Dynamic rheology and endothermic transitions of proteins recovered from chicken-meat processing by-products using isoelectric solubilization/precipitation and addition of TiO2

Chicken-meat processing generates large quantities of by-products (backs, necks, etc.). Dark chicken-meat processing by-products present the lowest value and greatest challenge. Therefore, recovery of functional proteins from this source for inclusion in food products resembling those from light chicken-meat presents the greatest value addition and opportunity. Novel isoelectric solubilization/precipitation (ISP) was applied to model, dark chicken-meat processing by-products (skin-on bone-in chicken drumsticks) to recover muscle proteins. Thermal denaturation (endothermic transitions), gelation (elasticity, G′), and fundamental texture properties (shear stress and strain at mechanical fracture) of the ISP-recovered proteins were determined with differential scanning calorimetry (DSC), dynamic rheometer, and torsion test, respectively; and compared to boneless skinless chicken breast. Endothermic transition of myosin was not detected only when TiO₂ was not added, while the ISP-recovered proteins with TiO₂ showed small myosin peak and large actin peak. However, the level of TiO₂ addition did not affect thermal transition/denaturation of the ISP-recovered proteins. The ISP-recovered proteins had a greater transition for actin compared to chicken breast, suggesting that ISP predisposes this protein to thermal denaturation. Similar to endothermic transitions, elasticity (G′) generally increased when TiO₂ was added to the ISP-recovered proteins. Gels made of chicken breast had the highest (P < 0.05) shear stress (i.e., gel strength), but gels made of the ISP-recovered chicken proteins had greater (P < 0.05) shear strain (i.e., gel cohesiveness). Addition of TiO₂ to the ISP-recovered proteins resulted in increased (P < 0.05) gel strength. Based on the present study, addition of TiO₂ is suggested for the development of restructured food products based on proteins recovered from dark chicken-meat processing by-products using ISP. Although the results of this study point towards a novel food product, further studies are recommended.     

Color improvement by titanium dioxide and its effect on gelation and texture of proteins recovered from whole fish using isoelectric solubilization/precipitation

Whiteness is a critical attribute for restructured fish products such as surimi seafood. However, the whiteness of gels made from proteins recovered from fish processing by-products or whole fish using isoelectric solubilization/precipitation is poor. The by-products and whole fish contain bones, scales, skin, etc. that affect gel color. Therefore, whiteness needs to be improved if marketable products are to be developed from recovered proteins. The objectives of this study were to determine effects of titanium dioxide (TiO₂) on: (1) color; (2) texture; and (3) viscoelasticity (G′) of gels made from isolated carp proteins and Alaska pollock surimi. Carp proteins were recovered with isoelectric solubilization/precipitation. TiO₂ was added to carp proteins at 0-0.5 g/100 g. TiO₂ was not added to surimi. Due to much higher (P < 0.05) yellowness (b^∗) and lower (P < 0.05) lightness (L^∗), the whiteness of carp gels without TiO₂ was lower (P < 0.05) than surimi gels. TiO₂ at ≥ 0.2 g/100 g resulted in better (P < 0.05) whiteness of carp gels than surimi gels without chalky and artificially white appearance. TiO₂ did not affect texture or viscoelasticity. This research demonstrates that whiteness of restructured fish products based on proteins recovered from whole fish via isoelectric solubilization/precipitation can be similar to the whiteness of surimi seafood.     

A three-prong strategy to develop functional food using protein isolates recovered from chicken processing by-products with isoelectric solubilization/precipitation

