Physicochemical Effects of the Lipid Phase and Protein Level on Meat Emulsion Stability,Texture, and Microstructure

ABSTRACT: The effects of beef fat (25%) substitution with rendered beef fat, canola oil, palm oil, or hydrogenated palm oil at varying meat protein levels (8%, 11%, and 14%) were studied in emulsified beef meat batters. There was no significant difference in fat loss among meat batters made with beef fat, rendered beef fat, or palm oil. Hydrogenated palm oil provided the most stable batters at all protein levels. Increasing meat protein to 14% resulted in high fat loss in batters prepared with canola oil, which did not occur in the other formulations. This indicates that the physicochemical characteristics of fat/oil affect emulsion stability. Cooked batter hardness was higher (P < 0.05) when protein level was raised; highest in hydrogenated palm oil batters when compared at similar protein levels. As protein level was raised springiness values were increased in all the meat treatments. Springiness was higher in the canola oil treatments. Light microscopy revealed fat globule coalescence in canola oil meat batters prepared with 14% protein, as well as the development of fat channels and more protein aggregation; both seem to result in lower emulsion stability. Hydrogenated palm oil batters showed fat particles with sharp edges as opposed to the round ones seen in all other treatments.     

Fat reduction in comminuted meat products-effects of beef fat, regular and pre-emulsified canola oil

The effects of fat reduction (25.0%, 17.5%, and 10.0%) and substituting beef fat with canola oil or pre-emulsified canola oil (using soy protein isolate, sodium caseinate or whey protein isolate) on cooking loss, texture and color of comminuted meat products were investigated. Reducing fat from 25 to 10% increased cooking loss and decreased hardness. Canola oil or pre-emulsified treatments showed a positive effect on improving yield and restoring textural parameters. Using sodium caseinate to pre-emulsify the oil resulted in the highest hardness value. Cohesiveness was affected by fat type and level. The color of reduced fat meat batters was darker for all, except the beef fat treatments. Using canola oil or pre-emulsified oil resulted in a significant reduction in redness. The results show that pre-emulsification can offset some of the changes in reduced fat meat products when more water is used to substitute for the fat and that pre-emulsification can also help to produce a more stable meat matrix.     

Effects of protein level and fat/oil on emulsion stability,texture, microstructure and color of meat batters

Beef meat batters formulated with increasing protein level (10–15%) and containing 25% beef fat were compared to batters prepared with 25% canola oil. Emulsion stability of the canola oil treatments was higher (less separation during cooking) at the 10–13% protein level compared to the beef fat treatments. However, above 13% protein this was reversed and the canola oil treatments showed high fat and liquid separation, which did not occur at all in the beef fat treatments. This indicates differences in stabilization of fat versus oil in such meat emulsions. Hardness of the cooked meat batters showed significantly (P < 0.05) higher values when the protein level was raised, and was higher in canola oil than in beef fat meat emulsions at similar protein levels. Products’ chewiness were higher in the canola oil treatments compared to the beef fat emulsions. Lightness decreased and redness increased in canola oil batters as the protein level was raised. The micrographs revealed the formation of larger fat globules in the beef fat emulsions compared to the canola oil meat emulsions. The canola oil treatment with 14% protein started to show fat globule coalescence, which could be related to the reduced emulsion stability.     

Characteristics of low-fat meat emulsion systems with pork fat replaced by vegetable oils and rice bran fiber

The effects of vegetable oils prepared from olive, corn, soybean, canola, or grape seed, and rice bran fiber on the composition and rheological properties of meat batters were studied. Pork fat at 30% in the control was partially replaced by one of the vegetable oils at 10% in addition to reducing the pork fat to 10%. The chemical composition, cooking characteristics, texture properties, and viscosity of low-fat meat batters were analyzed. The moisture, protein, ash content, uncooked and cooked pH values, b^∗-value, hardness, cohesiveness, gumminess, chewiness, and viscosity of meat batters with vegetable oil and rice bran fiber were all higher than the control. In addition, batters supplemented with vegetable oil and rice bran fiber had lower cooking loss and better emulsion stability. Low-fat meat batters with reduced pork fat content (10%) and 10% vegetable oil plus rice bran fiber had improved characteristics relative to the regular fat control.     

