EFFECT OF HEATING METHODS ON THIAMINE RETENTION IN FRESH OR FROZEN PREPARED FOODS

SUMMARY— Thiamine retentions were determined in beef stew, chicken a la f or newburg and peas in cream sauce, which ware 11 freshly prepared and held for 1, 2 or 3 he ld 180°F (82.2°) or 2) freshly prepared, frozen at −10°F (−23.3°C) and reheated to reheated using microwaves, infrared heating or boiling water immersion. Similar treatments had the on the thiamine retention in the various products. The average thiamine retentions Boy de n products (based on 100% for the freshly prepared foods) were 93.5% in the frozen-microwave heated products; 90% in the frozen-infrared heated products; 86% in the frozen-immersion hot products versus 78% in the fresh hot products after 1 hr, 74% after 2 hr and 67% after 3 hr.     

Application of competitive indirect enzyme-linked immunosorbent assay (Ci-ELISA) for monitoring the degree of frozen denaturation of bovine myosin

The denaturation of myosin on freezing and frozen storage was monitored using competitive indirect enzyme-linked immunosorbent assay (Ci-ELISA) formatted with polyclonal antibodies anti-MWM IgG, anti-S-1 IgG and anti-LMM IgG raised against the antigens (Ags) bovine myosin whole molecules (MWMs), heavy meromyosin S-1 (myosin head part, S-1) and light meromyosin (myosin tail part, LMM) respectively. Beef slices and cuts stored at −20 °C or −50 °C lost immune affinity with all antibodies, in particular anti-LMM IgG. Repeated thawing–refreezing treatment caused more myosin denaturation than simple freezing. Myosin from beef stored at −20 °C was denatured more than that stored at −50 °C. The immune affinities between anti-LMM IgG and thawed samples were similar to those from anti-MWM IgG. We were unable to differentiate reliably between fresh and thawed beef using anti-S-1 IgG. Myosin was denatured by freezing, in particular its tail part (LMM).     

A novel fiber optic sensor to monitor beef meat emulsion stability using visible light scattering

Accurate control of the meat emulsification process for a consistent product quality entails the development of an on-line optical sensor technology to determine the optimum chopping end-point yielding minimum cooking loss and a fine texture. Previous studies suggested that light backscatter measurements can be used to monitor physical-chemical changes during emulsification in comminuted meat products if appropriate spacing between the emitting and detecting optical fibers is used. Light backscatter intensity from beef emulsions manufactured with different fat/lean ratio (0.075, 0.250, and 0.330) and chopping duration (2, 5, and 8min) were obtained using a dedicated fiber optic prototype. Optical measurements were collected at three radial distances (2, 2.5, and 3mm) from the light source using a fiber optic spectrometer (300-1100nm). Light backscatter intensity decreased logarithmically with increasing fiber optic spacing. Light propagation through the emulsion decreased significantly with increasing chopping duration and fat concentration. Cooking loss increased with increasing fat/lean ratio and with under- or over-chopping. The maximum emulsion stability was observed at 5min of chopping. Several optically derived parameters were found to be significantly correlated with fat loss during cooking. Typically, those correlations were observed to increase with decreasing fiber distance. Based on these findings, an optical configuration is proposed that would compensate for the emulsion heterogeneity, maximizing the existing correlation between the optical signal and the emulsion quality metrics.     

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.     

LOW-TEMPERATURE DESTRUCTION OF Trichinella spiralis USING LIQUID NITROGEN AND LIQUID CARBON DIOXIDE

The destruction of Trichinella spiralis by low temperature treatment has been demonstrated to be an effective tool in combatting this parasite in fresh pork products. Current procedures, however, require a holding period under varying times and temperatures to accomplish this destruction. Freezing with cryogenic materials offers the opportunity to attain ultra low temperatures and, thus, eliminate post–freezing holding periods. Four trials were conducted using trichina-infected fresh pork patties approximately 9 mm thick and 88 mm square. In trials 1, 2 and 3 the patties were frozen with LN, using a modified Heath freezing tunnel to final equilibrated temperatures of –12C, –14°C, –20°C, –23°C, –25°C, –28°C, –29°C, –39°C and −47°C. In trial 4 the patties were frozen in a Certified Multideck tunnel using liquid CO₂ as a refrigerant to −10°C, –17°C, –23°C, –29°C and –39°C. Patties were thawed immediately and checked for viable T. spiralis. No positive samples were found at temperatures of –29°C or below.     

