Effects of Chopping Temperature on the Microstructure of Meat Emulsions

A standard frankfurter formulation (25% fat) was used to evaluate the effects of four endpoint chopping temperatures (10, 16, 22 and 28°C) on the ultrastructure of meat emulsions with a grind-mix-emulsify production system. Scanning electron microscopy (SEM) was used to evaluate the changes that occur in the ultrastructure of a meat emulsion. Thermally processed frankfurters from each of the four endpoint chopping temperature treatments were fractured, fixed, dehydrated, critical point dried, and coated with Au/Pd before SEM micrographs were taken. Micrographs suggest that maximal emulsion stability is attained as a tradeoff between two different functions. The first function is related to the interfacial protein film thickness and the second function is related to the integrity and density of the surrounding emulsion matrix, and its ability to retain that integrity during thermal processing. These two functions appear to be directly related to the fat-holding and water-binding abilities of the meat emulsion or batter.     

Effects of Thermal Sensitivity of Fish Proteins from Various Species on Rheological Properties of Gels

ABSTRACT: Thermal sensitivity of myofibrillar proteins from various fish species were compared at various preincubation (setting) treatments and chopping temperatures. There was a significant species effect on gel texture by both pre‐incubation and chopping temperatures. Whereas Alaska pollock had the highest shear stress values at 5 °C or lower temperatures, big eye, lizardfish, and threadfin bream had higher fracture shear stress values at 25 °C or higher temperatures. Decreased intensity of myosin heavy chain (MHC) for warm‐water species set at 40 °C clearly revealed higher thermal stability of these particular species.     

Optimum chopping conditions for Alaska pollock, Pacific whiting, and threadfin bream surimi paste and gel based on rheological and Raman spectroscopic analysis

Rheological and Raman spectroscopic properties of surimi from three species [Alaska pollock (AP) (cold water), Pacific whiting (temperate water), and threadfin bream (warm water)] were investigated as affected by various chopping conditions. Comminuting Alaska pollock surimi at 0 °C demonstrated superior gel hardness and cohesiveness when chopping time was extended to 15-18 min; however, long chopping time at higher temperatures resulted in a significantly decreased gel texture particularly at 20 °C. Warm water fish threadfin bream exhibited higher gel texture when chopping was done longer at higher temperature. Rheological properties were significantly affected by both chopping time and temperature. Species effect, based on their thermal stability, was readily apparent. Raman spectroscopy revealed a significant change in disulfide linkage and the reduction of secondary structure upon extended chopping. Dynamic oscillation rheology demonstrated the damage of light meromyoisn and lowering of onset of gelling temperature as the chopping time was extended. PRACTICAL APPLICATION: Chopping conditions to determine gel quality and manufacture surimi seafood are varied by all manufacturers. This paper covering three primary species for surimi with their suggested optimum chopping conditions: 15 min for Alaska pollock when chopped at 0 °C, 15 min for Pacific whiting at 15-20 °C, and 18 min for threadfin bream at 25-30 °C. The use of optimum chopping condition should maximize the value of each surimi and provide consistent quality to the end users.     

Comparison of the Thermostability of Red Hake and Alaska Pollock Surimi during Processing

Thermostability of red hake (Vrophycis chuss) mince and its temperature-dependent gel-forming properties were determined while using Alaska pollock (Theragra chalcogrumma) for comparison. Fish mince and surimi were subjected to various washwater, chopping and setting/ cooking temperatures, cooking times at varying salt concentrations and moisture levels. The optimal temperatures for washing and chopping were 15°C and 12°C for red hake and 10°C and 4°C for pollock, respectively. All treatments significantly affected gel properties. For red hake gels, 77% moisture, 2.0% salt, and a 40°C preheat-setting temperature produced the most cohesive gel. Gels of both red hake and pollock gradually became less cohesive with extended cooking time. The results suggest that red hake is more thermally stable than pollock.     

Effect of Heating Temperature and Muscle Type on Porcine Muscle Extracts as Determined by Reverse Phase High Performance Liquid Chromatography

Samples from porcine longissimus muscles were heated to temperatures ranging from 40–80°C to reach endpoint temperatures (0 min) or held at endpoint temperature for 30 min. Proteins in water-soluble extracts of these samples were separated and quantified by reverse phase high performance liquid chromatography (RP-HPLC). After heating to 60°C for 0 min or to 55°C and holding for 30 min, lactate dehydrogenase (LDH), pyruvate kinase (PK) and myoglobin appeared to comprise the bulk of the remaining soluble protein. RP-HPLC analysis of water soluble extracts from longissimus dorsi, serratus ventralis and psoas major muscles from barrows and sows indicated differences in proportions of LDH and myoglobin.     