BACKGROUND: Skin‐on bone‐in chicken drumsticks were processed with isoelectric solubilization/precipitation to recover muscle proteins. The drumsticks were used as a model for dark chicken meat processing by‐products. The main objective of this study was conversion of dark chicken meat processing by‐products to restructured functional food product. An attempt was made to develop functional food product that would resemble respective product made from boneless skinless chicken breast meat. A three‐prong strategy to address diet‐driven cardiovascular disease (CVD)with a functional food was used in this study. The strategy included addition of three ingredients with well‐documented cardiovascular benefits: (i) ω‐3 polyunsaturated fatty acid‐rich oil (flaxseed‐algae, 9:1); (ii) soluble fiber; and (iii) salt substitute. Titanium dioxide, potato starch, polyphosphate, and transglutaminase were also added. The batters were formulated and cooked resulting in heat‐set gels. RESULTS: Color (L*a*b*), texture (torsion test, Kramer shear test, and texture profile analysis), thermal denaturation (differential scanning calorimetry), and gelation (dynamic rheology) of chicken drumstick gels and chicken breast gels were determined and compared. Chicken drumstick gels generally had comparable color and texture properties to the gels made from chicken breast meat. The endothermic transition (thermal denaturation) of myosin was more pronounced and gelation properties were better for the drumstick gels. CONCLUSION: This study demonstrated a feasibility to develop functional food made of muscle proteins recovered with isoelectric solubilization/precipitation from low‐value dark chicken meat processing by‐products. The functional food developed in this study was enriched with CVD‐beneficial nutrients and had comparable instrumental quality attributes to respective products made of chicken breast meat. Although the results of this study point towards the potential for a novel, marketable functional food product, sensory tests and storage stability study are recommended. Copyright © 2012 Society of Chemical Industry     

Functional properties of proteins recovered from silver carp (Hypophthalmichthys molitrix) by isoelectric solubilization/precipitation

Isoelectric solubilization/precipitation at acidic and basic pH ranges was applied to whole gutted silver carp (Hypophthalmichthys molitrix) in order to recover muscle proteins. Thermal denaturation (T_onset, T_max, and ΔH), viscoelasticity (G′), and texture properties (shear stress) of proteins recovered from carp as affected by functional additives (beef plasma protein, potato starch, exogenous transglutaminase, polyphosphate, and titanium dioxide) were determined and compared to Alaska pollock surimi. Proteins recovered from carp showed typical endothermic transitions only when functional additives were used. Similar to endothermic transitions, viscoelasticity in carp proteins increased only when the additives were used. Typical endothermic peaks and viscoelasticity increase were recorded for Alaska pollock surimi. Carp protein-based gels with functional additives had lower (P < 0.05) shear stress than their surimi counterparts, but greater (P < 0.05) or similar (P > 0.05) when compared to surimi gels without functional additives. In addition, generally higher shear stress was measured for carp protein-based gels developed from basic pH treatments than the acidic counterparts. The present study indicates that proteins can be recovered from whole gutted carp using isoelectric solubilization/precipitation. However, if the recovered proteins are used for subsequent development of restructured food products, functional additives should be used.     

Flocculation-enhanced protein recovery from fish processing by-products by isoelectric solubilization/precipitation

Muscle proteins were recovered from rainbow trout processing by-products (fish meat leftover on bones, head, skin, and etc.) by isoelectric solubilization/precipitation. Muscle proteins precipitated at pH 5.5 are typically recovered by high-speed centrifugation at a laboratory scale, which appears to impede process scale-up. Our objective was to investigate the effect of flocculants on separation of precipitated proteins from process water (supernatant). Flocculants with different surface charge properties and molecular weights (M_w) were added to precipitated proteins. Protein separation was evaluated by determining optical density (OD) of the supernatant using Bradford dye-binding method. A high M_w anionic flocculent at 100 mg/L resulted in excellent protein separation following 10 min reaction. The OD of the supernatant was comparable to that of clear water, suggesting that even water-soluble fish muscle proteins were removed from the process water. Freeze-thaw cycles, commonly encountered in the fish processing industry, resulted in even more rapid flocculation reaction. This flocculent could be added to a bio-reactor that precipitates muscle proteins at pH 5.5 in a continuous isoelectric solubilization/precipitation system. However, effects of the flocculants on human and animal health should be determined and appropriate approvals obtained before the recovered muscle proteins can be used in human food products and/or animal feeds.     

High pressure effect on the color of minced cured restructured ham at different levels of drying, pH, and NaCl

Color changes of minced cured restructured ham was studied considering the effects of high pressure (HP) treatment (600 MPa, 13 °C, 5 min), raw meat pH₂₄ (low, normal, high), salt content (15, 30 g/kg), and drying (20%, 50% weight loss). Raw hams were selected based on pH₂₄ in Semimembranosus, mixed with additives, frozen, sliced, and dried using the Quick-Dry-Slice® process. Meat color (CIE 1976 L*a*b*) and reflectance spectra were measured before and after HP treatment. HP significantly increased L*, decreased a*, and decreased b* for restructured ham dried to 20% weight loss, regardless of salt content and pH₂₄. L* and a* were best preserved in high pH/high salt restructured ham. HP had no effect on the color of restructured ham dried to 50% weight loss. HP had no effect on the shape of reflectance curves, indicating that the pigment responsible for minced cured restructured ham color did not change due to HP.     