Morphological changes in tilapia muscle following freezing by airblast and liquid nitrogen methods

The cross-section spacing between the muscle fibre bundles of fresh tilapia chunks was ≈3.06 μm. After freezing by airblast at −20 and −36°C, and by liquid nitrogen at −87 and −128°C at freezing rates of 0.25, 1.53, 9.74 and 19.4 cm h⁻¹, respectively, the spacing increased to 3.21–7.69 μm, which was 5 to 151% greater than that in the fresh samples. The spacing further increased with storage time. Liquid nitrogen freezing resulted in smaller increases in spacing than airblast freezing. On freezing at constant temperatures of −20 to −128°C followed by storage at −20°C for 1 month, the extracellular spacings were 7.38–13.8 μm, and increased to 22.16–29.38 μm after 2 months. After storage at −20°C or −40°C for 6 months, the muscle fibre bundles showed fragmentation in both the airblast and the liquid nitrogen frozen tilapia chunks. The integrity of muscle structure was maintained better with liquid nitrogen freezing than with airblast freezing. All the differences resulting from freezing methods or freezing rates disappeared upon prolonged frozen storage at −20°C or −40°C. The correlations between the freezing temperature and extracellular spacing, and the activation energy (E_a) was calculated. The time required for freezing-temperature-induced differences in crystal growth, or in the extracellular spacing of muscle fibre bundles to disappear when E_a= 0 can be considered as the high-ultrastructural quality shelf-life, which is predicted to be 2.7 months at −20°C for tilapia frozen with liquid nitrogen.     

Freezer Burn of Animal Tissue. 7. Temperature Influence on Development of Freezer Burn in Liver and Muscle Tissue

SUMMARY: Various treatments found previously to affect the development of freezer burn at −10°C (Kaess et al. 1962a, 1967a,b) were applied to slices of beef liver and muscle stored at −20°C. While the general pattern of the development of freezer burn was similar to that obtained at −10°C, evaporative weight losses needed to produce a definite intensity of burn were significantly lower at −20°C. Although less freezer burn developed in low fat livers than in high fat livers at −10°C, fat content had no influence at −20°C. The layer of condensed cells at the evaporating surfaces was thinner at −20°C than at −10°C. Immersion of the tissues in solutions of glycerol or sodium chloride before freezing was effective in controlling freezer burn except with muscle slices cut across the fibers. In similar experiments carried out at −4°C desiccation of the tissue always resulted in the formation of the characteristic condensed layer at the surface but no ireezer burn developed.     

Effect of Temperature (−5 to 130 °C) and Fiber Direction on the Dielectric Properties of Beef Semitendinosus at Radio Frequency and Microwave Frequencies

ABSTRACT:  The dielectric properties must be defined to design efficient radio frequency (RF) and microwave (MW) processes by the food manufacturers. The objective of this study was to understand how frequency, temperature, and muscle fiber orientation influence the dielectric properties. The eye of round ( Semitendinosus ) muscle was selected because it contains large, relatively uniform muscle cells with similar muscle fiber orientation and relatively uniform chemical composition throughout the tissue. Dielectric properties were measured using an open-ended coaxial probe technique at 27, 915, and 1800 MHz and temperatures between −5 and 130 °C. Power penetration depth was calculated. Since many commercially prepared, thermally processed, ready-to-eat entrees are made with frozen meat, dielectric property measurements were started from −5 °C. The dielectric constant and dielectric loss factors were often higher for muscle with the muscle fiber measured in a parallel orientation to the probe compared to samples of the same treatment (for example, fresh or frozen) in a perpendicular tissue orientation at the same frequency and temperature. Dielectric constant and loss values for frozen beef tended to be higher than fresh beef at the same temperature and frequency. Tissue orientation appeared to have a greater effect on dielectric loss values at lower frequencies. Penetration depth tended to be greater when the direction of propagation was perpendicular to the muscle fiber.     

