EFFECTS OF TYPES AND LEVELS OF FAT AND RATES AND TEMPERATURES OF COMMINUTION ON THE PROCESSING AND CHARACTERISTICS OF FRANKFURTERS

ABSTRACT— Frankfurter emulsions containing either 25% or 35% beef fat, pork fat, or cottonseed oil were prepared by comminuting at 1500, 2500, or 5000 rpm to temperatures ranging from 45°–85°F. Data were obtained on the viscosities of the emulsions; except for initially high viscosities for which unmelted fat was responsible, the viscosities of emulsions containing the fats, or oil, were similar: viscosities tended to decrease with increasing time and temperature of chopping. The frankfurters were stuffed, smoked, and cooked, and data were obtained on shrinkage, fat retention, ease of peeling, specific gravity, and texture. Shrinkage was inversely related to content of fat. Fat separation mainly occurred in processing frankfurters containing beef fat; the data suggest that emulsions containing beef fat should be comminuted to 65°–75°F to avoid possible under or overchopping: the results show that optimum conditions were time as well as temperature dependent. The air content of frankfurters varied inversely with the maximum temperature attained during communition. Frankfurter skin strength was lessened on increasing the temperatures to which emulsions were communited; elasticity, the equivalent of rubberiness, decreased under these conditions.     

EFFECT OF RHEOLOGICAL INTERRELATIONSHIPS BETWEEN STARCH GEL AND FAT ON THE FAT DISPERSION IN FARINACEOUS GEL MATRIX

The rheological interrelationships between starch gel and fat clearly affected the fat dispersion pattern in the farinaceous matrix when soybean-oil-based plastic fat was dispersed in modified tapioca starch gel. A gradual increase in fat particle size with concomitant decrease in fat particle numbers (=0.95) was seen as both viscosity and rigidity of starch gel were decreased. The fat particle size gradually got larger with an increase in fat hardness and began to increase sharply as the fat reached its plastic range (30–40% solid fat). The fat particle size was markedly reduced as both the starch gel to fat viscosity ratio and the shear rate were increased. The viscosity of fat-starch gel mix was highly correlated with fat particle size (r=0.95). The fat viscosity, the rigidity of gel matrix, and the shear rate applied during dispersion appeared to be the most important rheological parameters which determine the overall dispersion pattern of fat in the farinaceous gel matrix.     

EFFECTS OF AN AUTOLYZED YEAST ON PHYSICAL AND SENSORY PROPERTIES OF FRANKFURTERS

Three experiments were conducted to determine effects of autolyzed yeast on frankfurter firmness, flavor, and yields. Smokehouse yields of laboratory prepared frankfurters (Experiment #1) were not affected (P < 0.05) by addition of autolyzed yeast (1%). Commercially produced frankfurters containing 0%, 1.0%, or 1.5% yeast (Experiment #2) or 0%, 0.75% or 1.0% yeast (Experiment #3) were subjected to sensory and yield evaluations. Frankfurters from Experiment #2, with 1% autolyzed yeast were more firm (P < .10) than control frankfurters. Frankfurters from Experiment #3 with 0.75% and 1.0% autolyzed yeast were more firm (P < .01, P < .10) than controls. Vacuum packaged frankfurters containing yeast (Experiments #2 and #3), held 2, 4, or 6 weeks at 2–5°C, had less purge than their respective controls. Autolyzed yeast appeaers to enhance frankfurter flavor and firmness while reducing purge in vacuum packaged product.     

THE EFFECTS OF LIPIDS AND RELATED MATERIALS ON BEER FOAM

The magnitude of the effect of lipid material on beer foam is not only related to the concentration but also depends on the physical state of lipid in the beer. Several lipid and lipid-like materials have been examined and in all cases lipid added to beer a short time before foaming has a much more harmful effect on the foam than does the same concentration of lipid added some time previously. An explanation is proposed. The relevance to the brewer of these findings is discussed.     

