectively, are positional candidate genes for these QTL. Two FA QTL found to be common to sire groups in both populations were for percentages of C14:0 and C14:1 (relative to all FAs) on chromosome 26, near the SCD1 candidate gene.

Cheese-Matrix Characteristics During Heating and Cheese Melting Temperature Prediction by Synchronous Fluorescence and Mid-infrared Spectroscopies

The structure and rheology characteristics of Comte (hard cheese) and Raclette (semihard cheese) cheeses as a function of temperature were investigated using dynamic testing rheology and mid-infrared and synchronous front-face fluorescence spectroscopies. The storage modulus (G′), the loss modulus (G″), and the complex viscosity (η*) decreased while strain and phase angle (tan δ) increased as the temperature increased from 20 to 80 °C. SF (250–500 nm with Δλ = 80) and MIR (3,000–2,800 (fat region), 1,700–1,500 (protein region), and 1,500–900 cm−1 (fingerprint region)) spectra were recorded on cheese samples at 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, and 80 °C. The results showed that each spectroscopic technique provided relevant information related to the cheese protein and fat structures during melting, allowing the investigation of structural changes. In addition, the melting temperatures of cheese matrices and fats of the two cheeses were determined from the dynamic rheology data, SF spectra, and MIR spectra. Similar temperatures were obtained whatever the technique, since values of about 60 and 31 °C were obtained for matrix and fat melting temperatures of Comte and Raclette cheeses, respectively. No significant difference was observed between the results obtained with the three methods (significance level of 5%).