Effect of grape seed extract on oxidative, color and sensory stability of a pre-cooked, frozen, re-heated beef sausage model system

To compare grape seed extract (GSE) to common antioxidants in a pre-cooked, frozen, stored meat model system sausage was manufactured from lean beef (70%), pork fat (28%), and salt (2%). Antioxidants added for comparison with control included grapeseed extract (100, 300, and 500 ppm), ascorbic acid (AA, 100 ppm of fat) and propyl gallate (PG, 100 ppm of fat). Product was formed into rolls, frozen, sliced into patties, cooked on a flat griddle to 70 °C, overwrapped in PVC, then frozen at - 18 °C for 4 months. GSE- and PG-containing samples retained their fresh cooked beef odor and flavor longer (p < 0.05) than controls during storage. Rancid odor and flavor scores of GSE-containing samples were lower (p < 0.05) than those of controls after 4months of storage. The L* value of all samples increased (p<0.05) during storage. Thiobarbituric acid reactive substances (TBARS) of the control and AA-containing samples increased (p < 0.05); those of GSE-containing samples did not change significantly (p > 0.05) over the storage period.     

Optimization of the Freezing Conditions on Mackerel and Amberfish for Manufacturing Minced Fish

Optimal freezing, frozen storage and thawing conditions in preserving mackerel and amberfish for producing minced fish products were investigated. Based on assessments of extractability of 0.6M KCl-soluble proteins and actomyosin, Ca-ATPase activity of actomyosin, and gel-forming ability of kamaboko (kind of minced fish meat product), semi-dressed, dressed, and filleted samples showed stable and good quality of gel-forming ability during 3 months storage at −20°C. Optimal ultimate freezing temperatures of mackerel and amberfish were −20°C and between −30°C and −40°C, respectively. The optimal storage temperatures for mackerel and amberfish were −20°C and −40°C, respectively. Appropriate thawing methods for frozen mackerel were microwave and 20°C running water defrosting, while those for frozen amberfish were microwave, 20°C running water, and room temperature defrosting.     

Soy Protein and Oil Effects on Chemical, Physical and Microbial Stability of Lean Ground Beef Patties

Effects of isolated soy protein (ISP), frozen, textured isolated soy protein (FTISP), soybean oil (SO), and hydrogenated soybean oil (HSO) addition on chemical, color, sensory, and microbial stability of lean (>90%) ground beef patties (LGBP) were evaluated. Soy oil was incorporated as an emulsion (SE). Nine treatments, including two all beef controls (20 and 10% fat), were formulated to contain combinations of SE, HSO and FTISP. Sensory panelists found LGBP with 25% FTISP (10% fat from beef) to have as intense beef flavor (P>0.05) as all beef controls. Lipid oxidation and pigment discoloration rates were slowed by fat adjustment to 10% with SO and/or HSO. Soy had no effect (P>0.05) on microbial stability.     

EFFECTS OF SOY PROTEIN AND FREEZING TREATMENTS ON COOKING LOSS AND COMPOSITION OF BEEF PATTIES

All-beef and soy-extended patties were frozen to −18°C in either 24, 48, 72 or 96h and stored at −23, −18 or −7°C for 6, 9, 12, 18 or 24 months. The addition of soy resulted in a substantial reduction in cooking loss for patties cooked from the frozen state with a greater retention of moisture in cooked patties. Freezing reduced cooking loss for soy-extended patties, but increased cooking loss for all-beef patties. Faster freezing (-18°C in 24 h vs. −18°C in 96 h) reduced cooking loss and produced higher moisture values in all-beef patties. Patties stored at –7°C lost more moisture during cooking. Increased frozen storage time had a minimal effect on cooking losses, moisture and fat levels. Where it is essential for frozen patties to sustain minimal cooking losses with maximal moisture in cooked patties, the inclusion of soy protein concentrate, faster freezing, and storage at –18°C or colder are suggested.     