Optimization of in-package cold plasma treatment conditions for raw chicken breast meat with response surface methodology

Response surface methodology (RSM) was used to optimize in-package cold plasma (IPCP) treatment for raw chicken breast meat. Non-inoculated and inoculated samples with Campylobacter (5.06 log₁₀ CFU/mL) and Salmonella (5.40 log₁₀ CFU/mL) were packaged in 35% O₂/60% CO₂, 65% O₂/30% CO₂, or 95% O₂/0% CO₂ and treated at 60, 70, or 80 kV for 60, 180, or 300 s. Microbial counts, color, pH, and drip loss were measured. There were no differences in Campylobacter, Salmonella, drip loss, or pH between treatments. IPCP could reduce psychrophiles by >1.0 log, depending on O₂ and voltage interaction. Treatment effects on meat color varied by CIE L*a*b*. RSM analysis suggested that packaging atmosphere with 35% O₂ and 60% CO₂ and IPCP at 60 kV for 60 s were the optimal condition for maximizing microbiological shelf-life and minimizing appearance changes in raw chicken meat packaged in a barrier film and stored at 4 °C for 5 days.Industrial relevanceThe current study used response surface methodology to determine the optimal condition in the combination of voltage and time of an in-package cold plasma (IPCP) treatment and modified atmosphere (MA) packaging for extending shelf life and reducing food safety risk of pre-packaged raw chicken breast meat during refrigerated storage. Our data provided evidence that the optimal IPCP-treatment parameters and packaging atmosphere varied with targeted microorganisms and CIEL*a*b* color indicators. In MA packaging, changes in IPCP treatment voltage and time did not affect populations of Campylobacter and Salmonella, drip loss and pH; however, low IPCP treatment voltage (60 kV) for short exposure time (60 s) was as effective as the high voltage (80 kV) for longer treatment time (300 s) against psychrophiles and could reduce the changes in raw meat appearance (indicated with CIEL* measurements) due to IPCP treatment. Reducing O₂ in packages from 95 to 35% resulted in better inhibition of psychrophilic growth on raw meat and changes in raw meat appearance or meat color lightness. It is recommended to use MA of 35% O₂ and 60% CO₂ and IPCP treatment at 60 kV for 60 s to extend microbiological shelf life, improve food safety, and retain quality of raw chicken breast meat packaged with a barrier film and stored at refrigerated temperature.     

Mechanical and functional properties of beef products obtained using microbial transglutaminase with treatments of pre-heating followed by cold binding

Beef proteins are considered non-setting proteins and usually gels obtained by adding of microbial transglutaminase are obtained by cooking directly the solubilized paste. The aim of this work was to determine the effect of pre-heating treatments on the mechanical properties of restructured beef gels treated with microbial transglutaminase (MTG). The effect of cooling (cold binding) the solubilized pastes after the pre-heating treatments was also studied. The restructured beef gels were obtained by adding 0.3% MTG or 0% MTG (control). Three pre-heating temperatures (40, 50 or 60 °C) for 30 or 60 min were studied, followed by heating at 90 °C for 15 min. Control samples without pre-heating were also prepared. Cold binding was studied by holding pre-heated gels at 4 °C for 12 h before heating at 90 °C for 15 min. Changes in mechanical properties (texture profile analysis and puncture test), color attributes, expressible water and cooking loss were determined. Results indicated that the better mechanical properties can be obtained by pre-heating beef pastes at 50 °C for 30 min with minimal effect on color, expressible water and cooking loss when 0.3% of MTG is added. It was concluded that there were no practical advantages by pre-heating the gels for 60 min. Cold binding did not improve the mechanical properties of beef gels.     