DSC study on the influence of meat source, salt and fat levels, and processing parameters on batters pressurisation

 Hydrostatic high-pressure/temperature treatments were conducted at low (10 °C) and high temperatures (60, 70, and 80°C) on different types of meat batters. Pressure-induced effects on proteins were intensified by sodium chloride molarity at low and high temperatures. Treatments at 10°C under pressurisation yielded net thermal destabilisation effects on meat proteins pertaining either to muscle or batter systems. Heating at usual cooking temperature of 70°C under pressure yielded net stabilising effects on meat batter proteins. Overheating at 80°C was needed for entire protein denaturation. Pork and chicken meats were very similar in behaviour but chicken batters exhibited relatively higher thermal- and pressure-induced protein denaturation. Both kinds of physical destabilisation/stabilisation of proteins by pressure-induced effects increased with pressure level. Received: 30 December 1999 / Revised version: 14 February 2000     

Modelling the yield and texture of comminuted pork products using color and temperature. Effect of fat/lean ratio and starch

Practices to control the processing of finely comminuted meat products are proposed. The objective was to test the practical value of both temperature and light reflection measurements made during emulsification as potential indicators of cooking losses and resulting gel texture in pork sausages emulsified within a wide range of temperatures and starch and fat levels. Prior to cooking, pork batters were chopped for different times to ensure final emulsion temperatures ranging from 5 to 50°C. The effects of the fat/lean ratio (0.25 and 0.67) and starch addition (0.8 and 3.2% w:w) on temperature and optical reflection were also investigated. The chopping increased the temperature and decreased the light reflection of fresh meat emulsion. There was no relevant loss of emulsifying capacity at emulsion temperature below 30°C and lightness values over 70 CIE units. The losses and textural parameters of cooked emulsions could be predicted by means of non-linear regression equations based on the temperature and color of the raw emulsion. The determination coefficients obtained ranged from 0.89 to 0.99. The prediction models needed to be fitted to each batter formulation, especially in the presence of reduced levels of gelation agents (meat protein and starch). Lightness was a better predictor than chromaticity, since it decreased constantly with chopping in the range of final emulsion temperatures studied (5-50°C). This confirms previous studies that lightness could be used for monitoring emulsion stability in meat batters.     

Biochemical characterisation of Alaska pollock,Pacific whiting,and threadfin bream surimi as affected by comminution conditions

Salt-soluble protein, surface reactive sulfhydryl content, and surface hydrophobicity of Alaska pollock, Pacific whiting, and threadfin bream surimi were characterised, as affected by various comminution conditions. Chopping time/temperatures were explored in consideration of their habitat temperatures. Salt-soluble protein (SSP) significantly decreased when chopping time was extended. Corresponding to our follow-up study, no relationship between SSP and gel texture was found. Surface hydrophobicity was inversely proportional to SSP concentration, indicating the unfolding of protein upon comminution. Alaska pollock surimi demonstrated aggregation during chopping at 10 and 20 °C, based on the surface hydrophobicity. Surface reactive sulfhydryl (SRSH) contents of the three fish species behaved differently. The SH groups were oxidized to disulphide bonds when higher chopping temperature was applied. As a result, increased SRSH content was not observed in Alaska pollock (10 and 20 °C chopping) and threadfin bream paste (25 and 30 °C chopping).     

Protein-Protein Interaction and Fat and Water Binding in Comminuted Flesh Products

The possible role of protein-protein interaction in influencing the water and fat binding capacity of comminuted flesh products was studied. Water and fat binding by meat batters diminish when temperatures exceed 16°C during comminution. The loss of binding capacity was partially reversible, and cooling the batters to 0°C by addition of dry ice and rechopping allowed a partial recovery of the fat and water binding capacity. A cause and effect relationship between the change in fat and water binding by meat batters on chopping and protein-protein interaction in actomyosin solutions was demonstrated. Protein-protein interaction results in molecular aggregation and when measured as an increase in light scattering absorbance at 320 nm by a protein solution, the reaction was shown to be reversible between 4 and 30°C. When actomyosin solutions extracted from meat samples showed reduced protein-protein interaction in the temperature range used in chopping, the batters made from these meats also showed the least loss in fat and water binding capacity with prolonged chopping. Controlling temperatures during chopping within a range where protein-protein interaction in actomyosin solutions was found to be minimal, allowed prolonged chopping without loss in fat and water binding.     

Shelf Life of Shrimp (Penaeus merguiensis) Stored at Different Temperatures

The sensory, microbiological and biochemical changes were determined in shrimp (Penaeus merguiensis) stored at 0° to 35°C. Mean aerobic plate count of fresh shrimp, initially 5.0 × 10⁵ CFU/g, increased with time and temperature to 6.4 × 10⁹ CFU/g at 35°C after 24 hr. A total of 560 different bacteria were isolated and identified. In addition, the dominant organisms were tested for ability to reduce TMAO, produce indole and hydrolyze protein. The initial bacteria were 30% Gram + organisms but changed to predominantly Grampsychrotrophs at lower temperatures and to mesophiles at higher temperatures. Odor, texture and color qualities decreased; TMA, TVB, pH and Indole increased with time and temperature. Shelf life of shrimp ranged from 7 hr at 35°C to 13 days at 0°C.     