The effect of different levels of sunflower head pith addition on the properties of model system emulsions prepared from fresh and frozen beef

The effect of sunflower head pith on the functional properties of emulsions was studied by using a model system. Oil/water (O/W) model emulsion systems were prepared from fresh and frozen beef by the addition of the pith at five concentrations. Emulsion capacity (EC), stability (ES), viscosity (EV), colour and flow properties of the prepared model system emulsions were analyzed. The pith addition increased the EC and ES and the highest EC and ES values were reached when 5% of pith added; however, further increase in the pith concentration caused an inverse trend in these values. Fresh beef emulsions had higher EC and ES values than did frozen beef emulsions. One percent pith concentration was the critic level for the EV values of fresh beef emulsions. EV values of the emulsions reached a maximum level at 5% pith level, followed by a decrease at 7% pit level.     

Temperature Effect on Inactivation Kinetics of Escherichia coli O157:H7 by Electron Beam in Ground Beef, Chicken Breast Meat, and Trout Fillets

ABSTRACT:  Ground beef, boneless skinless chicken breast meat, and boneless skinless trout fillets were inoculated with Escherichia coli O157:H7 and incubated to approximately 10⁹ colony forming units per gram (CFU/g). Following incubation, temperature of the meat samples was equilibrated to −20, 4, and 22 °C. The meat samples at different temperatures were subjected to one-sided electron beam (e-beam) with fixed energy at 10 million electron volts (MeV) and doses at 0 (control), 0.5, 1.0, 2.0, 2.5, and 3.0 kGy. The survivors were enumerated using a standard spread-plating method. The survivor curves were plotted on logarithmic scale as a function of e-beam dose for each meat sample subjected to e-beam at different temperatures. The D -values were calculated as a negative reciprocal of the slope of the survivor curves. The D -values for E. coli ranged from 0.22 to 0.35 kGy in trout at 4 °C and chicken at −20 °C, respectively. The D -values were different between meat types. Regardless of temperature, E. coli in chicken had highest D -value followed by beef and trout. The D -values for E. coli in frozen samples were higher than D -values in samples irradiated at 4 and 22 °C regardless of species. Although there were numerical differences between D -values for samples subjected to e-beam while chilled (4 °C) or frozen (−20 °C), they were statistically insignificant. Water radiolysis is considered as an indirect mechanism for microbial inactivation. Therefore, while the physical state of water (frozen or unfrozen) in foods seems the major contributor to microbial inactivation by e-beam due to water radiolysis, product temperature most likely plays a minor role.     

Effect of natural antioxidants on oxidative stability of cooked, refrigerated beef and pork

ABSTRACT:  The effect of grape seed extract (GS; 0.01% and 0.02%), oleoresin rosemary (OR; 0.02%) and water-soluble oregano extract (WS; 0.02%) on oxidative and color stability of cooked beef and pork patties stored at 4 °C for 8 d was determined. Fresh beef or pork lean and trim were ground, mixed (30% fat), and divided into 5 portions. Antioxidants mixed with salt (2%) were added. Patties were formed, cooked to an internal temperature of 71 °C, overwrapped in PVC, and stored at 4 °C. Lipid oxidation, assessed using thiobarbituric acid reactive substances (TBARS) and sensory evaluation, instrumental and visual color, and pH were determined after 0, 2, 4, 6, and 8 d. Based on TBARS values and off-odors associated with lipid oxidation such as rancidity, wet cardboard (for beef patties), and grassy (for beef and pork patties), grape seed extract resulted in the best antioxidant activity in both meat species. It did not change instrumental color measures of redness, yellowness, or color intensity, and appeared to reduce visual green discoloration in beef patties. The higher GS concentration (0.02%) exhibited more antioxidant activity than the lower concentration (0.01%). Therefore, grape seed extract at 0.02% has the potential to reduce oxidative rancidity and improve shelf life of refrigerated cooked beef and pork patties.     