Butternut and beetroot pectins: Characterization and functional properties

The physicochemical characteristics and functional properties of butternut (Cucumis moschata Duch. ex Poiret) and beetroot (Beta vulgaris L. var. conditiva) pectins obtained by enzymatic extraction from by-products of vegetable processing have been evaluated. The molecular mass distribution was determined using Gel Permeation Chromatography using light scattering, refractive index and UV detectors and the samples were found to be highly heterogeneous and polydisperse. M_w values of 136,000 and 1,309,000 g/mol were determined for butternut and beetroot pectins respectively. Butternut pectin had a high degree of methyl esterification. In the presence of high concentrations of sugar and at low pH, this pectin did not form gels but instead produced viscous solutions. Solutions showed pseudoplastic flow behaviour with a shear thinning index of 0.68 as determined from the Power law model. Beetroot pectin had a low degree of methyl esterification and formed gels with addition of Ca²⁺ at concentrations of 10 mg/g pectin or higher. The maximum value of the storage modulus was obtained at a Ca²⁺/GalA ratio of 0.25. The thermal stability of gels suggested that hydrogen bond interactions prevailed in the absence of Ca²⁺, whereas electrostatic junction zones increasingly developed between pectin chains as the calcium concentration increased. Aqueous solutions of butternut and beetroot pectins significantly reduced surface tension and both samples were able to form stable oil-in-water emulsions. It was found that protein and/or polyphenol – rich fractions present in the pectins adsorbed at the oil–water interface and were responsible for the emulsification properties.     

Kinetic Modeling of Texture and Color Changes During Thermal Treatment of Chicken Breast Meat

Heat treatment is commonly applied as a primary method for ensuring the microbial safety of poultry meat and to enhance its palatability. Although texture and color of cooked chicken breast meat are important quality parameters for the consumers that need to be controlled during thermal processing, studies assessing the temperature-time-dependent quality changes during thermal treatment are lacking. This work aims to investigate the texture and color changes of chicken breast meat during thermal processing and to develop kinetic models that describe these changes. We studied the storage modulus changes of chicken breast meat as function of temperature. The storage modulus increases from 55 °C until leveling off in an equilibrium value above 80 °C, which was attributed to microstructure changes and described with a sigmoidal function. The changes in the texture (TPA) and color (CIE L ^* a ^* b ^* ) of chicken breast meat were measured as function of temperature and time. The texture and color parameters show a rise with heating time until reaching an equilibrium value, while the rate of change increased with temperature. Kinetic models that take the non-zero equilibrium into account were developed to describe the color (lightness) and texture (hardness, gumminess, and chewiness) changes with heating time and temperature. The kinetic models provide a deeper insight into the mechanisms of texture and color changes during thermal treatment. They can be used to predict the texture and color development of chicken breast meat during thermal processing and, thus, help to optimize the process.     

Inhibitory effects of lactic acid and lauricidin on spoilage organisms of chicken breast during storage at chilled temperature

Different concentrations of lauricidin (LU, containing 1% lactic acid) and lactic acid alone (LA) were evaluated for their effectiveness in reducing naturally occurring microflora of raw chicken breasts. Chicken breasts were dipped in 0 (control), 0.5, 1.0, 1.5, and 2.0% solutions of LU (w/v) or LA (v/v) for 10, 20, and 30 min and stored at 4 °C for 14 d. Total Plate Counts (TPC) and populations of Pseudomonas spp. and Enterobacteriaceae were determined before and after dipping and after storing for 1, 3, 7, 10, and 14 d. Additionally, Hunter L, a, and b values and pH of the chicken breast were also determined. From the obtained results, TPC on chicken breast treated with LU was found to be decreased by 0.92 to 1.2 log CFU/g from a mean initial log 5.69 CFU/g, while those dipped in LA decreased by 0.53 to 2.36 log CFU/g. Pseudomonas population on chicken breast dipped in LU decreased by 0.79 to 1.77 log CFU/g from an initial 3.90 log CFU/g, while in LA treated it decreased by 0.39 to 1.82 log CFU/g. Enterobacteriaceae counts were also found to be reduced by 0.14 to 1.14 log CFU/g on chicken breast dipped in LU, while the reduction was from 0.59 to 2.18 log CFU/g in chicken breast dipped in LA. The major bacterial types isolated from LU treated chicken breast belonged to the Enterobacteriaceae group, which included: Enterobacter, E. coli and Citrobacter. Whereas, in the LA treated breast it belonged to: Pseudomonas, E. coli, and Kocuria rhizophila (formerly Micrococcus luteus). Dipping chicken breast in LU and LA caused a significant decrease (p ≤ 0.05) in their pH values. Also, treatment with LU and LA caused a slight darkening in color (decreased Hunter L value), increase in redness (increased Hunter a value), and increase in yellowness (increased Hunter b value). Based on the results obtained in the present study, Lactic acid and Lauricidin showed high potential to be used as a sanitizer in reducing the population of spoilage microorganisms naturally occurring on raw chicken, and can be explored commercially for extension of their shelf life.     