PRELIMINARY OBSERVATIONS ON EFFECTS OF FAT CONTENT AND DEGREE OF FAT EMULSIFICATION ON THE STRUCTURE-FUNCTIONAL RELATIONSHIP OF CHEDDAR-TYPE CHEESE

Cheddar type cheeses of different fat contents were produced and denoted: full-fat (FFC), 306g/kg; half-fat (HFC), 174 g/kg; and low fat (LFC, 13 g/kg). Full-fat Cheddar cheese (FFCH) was also prepared from milk which had been homogenized at first and second stage pressures of 25 and 5 MPa, respectively. The cheeses were held at 4C for 30 days and at 7C for the remainder of the 190-day ripening period. Reducing the fat level from 174 to 13 g/kg resulted in decreases in contents of moisture in nonfat substance and pH 4.6 soluble N as a percentage of total N (pH4.6SN), and increases in the contents of moisture, protein and intact casein. Homogenization of cheesemilk resulted in a slight increase in moisture content and an increase in pH4.6SN. Confocal laser scanning microscopy revealed that the extent of fat globule clumping and coalescence in both the unheated and heated (to 95C) cheeses decreased with homogenization of the cheesemilk and with fat reduction. Homogenization of the cheesemilk and reducing the fat content of the cheese resulted in a decrease in the flowability and stretchability of the melted cheese. Dynamic measurement of the viscoelastic changes on heating the cheese from 20 to 90C showed that reduction of fat content resulted in a decrease in the magnitude of the phase angle, δ, at temperatures >50C. At temperatures<∼60C, the storage modulus, G', increased on reducing the fat content from 306–174 g/kg to 13 g/kg. Homogenization resulted in a marked decrease in δ at temperatures>45–50C, with δ_max typically decreasing from ∼65–70° in the FFC to ∼35° in the FFCH.     

THE EFFECTS OF INCREASED STEEPING TEMPERATURES ON ENZYME DEVELOPMENT IN MALT

Malts produced by steeping at 30 °C for a total of 24 h including two air rests, frequently give the same results in routine analyses as do malts produced by steeping at 16°C for longer periods. However, the corresponding worts often filter more slowly under controlled laboratory conditions. The increased steeping temperatures can delay or reduce development of endopeptidase and β-glucan solubitase, but generally have little effect on the activity of α-amylase, carboxypeptidase, or endo-β-glucanase. The problems with wort separation are most probably due to high molecular weight β-glucan and disulphide-linked hordein persisting at the end of malting.     

EFFECT OF TOTAL LIPIDS, TRIACYLGLYCEROLS AND PHOSPHOLIPIDS ON MALONALDEHYDE CONTENT IN DIFFERENT TYPES OF CHICKEN MUSCLES AND THE CORRESPONDING SKIN

Total lipid extracted from chicken breast, thigh, drumstick and wing muscles and the corresponding skin was analyzed for triacylglycerols and phospholipids as well as their fatty acid composition and also for malonaldehyde and lipid oxidation fluorescent products (LOFP) content.
Muscles consist of only 1.2–3.2% lipid, but lipid concentration in the skin ranges from 22.2–31.7%. The percentage of phospholipid in muscle lipid was 20 times more than that of the skin. The fatty acids of triacylglycerols from muscles and skin contained less than 2% of polyunsaturated fatty acids (PUFA). Fatty acids from phospholipid of the meat contained over 15% arachidonic acid and substantial amounts of PUFA with 22 carbon atoms. Skin phospholipid had 10.6–13.2% of all PUFA.
Differences in the lipid composition of muscles and skin resulted in a concentration of malonaldehyde in muscle lipids of 30–50 mg/g, a value more than 15 times greater than in lipids of the skin. However, the TBA number of the skin was the same or a little bit lower as compared to muscles. The relative levels of LOFP in the organic phase of Folch-extracted muscle and skin tissues paralleled the trend found for malonaldehyde concentrations.
It was concluded that the simultaneous determination of total lipid content and malonaldehyde concentration in lipid extracted from various chicken muscles and corresponding skin was the most informative method for evaluation of precursors of lipid oxidation in fresh tissue.     

