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This study investigated the physicochemical properties of sausages made from meat alternatives made from Maillard‐reacted beef bone hydrolysate and plant proteins (soy protein and wheat gluten) at different moisture contents (MC; S49%MC, S52%MC, S56%MC and S60%MC). S49%MC had the highest hardness and chewiness, observed with chunks of long fibres under SEM. The hardness and chewiness of sausages decreased as MC increased. S60%MC exhibited soft and mushy texture, and no fibre structure was observed. Sausages made from meat alternatives had higher protein oxidation as compared with reference sausage made from chicken breast (SCB), which could be due to longer storage period, as meat alternatives were extruded, frozen and stored before making into sausages. Sensory results showed that SCB obtained the highest scores for all attributes except for appearance, among all sausages. Overall results showed that further improvements can be made when using extruded meat alternatives to make sausages.

Summary Freezing and thawing technologies are widely used in meat industry. This study aimed to investigate the effects of freezing and different thawing methods (Control group, CG; water immersing thawing, WT; low temperature combined with high-humidity thawing, LT; combined thawing 1 (WT 15 min, then LT), CT1; combined thawing 2 (LT 2 h, then WT), CT2) on the quality of chicken breast. The results showed that all thawing methods significantly increased shear force value, the gap between muscle fibres, the contents of malondialdehyde (MDA) and carbonyl compounds, meanwhile, decreased the pH, CIE a* value, total protein solubility and sarcoplasmic protein solubility, compared with CG (P

Summary Influences of sodium tripolyphosphate (STPP) contents (0.1, 0.2, 0.3 and 0.4%) on water holding capacity (WHC) and texture properties of low-salt (1.2% NaCl) single-step high-pressure processed chicken breast sausages (LSSS-HPP sausages) were evaluated. Results showed that WHC was improved (4–5%) by the addition of STPP. However, the STPP contents customarily used for cooked sausages (0.3–0.5%) were excessive for LSSS-HPP sausages, causing a soft and tacky texture. Sausages containing 0.1% of STPP had the best taste according to the sensory evaluations. Chemical interactions plus Raman spectroscopic analysis revealed that STPP addition partly changed native structures of myofibrillar proteins. Furthermore, higher STPP contents in the meat batter prevented those proteins from high pressure denaturing and aggregating in the subsequent single-step HPP procedure. Increased hydrogen bonds and decreased hydrophobic interactions explained the better WHC and softer texture. Therefore, 0.1% of STPP is the optimal content in the processing of new-type LSSS-HPP sausages.

Summary The effects of 5 mm l-histidine (l-His) on water-binding capacity, gel strength, thermal gelling properties of chicken breast myofibrillar proteins (MPs) in 1 mm NaCl or 0.6 m NaCl solutions (pH 7.0) were investigated. l-His could significantly increase the solubility and thermal gelling ability of MPs in 1 mm NaCl. l-His at 1 mm NaCl shortened the water relaxation time and decreased the water mobility of MPs gel. l-His promoted the formation of MPs gel structure with small pores and thin strands at 1 mm NaCl. These resulted in the enhanced water retention and weak gel strength of MPs in low ionic strength solution. The water-binding capacity of MPs gels formed in 1 mm NaCl containing 5 mm l-His was equivalent to that with 0.6 m NaCl. The information could offer certain theoretical foundation to apply l-His as sodium salt substitute for developing low-salt meat gelling product with high yield.

Summary During thermal food preparation, it is essential for the product to reach safe temperature thresholds. Yet, excessive cooking is time-consuming and decreases desirable qualities. In this work, we developed, and experimentally verified, a computationally minimum mathematical model to predict one-dimensional temperature distribution through contact cooking of poultry. This model was based on discretising the heat equation with temperature and time varying thermophysical properties of the major constituents: water, proteins and lipids. The relative amounts of these constituents are available from the United States Department of Agriculture (USDA) for different poultry samples. Our results yielded an average modelling experimental temperature error of 3.15 °C. For contact cooking of a 1-cm thick sample, the minimum time to reach the temperature threshold in a chicken breast was 368 s compared to 98.9 s when flipped at an optimised time. These techniques can be implemented into a microprocessor-based thermal monitoring system to non-invasively predict temperature distribution in processed meat and poultry.