A combination of TiO2–UV photocatalysis and high hydrostatic pressure to inactivate Bacillus cereus in freshly squeezed Angelica keiskei juice

High hydrostatic pressure (HHP) is an effective nonthermal food processing method for microbial inactivation with minimal change to sensory and nutritional values. However, the resistance of endospores to high pressure hinders application of HHP to freshly squeezed vegetable juice, especially from leafy vegetables that are susceptible to contamination of soil bacteria, such as endospore-forming Bacillus cereus. A combination of TiO₂–UV photocatalysis and HHP was used in the processing of freshly squeezed Angelica keiskei juice, and inactivation of naturally occurring microbes, especially B. cereus, was investigated. Yeasts and molds, coliform bacteria, and Pseudomonas were inactivated by HHP to levels below the detection limit, but B. cereus survived HHP and grew during 8 days of subsequent refrigerated storage (4 °C). However, no colonies of yeasts and molds, coliform bacteria, Pseudomonas, or B. cereus were detected in A. keiskei juice after processing with a combination of TiO₂–UV photocatalysis and HHP. Although B. cereus in juice processed with the combination treatment recovered and grew to 2.02 log CFU/mL on day 6 of storage, this level was less than the population of B. cereus in unprocessed Angelica keiskei juice immediately after squeezing.     

Rosemary as antioxidant in pressure processed chicken during subsequent cooking as evaluated by electron spin resonance spectroscopy

The potential of rosemary (Rosmarinus officinalis L.) to inhibiting lipid oxidation in minced chicken breast and thigh muscle processed at 600 MPa for 10 min during subsequent heat treatment was investigated using electron spin resonance (ESR) spectroscopy and electrochemical detection of oxygen consumption. Chicken breast cooked at 95 °C was found to have significantly higher rate of formation of free radicals and oxygen consumption rate than the samples cooked at 70 °C and 120 °C and this intermediate cooking temperature was used to evaluate the effect of pressure on oxidation during subsequent cooking. Rosemary was found effective in retarding lipid oxidation since the pressurized, minced chicken breast and thigh with rosemary added showed lower rate of oxygen consumption and lower tendency of free radical formation following heat treatment than the samples without rosemary. Pressurized chicken thigh showed a higher susceptibility to oxidation than chicken breast upon subsequent heat treatment. Oxidation in pressurized and subsequently heat-treated chicken breast was from a higher tendency of radical formation concluded to be in an earlier phase of oxidation compared to thigh subjected to the same treatment.Industrial relevanceHigh-pressure processing has a great potential for microbial control of raw chicken meat as a “fresh” chill-stored, convenience product for wok cooking. While raw chicken meat is oxidatively stable, high-pressure treatment at 600 MPa and above induces lipid oxidation resulting in off-flavors during subsequent cooking. Addition of 0.1% dried rosemary to minced chicken thighs or breasts prior to high-pressure processing inhibit lipid oxidation during subsequent cooking and could form the basis for product development.     