Thermal Inactivation of Salmonella spp., Salmonella typhimurium DT104, and Escherichia coli 0157:H7 in Ground Beef

ABSTRACT: In 19.1% fat ground beef, Escherichia coli 0157:H7 was less heat- resistant at ≥58°C than the Salmonella typhimurium DT104 and Salmonella senftenberg , but at 55°C the D value was similar to DT104 strains and higher than an eight-strain Salmonella cocktail. Inactivation of E. coli 0157:H7 was more temperature-dependent than the cocktail and DT104 strains. E. coli and DT104 strains were more heat-resistant in beef containing 19% fat than 4.8% fat. The cocktail was more thermally stable in stationary as compared to log phase. Freezing of inoculated raw meat decreased heat resistance of the cocktail. The pathogenic strain, growth phase of the organism, state of the meat (fresh or frozen) and meat composition must be considered when designing protocols to verify thermal processes.     

Effects of different types of carrageenans and carboxymethyl celluloses on the stability of frozen stored minced fillets of cod

Different types of carrageenans and carboxymethyl celluloses were used as additives (5 g/kg) for minced fillets of cod. Samples of these treatments were stored at −18°C for 10 weeks and were evaluated at regular intervals for pH, water holding capacity, texture, extractable myosin and formation of dimethylamine and formaldehyde.
Except Kappa carrageenan the additions improved the water holding capacity of the raw and cooked minced fish and decreased toughening during frozen storage. The addition of Iota carrageenan resulted in samples with remarkable texture stability and so after 10 weeks of frozen storage the texture of this treatment was similar to fresh minced cod. The higher the viscosity of carboxymethyl cellulose, the more it increased the softness and water holding capacity.     

External Fat Cover Influence on Raw and Cooked Beef. 1. Fat and Moisture Content

SUMMARY: The fat content of beef semitendinosus muscle, raw and cooked at two oven temperatures, with and without the external fat cover, has been determined. Each muscle was divided into two, an anterior and a posterior roast. The external fat cover was removed from half of the total number of roasts, and all roasts were then cooked to an internal temperature of 58°C at an oven temperature of either 163° or 218°C. Two types of samples were analyzed for their moisture and fat content. These were a separable lean sample and a total sample. The total sample was composed of both the separable lean and the external fat cover. The moisture content of the lean samples was not affected by the oven temperature, the external fat cover or the end of the muscle used. The total samples had moisture contents that reflected the amount of crude fat present. The yield of crude fat from raw or cooked meat was not significantly altered by the use of a polar solvent in place of a nonpolar one. Both of the fat determination methods extracted significantly more fat from the cooked lean samples than from the comparable raw ones. The lean samples from meat roasted at 163°C contained significantly more extractable fat than the samples roasted at 218°C. The presence or absence of the external fat cover did not affect the amount of fat extracted from the cooked lean.     

W/O型人造肥牛脂肪的品质改进研究

人造肥牛脂肪是一种白色或乳白色黏稠状W/O型食品乳状液。在前期研究的基础上,通过在油相中添加牛油,应用油脂的同质多晶型特点及牛油的特殊组成来提高肥牛脂肪的稳定性;用一级大豆油与三级大豆油适当调配,来改善肥牛脂肪的颜色。实验结果表明,添加牛油的肥牛脂肪与未加牛油的相比乳化稳定性大大提高,可达到99.5%,而且脂肪的结构、质地、风味也得到改善;三级大豆油添加量为10%时,肥牛脂肪的黄度与亮度与天然牛油最接近。