Effects of two types of soy protein isolates,native and preheated whey protein isolates on emulsified meat batters prepared at different protein levels

The effects of substituting 1.5% of the meat proteins with low gelling soy protein isolate (LGS), high gelling soy protein isolate (HGS), native whey protein isolate (NWP), and preheated whey protein isolate (PWP) were compared at varying levels of proteins (12, 13 and 14%), with all meat control batters prepared with canola oil. Cooking losses were lower for all the non-meat protein treatments compared to the all meat controls. When raising the protein level from 12 to 14%, cooking losses increased in all treatments except for the NWP treatments. Using LGS increased emulsification and resulted in a more stable meat batters at the 13 and 14% protein treatments. Textural profile analysis results showed that elevating protein level increased hardness and cohesiveness. The highest hardness values were obtained for the PWP treatments and the lowest for the HGS, indicating a strong non-meat protein effect on texture modification. Non-meat protein addition resulted in lighter and less red products (i.e., lower red meat content) compared to the all meat controls; color affected by non-meat protein type. Light microscopy revealed that non-meat proteins decreased the frequency of fat globules' agglomeration and protein aggregation. The whey protein preparations and HGS formed distinct “islands” within the meat batters' matrices, which appeared to interact with the meat protein matrix.     

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     

Reduced Fat, High Moisture Beef Frankfurters as Affected by Chopping Temperature

Six treatment combinations were studied to determine the effects of initial temperature (0, 15, 30°C) and endpoint chopping temperatures (0, 15, 30, 45°C) on texture and stability of reduced fat, high moisture beef frankfurters. Textural properties (raw batter, frankfurter) and purge loss were determined over 8 wk storage. As endpoint chopping temperature increased, batter stability and shear force decreased. In most samples, initial temperature did not affect texture or stability. Endpoint chopping temperatures of ± 15°C resulted in most stable batters. Chopping > 15°C lowered product quality.     

Rapid (microwave) heating rate effects on texture,fat/water holding,and microstructure of cooked comminuted meat batters

Comminuted and gelled, fat-containing meat products such as frankfurters and luncheon meats are commercially processed by heating relatively slowly (for up to 2 h or more) to an endpoint of about 70 °C prior to cooling. This study compared such a slow, ramp heating regime (0.5 °C/min), terminated at 70 °C, to rapid, square-wave cooking (one step: rapid 100 °C/min heating to 70 °C endpoint, plus isothermal holding prior to cooling, or two-step: rapid heating to 50 °C, holding, then rapid heating to 70 °C plus holding prior to cooling) on meat batter gel properties (fracture and small strain rheology, microstructure, cook loss, and expressible water). The results indicated that a rapid cooking process, with its inherent advantages of reduced process time, lower equipment footprint, and more efficient use of energy, can produce a product nearly equivalent in textural properties and cook yield to one processed by traditional smokehouse cooking when the cook value of the processes is similar and an intermediate (near 50 °C) holding step is included (two-step rapid heating). One-step rapid heating negatively affected gel structural homogeneity and water/fat holding properties of fat-containing gels.     

Effects of pre‐emulsifying fat/oil on meat batter stability,texture and microstructure

The effects of pre‐emulsified beef fat and canola oil (CO) (25%) with Tween 80 (T‐80) or sodium caseinate (SC) were studied in beef meat batters prepared at three protein levels (9%, 12% and 15%). Raising meat protein level to 15% resulted in low emulsion stability of products prepared with CO. Using pre‐emulsified beef fat with Tween 80 (BF‐T80) showed significantly higher fat and water losses at all protein levels. There were no differences in fat and water losses between pre‐emulsified beef fat and CO when SC was used at the 9% and 12% protein levels compared to the controls (non pre‐emulsification). Light microscopy revealed fat globule coalescence in the CO meat batters prepared with 15% protein and BF‐T8 treatments, as well as formation of fat channels and more protein aggregation; both resulted in lower emulsion stability. Using SC to emulsify fat/oil produced a finer dispersion of fat globules compared to all the other treatments.     