Preparation and characterisation of chicken skin gelatin as an alternative to mammalian gelatin

The aims of this study were to report for the first time, the extraction and physico-chemical properties of chicken skin gelatin compared to bovine gelatin. Extracted chicken skin gelatin 6.67% (w/v) had a higher bloom value (355 ± 1.48 g) than bovine gelatin (259 ± 0.71 g). The dynamic viscoelastic profile of chicken gelatin exhibited higher viscous and elastic modulus values compared to bovine gelatin for a range of concentrations and frequencies. Thermal properties studied by differential scanning calorimetry (DSC) showed that the melting temperature of 6.67%, chicken skin gelatin was significantly greater (p < 0.05) than that of bovine gelatin, indicating lower stability of bovine gelatin compared to chicken skin gelatin. Results obtained in this study showed that Gly (33.70%), Pro (13.42%), H.Pro (12.13%) and Ala (10.08%) were the most dominant amino acids in chicken skin gelatin which contributed to the higher gel strength and stability. Raman spectra of chicken skin and bovine gelatin were similar and displayed typical protein spectra. Chicken gelatin showed strong hydrogen bonding compared to bovine gelatin as the tyrosine doublet ratio (I₈₅₅/I₈₃₀) of chicken gelatin was significantly lower than that of bovine gelatin. Significantly, the alpha helix and β-sheet type structures were higher for chicken skin gelatin compared with bovine gelatin. The average molecular weight of chicken gelatin was 285,000 Da. These findings, obtained for the first time for chicken skin gelatin, show that it has high potential for application as an alternative to commercial gelatin.     

Gelling properties of protein fractions and protein isolate extracted from Australian canola meal

Gelling properties of canola albumin and globulin fractions, and canola protein isolate (CPI) were examined in this study. The effects of pH and salt concentration on canola protein gelling properties were studied primarily by means of dynamic oscillatory rheology and gel texture analysis. The findings were supported by confocal laser scanning microscopy (CLSM) images of the gels, isoelectric point, and solubility measurement data. All canola proteins showed typical heat-set gel protein profiles. Gels formed at higher pH had better gelling properties including higher overall resistance to deformation (G*), higher gel elasticity (low tan δ ), higher fracture stress and firmness, and denser gel microstructure. Isoelectric points of canola proteins used in this study were in the range of pH 3.0–4.7 where low protein solubility was observed. The albumin fraction was able to form a very weak gel at pH 4, whereas the globulin fraction and CPI precipitated due to loss of protein surface charge. The effects of NaCl on gelling were protein sample dependent. The presence of NaCl negatively affected gelling properties of albumin and globulin fractions, with decreases in overall resistance to deformation (G*), and fracture stress and firmness, but positively affected CPI gels in the same aspects. The elasticity (tan δ) of all canola protein gels remained constant in the presence of NaCl. Frequency sweep analysis revealed that the albumin fraction and CPI formed weak gels, whereas the globulin fraction formed a strong gel. Strain sweep analysis further confirmed that the globulin fraction formed a stronger gel with a critical strain of at least 10%. This study demonstrates the high potential of canola proteins, particularly the globulin fraction, as a prospective gelling agent.     

Effects of vegetable oils on gel properties of surimi gels

The objective of this study was to determine effects of vegetable oils (soybean, peanut, corn, and rap oils) on the textural, color, microstructural, sensory and rheological properties of surimi gels. As the vegetable oil concentration increased in surimi gels, breaking force of gels was decreased (P < 0.05), while expressible water and whiteness values were increased (P < 0.05). Surimi gels with peanut oil had higher breaking force values, comparing to those with other vegetable oils. Transmission electron microscope shows the similar-size droplets of peanut oil and corn oil in surimi gels. Sensory evaluation indicated that fish balls with 10 g/kg vegetable oils were accepted in term of taste, color and overall likeness by the panelists. Storage modulus (G′) and loss modulus (G″) decreased along with increasing vegetable oil concentration. Results demonstrated that vegetable oils could be used potentially to modify the qualities of surimi-based products, such as color and taste.     

To improve the gel properties of liquid whole egg by short-term lactic acid bacteria fermentation

Fermentation, as a simple, safe and environmentally friendly technology, is promising in the modification of proteins. In this study, the liquid whole egg (LWE) was fermented at 37 °C by Lactiplantibacillus plantarum 90 (L. plantarum 90) which the dose of inoculation was about 8 Log 10 CFU mL⁻¹. During the process, the total aerobic mesophilic count (TAM) and the number of lactic acid bacteria (LAB) of LWE increased at 3 h and then decreased, consistent with the changes in protein solubility. Besides, the T₂ relaxation time of fermented egg gels moved to low relaxation time (T₂₂ shifted from 2154.44 ms (0 h) to 1232.85 ms (9 h)), indicating that the water retention of fermented egg gels was enhanced. After fermentation, it could be seen intuitively that the porous structure of the gel surface almost disappeared, along with the improved springiness and brightness by texture and color measurement. This study suggested that moderate fermentation (L. plantarum 90, 1% v/v, 9 h) could effectively improve the gel property of LWE, and thus had a potential to expand the application of LWE in the food industry.     