Summary Immersion in hot water is one of many potential methods for reducing levels of pathogenic bacteria on the surface of poultry meat. However, if the meat is to be sold in the raw state reductions in microbiological numbers need to be achieved without changing the appearance of the meat. Samples of vacuum-packed skin-on chicken breast were immersed in hot water for a range of temperatures and times. Samples were then water cooled to arrest further heating. The final appearance of the samples was assessed visually and instrumentally with a chroma meter. Surface and internal temperatures were also measured. From this series of initial experiments a range of maximum temperature–time treatments were identified that would not cause unacceptable changes to surface appearance. Microbiological tests were then conducted on samples inoculated with a nalidixic acid resistant strain of Escherichia coli serotype O80 subjected to these treatments. The results showed that determining changes to the appearance of skin from samples by using a chroma meter was difficult. The changes caused to the samples by heat treatment were initially textural rather than colourimetric and thus could be identified visually but not instrumentally with a chroma meter. Visual changes were found for immersion times greater than 120 s at 50 °C, 60 s at 60 °C, 9 s at 70 °C, 6 s at 80 °C, 2 s at 90 °C and 1 s at 100 °C. The average temperatures measured on the surface after 2 s immersion at 90 °C and after 60 s at 60 °C were 20.5 °C and 54.8 °C, respectively. No reductions in counts of E. coli serotype O80 were measured on samples treated under these conditions. The results indicate that there is no immersion heat treatment (below 90 °C) capable of reducing contamination with E. coli, or similar thermotolerant microorganisms, on poultry without causing adverse changes in the product.

Water activity (a w ) of ground beef, chicken breast meat, and trout fillets was modified to intermediate (a w 0.98-0.99) and lowest (a w 0.94-0.96) levels. The meat samples with modified and unaltered (native, a w 1.00) a w were inoculated with Escherichia coli O157:H7 and subjected to electron beam (e-beam). Survivor curves were plotted and the D 10 -values were calculated. The D 10 -values ranged from 0.22 kGy for trout at native a w to 0.33 kGy for beef at intermediate, and chicken and trout at lowest a w . Regardless of the species, a w reduction increased E. coli resistance to e-beam, suggesting that even small depletion of unbound water from food increases survival. The difference of the D 10 -values between the samples at intermediate and lowest a w was insignificant. E-beam could be used before a w -reducing techniques are applied to food products. However, this would require stringent microbial control following e-beam processing. The 'tailing' of survivors was observed for some samples with reduced a w .

Summary The colour of irradiated and unirradiated chicken breasts was measured at two laboratories (A & B). The effect of instrumental differences on the CIELAB colour co-ordinates and reflex attenuance spectra of the chicken breasts was examined. Each laboratory used two spectrophotometers, one of which was common to both. Laboratory B operated their other spectrophotometer in two different measuring geometries. Irradiated chicken breasts were found to exhibit increased a* values (greater redness) when compared with the unirradiated controls. Although differences in absolute CIELAB co-ordinates were found between instruments, all the instruments evaluated indicated increased redness and chroma values for the irradiated samples. Examination of reflex attenuance spectra indicated that the increases in a* observed were due to lesser absorption of light in the 600–700 nm region, although evidence of a change in pigment form was limited.

Summary A method for rapid detection of the presence of injected polyphosphate or a mixture of polyphosphate and sodium chloride solutions in broiler breast muscle has been developed. Detection is based on the ratio of sodium and phosphorus (as P2O5) concentrations found in a trichloroacetic acid (TCA) extract of the muscle. Comparison of acid digested and undigested TCA extracts showed that the presence of these added salts could be demonstrated equally well without acid digestion. The method has been satisfactorily applied to the analysis of deep-frozen broilers purchased from supermarkets.

Summary Chicken breast and salmon muscle were frozen either slowly or rapidly at –25°C, and then stored at –5°C for up to 83 and 47 days respectively. At intervals samples were thawed and TBA values measured on either muscle distillate or centrifugal exudates. TBA values increased slightly but significantly with storage time, but freezing rate had no effect.

Summary The use of dry whole milk, skimmed milk, caseinate, regular and modified whey, at 2% level (w/w) and with 2% additional protein level was studied in a chicken breast meat system with 51% water addition. At the 2% (w/w) level, all dairy proteins significantly reduced cooking loss compared with the control, with caseinate showing the best results. When compared on an equal protein level (2% total protein), the best performing ingredients were the whole milk and modified whey. A similar observation was made in their effect on the products’ hardness and fracturability. A cost analysis revealed that modified whey provided the most economical ingredient even when used in quantities three times greater than that of as caseinate. Microscopy results showed the formation of larger fine-protein-matrix regions in the treatments that provided higher fracturability values.