Replacement of Beef Fat with Partially Hydrogenated Plant Oil in Lean Ground Beef Patties

Partially hydrogenated plant oils (corn, cottonseed, palm, peanut and soybean) were substituted (in part) for beef fat in lean (10% fat) ground beef patties to improve nutrient content of ground beef. Effects of such addition on composition and consumer acceptability were evaluated. Addition of hydrogenated plant oils had little effect on composition of raw or cooked patties. Those containing hydrogenated corn or palm oil were not different (P>0.05) from all-beef patties in cooking loss or overall acceptability. Therefore substitution of hydrogenated oils for beef fat in production of lean ground beef patties may be feasible.     

Frying oils with lower levels of saturated fatty acids induce less heterocyclic amine formation in meat floss (boiled,shredded and fried pork)

Heterocyclic amines (HAs) as potent mutagens are formed in meat floss which is a boiled, shredded and fried traditional meat product. In this study, effects of frying oils (lard, soybean oil and palm oil) on the formation of HAs in meat floss during frying have been investigated. The results showed that the contents of Norharman, Harman, AαC and MeAαC in meat floss that treated with lard and palm oil were higher than soybean oil which contained less saturated fatty acids (P < 0.05). The contents of total HAs in meat floss that treated with palm oil at 150 °C and 180 °C were significantly higher than that treated with soybean oil and lard (P < 0.05). In conclusion, meat floss treated with soybean oil at 120 °C, 150 °C and 180 °C contained lowest levels of HAs and soybean oil could be used as lard substitution to produce healthy meat floss.     

Initial work on developing a cooking protocol for producing re-structured meat under controlled conditions

Restructured meat is made by binding individual pieces of meat together. To study the effect of mechanical work on the meat binding process, a standard cooking protocol must be established. This paper details the establishment of a standard cooking protocol for the cooking process using untreated beef semitendinosus muscle. The effect of different cooking temperatures and applied loads during cooking were investigated. Meat samples were cut in 20 mm cubes size from beef semitendinosus muscle and two pieces were held together with the muscle fibre parallel to each other by wrapping them with a plastic food wrap. Then the samples were placed inside square steel tubes, that act as a mold for cooking, and different weights (0, 250, 500, 750 and 1000 g) were placed on top of the meat cubes during cooking. The temperatures used for cooking were 60, 70 and 80 °C. There was a significant temperature effect, with increases noted between 60 °C and 70 °C and between 70 °C and 80 °C. At 60 °C neither myosin nor collagen has gelatinized, leading to low binding strengths. At 70 °C the myosin component will have gelatinized. At 80 °C the collagen component will be contributing to the bond. To keep the collagen effect to a minimum the meat should be cooked at 70 °C. The effect of applied cooking load was significant at all cooking temperatures once sufficient load had been applied against no load to ensure good contact at the joint. There was a significant effect of applied load noted at 80 °C with increases up to 750 g and a drop occurring between the 750 and 1000 g loadings. The drop has been attributed to collagen being squeezed out of the joint as a bead of white material was noted around the joint.     

High pressure processing of meat batters with added walnuts

Various model systems were designed in order to analyse the way in which addition of different levels of walnut (0, 10, 20%) and processing by high pressure (HPP) (400 MPa for 10 min at 10 °C) influenced the physico‐chemical properties of cooked (70 °C for 30 min) meat batters. The addition of walnut increased the fat level and decreased the moisture content in the meat batters. All of the meat batters exhibited good water and fat binding properties. The hardness, cohesiveness, springiness and chewiness of cooked products were reduced by addition of walnut but were unaffected by HPP. Incorporation of nuts in meat products can potentially be used to confer cardiac health benefits.     

Optimization of replacing pork back fat with grape seed oil and rice bran fiber for reduced-fat meat emulsion systems

The effects of reducing pork fat levels from 30% to 20% and partially substituting the pork fat with a mix of grape seed oil (0%, 5%, 10% and 15%) and 2% rice bran fiber were investigated based on chemical composition, cooking characteristics, physicochemical and textural properties, and viscosity of reduced-fat meat batters. For reduced-fat meat batters containing grape seed oil and rice bran fiber the moisture and ash contents, uncooked and cooked pH values, yellowness, cohesiveness, gumminess, chewiness, and sarcoplasmic protein solubility were higher than in the control samples. The reduced-fat samples with increasing grape seed oil concentrations had lower cooking loss, emulsion stability, and apparent viscosity. The incorporation of grape seed oil and rice bran fiber successfully reduced the animal fat content in the final products while improving other characteristics.     