The use of β-glucan as a partial salt replacer in high pressure processed chicken breast meat

The effect of various ingredients such as sodium chloride (NaCl), sodium tripolyphosphate (STPP) and β-glucan (BG) on the biochemical properties of chicken breast proteins during temperature assisted high pressure processing was studied. Total protein solubility revealed that 600 MPa pressure and 40 ^oC are critical for the denaturation of proteins in STPP samples. Increase in reactive sulfhydryl groups with pressure indicate the exposure of buried sulfhydryl groups. Hydrophobicity and sulfhydryl contents revealed that hydrophobic interaction and disulphide bond formation are responsible for gel formation. The study revealed that 40 ^oC and 400/600 MPa pressure is optimum for high pressure processing of chicken breast meat. Addition of β-glucan with reduced NaCl and in the absence of sodium tripolyphosphate could produce gels with similar properties to those with 2.5% NaCl addition. Hence it is proposed that β-glucan can be used to reduce NaCl content of chicken products produced by temperature assisted high pressure processing.     

Impact of carcass scalding and chilling on muscle proteins and meat quality of broiler breast fillets

The objective of this study was to determine the effects of broiler carcass scalding and chilling methods on meat quality and muscle proteins. During processing, carcasses were hard (60 °C, 1.5 min) or soft (52.8 °C, 3 min) scalded, and either immersion chilled (IC: 0.5 °C, 40 min) or air chilled (AC: 0.5 °C, 120 min). Breast fillets were deboned at 4 h postmortem and used for measuring meat quality and muscle protein characteristics. Scalding by chilling treatment interaction effects on meat quality were not observed. Air chilled carcasses had greater pH₂₄, and reduced drip loss and shear force compared to IC carcasses. Cook yield, color (L*a*b*), and moisture content were not different between chilling treatments. Scalding treatments did not influence quality traits. Sarcoplasmic protein solubility was not influenced by chilling treatment, but was greater in hard versus soft scalded carcasses. Myofibrillar protein solubility was greater in fillets from soft scalded IC carcasses. Alterations in the electrophoretic profiles of the myofibrillar and sarcoplasmic proteins due to treatments indicated minor changes in protein degradation and solubility. Data suggest that while only chilling method influenced meat quality, both scalding and chilling methods influenced protein solubility and degradation in breast fillets deboned 4 h postmortem.     

Peanut skins-fortified peanut butters: Effects on consumer acceptability and quality characteristics

Peanut skins (PS), high phenolics by-products from peanut processing, are potential functional ingredients. Effects of fortification with ground PS (3 types: dry-blanched, light- and medium-roasted) on peanut butter (PB) quality characteristics and consumer acceptability were evaluated. PS were added in concentrations of 0 (control), 2.5 and 5.0 g PS/100 g PB. Data were analyzed with Mixed Model ANOVA. Significant effects (P < 0.05) on product appearance and physical characteristics depended on level of incorporation and type of skins used; the greatest impact on objective appearance (L*, a*, b* color and particulate presence) and instrumental physical properties (spreadability and texture profile analysis parameters) occurred with incorporation of 5.0 g medium roasted PS/100 g PB. Consumer sensory panelists (P < 0.05) noted an increase in stiffness with incorporation of roasted PS at both levels, and less acceptable spreadability with incorporation of 5.0 g light or medium-roasted PS/100 g PB when compared to the control. Panelists also found PS addition affected acceptability of appearance more than flavor, texture or overall acceptability. With incorporation of 2.5 g PS/100 g PB, PS addition produced PBs that equaled the control in overall acceptability, regardless of heat treatment. At the 5.0 g PS/100 g PB incorporation level, PBs containing medium-roasted PS were less acceptable (P < 0.05) than all other formulations.