Effect of Gradual Heating and Fat/Oil Type on Fat Stability,Texture, Color,and Microstructure of Meat Batters

The effects of endpoint cooking temperature (40, 50, 60, 70, 80, and 90 °C) on emulsion stability, texture, color, and microstructure of meat batters prepared with different fats/oils were studied. Canola oil treatments showed the highest cooking loss whereas hydrogenated palm oil provided the most stable meat batters. Rendered beef fat was less stable than regular beef fat. Increasing endpoint cooking temperatures resulted in a progressive reduction of water holding capacity in all treatments. As temperature was raised, meat batters showed higher hardness and cohesiveness values, but no appreciable changes in cohesiveness above 60 °C. Canola and hydrogenated palm oil treatments showed the highest hardness and chewiness values. Lightness (L^*) values of all meat batters increased significantly with increasing temperature from 40 to 60 or 70 °C; no major changes observed above 70 °C. Light microscopy revealed no substantial changes in the microstructure of all the stable meat batters cooked to between 50 and 70 °C. Heating to 90 °C changed the microstructure in all meat batters except the hydrogenated palm oil treatments, which still showed nonround fat particles and a less aggregated protein matrix.     

Influence of technological parameters on the structure of the batter and the texture of frankfurter type sausages

The aim of the study was, on the one hand, to determine the relationships between various technological factors, the structure of the batters and the texture characteristics of frankfurter type sausages, and, on the other, to define the possibilities of realizing a reference scale for texture. The addition of sodium chloride in the 0-2% range induces a large increase (60%) in the cooking yield, a decrease in the specific gravity and an increase in the viscosity of the batter determined indirectly through the evolution of the product temperature during chopping. These variations together, give a 30% decrease in the mechanical firmness and a 100% and 90% increase in the juiciness and elasticity of the final products, respectively. However, beyond 2%, sodium chloride does not induce any significant effect on these characteristics. The addition of caseinate in a 1-3% range induces a degassing of the batter and a 10-37% decrease in the water losses during cooking. The higher the caseinate content in the 0-6% range, the larger the rise in the batter temperature during chopping. Sausages are also considered harder (+22%) and less juicy and elastic (-50%) when caseinate content increases. Addition of 0·1-0·5% polyphosphates and chopping under vacuum (0·2 atm) induce variations in the cooking yield, +3% and -1%, respectively, but have no influence on the texture of the final products. Modifications of all these technological parameters induced variations by a factor of 2 in the different mechanical parameters and in parallel differences of 1-2 points on a 6 point scale for sensory characteristics.     

Textural properties and water-holding capacity of broiler breast meat cooked to various internal endpoint temperatures

A total of 100 broiler breast meat was cooked at 176°C to internal temperatures of either 71, 73, 75, 77, or 79°C. Tenderness significantly decreased as internal temperatures increased. The decrease was most pronounced at 79°C with a 26.4% increase in Meullenet-Owens-Razor-Shear (MORS) energy compared to that at 71°C. The toughness-temperature coefficient (TTC, change in tenderness/1°C increase) was calculated to be 4.48% across the temperature ranges. Cooking loss increased constantly with the increase of internal temperatures and ranged from 15 to 27% across the range of endpoint temperatures. Poultry breast meat cooked to a higher internal temperature was in average less tender and also more variable in tenderness.     

Formulation and Copping Temperature Effects on Beef Frankfurters

Frankfurters were manufactured using four fat and added water (AW) formulations (10% fat/30% AW; 15%/25%; 20%/20%; 30%/10%) and processed at chopping temperatures 9, 12, or 15°C. The batters were stuffed into cellulose casings, thermally processed, chilled and vacuum-packaged. Frankfurters were analyzed for proximate composition, textural properties and purge. No differences occurred among treatments for processing yield (89.8%± 1.83). Frankfurters chopped to 12°C had the highest (P < 0.05) Kramer peak force values. As expected, purge increased in all treatments as storage time increased (P < 0.05). As AW increased, hardness and cohesiveness decreased and purge increased. Water level and fat reduction were the most critical factors affecting quality.     