Effects of pre-heating temperature and formulation on porosity,moisture content,and fat content of fried batters

The effect of pre-heating temperatures on moisture and fat contents, and porosity of fried batters was studied. Batter pre-heated at 60 °C showed higher moisture content, lower fat content and lower porosity than non-pre-heated batter and batters pre-heated at 70 and 80 °C. Moisture content, fat content, and porosity at 4 min frying for batters with different pre-heating treatments ranged from 35.08 to 39.37, 3.92 to 5.16, and 13.14 to 45.31 %, respectively. Because of significant reduction in fat content, 60 °C pre-heating temperature was chosen to study the effect of batter formulations on moisture and fat contents, and porosity. Different wheat to rice flour ratios were prepared, and then each batter was pre-heated at 60 °C. Batters with higher wheat flour content showed higher moisture content, and lower fat content and porosity than batters with higher rice flour.     

Rheological and Stability Transitions in Meat Batters Containing Soy Protein Concentrate and Vital Wheat Gluten

Physical/rheological properties of meat batters during heat-processing were studied. Vital wheat gluten (VWG) and soy protein concentrate (SPC) were incorporated into meat batters which were heated to 40, 50, 60 and 70°C and held for 0, 30 and 60 min. Amounts of fat and aqueous fluid released during heating were determined. A two-cycle compression test and shear modulus determination were used to evaluate rheological changes. VWG and SPC did not have any significant effect on either stability or textural changes. There was a significant interaction between temperature and time for stability and textural characteristics. Significant changes in rheological and stability properties of meat batters occurred in the 50–70°C region. Shear modulus showed a major increase at 54–57°C.     

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.     

Textural Characteristics of Beef: Effects of the Heating System

Textural characteristics of beef semitendinosus roasts heated in 93 and 149°C ovens to 60 and 70°C were compared with those of small samples of semitendinosus heated as cylindrical cores in glass tubes in a water bath. The small samples were heated to the same endpoint temperatures as the roasts were at rates comparable to heating at the two oven temperatures. Cooking losses varied with heating method and in some cases with endpoint temperature and rate of heating. Heating method did not affect the textural parameters of penetration hardness, cohesiveness, and chewiness and shear cohesiveness and firmness. Hydroxyproline solubilization was greater in water bath samples than in intact samples heated at the slower rate. The extent of heat-related changes and their effects on final meat quality partially is determined by the heating system.     

Cooking Treatment, Mixing Time, and Mixing Temperature Affect Pepperoni Cupping

Pepperoni was manufactured using three mixing temperatures (-5, 0, 5°C), three mixing times (2, 8, 14 min) and two cooking treatments (uncooked or cooked to 60°C) to evaluate effects on endpoint textural parameters and cupping of pepperoni. Covariance analysis resulted in higher cohesiveness values and lower cupping scores (P<0.05) for the ?5°C treatments than for the 0 or 5°C mixed treatments. Cooked pepperoni had less diameter shrink (P<0.05) and higher cupping scores (P<0.05) than uncooked treatments. Path analysis (standard partial regression coefficients) showed that diameter and cohesiveness had the greatest direct effects on cupping.     

Chemical, Physical, and Sensory Characterization of Ground Beef Containing 5 to 30 Percent Fat

Ground beef patties containing 5, 10, 15, 20, 25, and 30% fat were evaluated raw and after cooking to either 71 or 77°C. Cooking losses were lowest for 5–20% fat patties (24.7-26.0%), intermediate for 25% fat patties (28.9%), and highest for 30% fat patties (32.1%). Low-fat patties (5 and 10%) were firmer in texture, more crumbly at end-of-chewing, less juicy and flavorful, and caused less oily coating of the mouth than 20–30% fat patties. Warner-Bratzler and Lee-Kramer shear forces decreased as fat increased. Instron texture profile analysis also indicated greater peak forces, springiness, and cohesiveness for low-fat patties. Cooking to 77 vs 71°C accentuated differences in palatability between low- and high-fat patties.