EFFECTS OF END-POINT TEMPERATURE AND FAT LEVEL ON THE RESIDUAL CHOLESTEROL IN GROUND BEEF PATTIES1

Patties of lean ground beef with 2% fat (L2PF) and 6% fat (L6PF) were used to study the fat and cholesterol composition of raw and cooked ground beef and to determine how the end-point cooking temperature affects the amount of fat and cholesterol in a lean ground beef patty as it would be eaten by the consumer. The two patty types were obtained from the longissimus muscle of steers with marbling scores associated with “Standard” to “Select” and “Select” to “Choice” U.S. carcass grades of beef, respectively. All steers were fed a diet of roughage and concentrates to ensure fat deposition over the 12th and 13th ribs; longissimus muscles between the 7th and 10th ribs were removed, trimmed of all external fat, ground and formed into three 130-g patties. One patty was fried to an internal temperature of 60C, another to 71C and the third was uncooked. After frying, the patties were measured for drip loss, moisture and total fat. The fat extract was used for cholesterol analysis. The cooked L2PF sample had significantly less fat than the cooked L6PF samples, but there was no difference between the L2PF and L6PF in cholesterol. End-point temperature had no effect on the fat and cholesterol contents for either L2PF or L6PF samples, but the higher end-point temperature resulted in a significant loss of moisture.     

EFFECTS OF RAISED TEMPERATURES DURING STEEPING AND GERMINATION ON PROTEOLYSIS DURING MALTING

Raising the temperature from 16°C to 20°C or 25°C for prolonged periods during steeping or germination reduces HWE and TSN and slows down wort separation in laboratory mashes. When the higher temperatures are applied only during the last steep or the first two days of germination the initial rate of modification is accelerated, as is the development of α-amylase and endopeptidase. After four or five days germination the levels of enzyme activity are substantially lower than in the control malt. However, some barleys give malts with acceptable standard analyses after 4 rather than 5 days of germination.     

MICROSTRUCTURE AND TEXTURE OF CHEESE ANALOGS CONTAINING DIFFERENT TYPES OF FAT

The texture of cheese analogs, whose fat fraction was composed of butterfat, soybean oil or soybean fat and their blends was measured by instrumental Texture Profile Analysis (TPA), and sensorially by a trained panel and the results were subjected to Response Surface Methodology (RSM). The microstructure was examined by Scanning Electron Microscopy (SEM). The models showed that the diverse fat types differently influenced the instrumental characteristics of hardness and springiness, and the sensory characteristics of firmness, elasticity, shear resistance, mouthfeel and creaminess of the cheese analogs. Scanning electron micrographs indicated that the morphology, size and distribution of fat droplets also varied with the fat type.     

EFFECTS OF FAT LEVEL AND COOKING METHODS ON PHYSICAL AND SENSORY CHARACTERISTICS OF RESTRUCTURED BEEF STEAKS

Trimmed top rounds from 9 Angus steers were flaked and formed into restructured steaks containing 15, 20, or 25% fat. The steaks were cooked in a microwave oven (MW) on a preheated browning dish or broiled in a conventional oven (CO). Microwave cooking required less time and energy. Decreased time and energy for cooking also related to increased fat levels. Cooking losses and penetration hardness values were greater for the MW steaks. Cooking losses increased and penetration hardness values decreased with increasing fat level. MW steaks appeared more well-done and were harder, less moist, and more resistant to chewing. As fat level increased softness and moistness scores also increased. Consumer panelists found all steaks to be equally acceptable, suggesting the potential for the development of portion- and fat-controlled restructured steaks for microwave cooking.