Electrical Stimulation of Mutton

Electrically stimulated ovine muscles, restrained from shortening during rapid chilling at 0-1 or 15-16°C, had lower Warner-Bratzler (WB) shear force values after 1 and 2 days aging at 0-1°C than un-stimulated controls, but were not significantly different at ≥4 days aging. Direct measurement of muscle fiber length showed that contraction values obtained for muscles assigned to go into rigor at 0, 15, 30 or 40°C were significantly less for stimulated muscles than for control muscles at 0°C, but of same magnitude or at rigor temperatures ≥15°C. WB shear force values indicated that, at temperatures ≥15°C, increase in tenderness due to stimulation became small after 7 days aging at 0-1°C, whereas at 0°C aging further increased improvement due to stimulation. Results were thus consistent with electrical stimulation reducing myofibrillar shortening at rigor temperature <15°C but at temperature ≥15°C stimulation had the same effect as a few days aging.     

Effects of Collagen and Alkaline Phosphate on Time of Chopping, Emulsion Stability and Protein Solubility of Fine-Cut Meat Systems

Four meat emulsions were prepared with two levels of collagen and alkaline phosphate. Samples were taken at five different chopping temperatures and evaluated for total chopping time, emulsion stability and protein solubility. Adding additional collagen to meat emulsions shortened total chopping time, and decreased emulsion stability but had no effect on protein solubility. The addition of 0.25% sodium tripolyphosphate (STPP) improved emulsion stability but resulted in no significant (p>0.05) change in chopping time or protein solubility. The high-collagen-phosphate (HCP) treatment resulted in less fat, gelliquid, solid and total cookout when compared with high-collagen no-phosphate (HC) and low-collagen no- phosphate (LC) treatments. Maximum emulsion stability was obtained at 13°C.     

Effect of Gums on Low-Fat Meat Batters

The effects of adding Iota-carrageenan, kappa-carrageenan, guar gum, locust bean gum, xanthan gum, methylcellulose, and a locust bean gum/kappa carrageenan mixture to low-fat, high moisture meat batters were investigated. The methylcellulose treatment showed an increase in weight losses between 60° and 70°C, while other treatments remained similar throughout heating. Xanthan gum and guar gum at 0.2% altered textural parameters as determined by texture profile analysis. Increasing the concentration of xanthan gum decreased batter hardness without affecting batter stability. Sensory evaluation indicated that low-fat frankfurters (11–12% fat) were as acceptable as control frankfurters (27% fat).     

斩拌初始温度对白鲢鱼糜物理特性的影响

斩拌是鱼糜制品生产中最重要的工序之一。以生鲜鱼糜和冷冻鱼糜为原料,考察加工过程中斩拌初始温度对生鲜鱼糜凝胶和冷冻鱼糜凝胶强度、保水性、折曲实验及色度的影响。结果表明：从凝胶强度的观点看,生鲜鱼糜斩拌适宜初始温度为5～15℃,从保水性的观点看,适宜初始温度为5～20℃;而冷冻鱼糜的适宜温度范围分别在1～15℃和5～20℃。综合考虑,5～15℃为鱼糜的最适斩拌初始温度。     

Effect of Different Processing Methods and Salt Content on the Physicochemical and Rheological Properties of Meat Batters

The physicochemical and rheological properties of raw and cooked batters produced by a chopping or beating process with various amounts of salt content were studied. Various meat batters were made up for this purpose: the batter processed by chopping with 2% salt, by beating with 1% salt and 2% salt, respectively. Compared with the chopping, the beating cooked batters had higher L* value, hardness, G’ value at 80°C, and lower cooking loss. Using the beating process, the batter with 1% salt had lower L* values, hardness, springiness, and higher cooking loss than the 2% salt. From the micrographs, the batters produced by beating process exhibited more uniform and compact microstructure than the chopping. The result of low-field nuclear magnetic resonance exhibited that the batters of beating had higher water holding capacity than the chopping. Overall, the beating process enabled lowering of the salt content, cooking loss, and making the cooked batter more hard and elastic.     

The effects of low mixing temperature on dough rheology and bread properties

In this research, the effects of a low mixing temperature on dough rheology and the quality of bread were investigated. In the experiments, strong flour samples (Type 550), 1.5% salt, 3% of yeast and 1% additive mixture were used and dough samples were mixed at 17 °C (low temperature), 23 °C (control) and 30 °C (high temperature). Five different periods (0, 30, 60, 90 and 120 min) were applied at the bulk fermentation stage. At the final proofing stage, the dough was fermented until it reached a constant height. It was determined that almost every bread from dough samples mixed at 17 °C resulted in not only the highest bread volume and bread weight, but also the best texture, elasticity and crumb structure. The results of dough samples mixed at 23 °C were worse than those of dough samples mixed at 17 °C. The worst results were obtained from dough samples mixed at 30 °C (high temperature). As a result, it may be concluded that the quality of bread from dough samples mixed at low temperature (17 °C) is superior to those from dough samples mixed at the higher temperatures. Besides these findings, it may also be stated that prolonging the period of bulk fermentation in dough samples mixed at 17 °C positively develops baking performances.