Replacement of backfat with vegetable oils or their oleogels in emulsion-type sausage significantly change the digestibility of meat protein.

Replacing animal fat with vegetable oil occurred extensively in the meat products, but whether these replacements will affect the nutrition of meat protein was seldom revealed. Effect of substitution of back fat (BF) by vegetable oils or their oleogels in emulsion-type sausage on the digestion process of meat protein was investigated. Replacement of BF with vegetable oils and their oleogels decreased the G'/G" values of meat paste, and oleogels largely weakened the structure of sausages. The substitution significantly reduced the liberation of -NH2 during the initial gastric and intestinal digestion, and resulted in bigger digests in CLSM images. The reduced gastric digestibility induced by substitution was shown to be related to the reduced stability of gastric digests, which can be attributed to the larger particle size and reduced viscosity of digests. These results highlighted stability of digests as a key point changing the digestion process of meat protein.

Effect of Non-Meat Proteins on Storage Characteristics and Amino Acid Composition of Pork Emulsified Sausages.

This study was conducted to confirm the following effects of non-meat binders (NMB) on proximate composition, pH, cooking yield, amino acids, volatile basic nitrogen (VBN), thiobarbituric acid reactive substance (TBARS), and correlation of pork emulsified sausages during refrigerated storage. The following groups of sausage samples were manufactured: Control (non-addition), BBP (1% bovine blood plasma); PBP (1% porcine blood plasma), EWP (1% white egg powder), CPPP (1% commercial porcine plasma powder), ISP (1% isolated soy protein), SP (1% seaweed powder), and SC (1% sodium caseinate). When NMB was added, ISP, SP, and SC showed higher heating yields while PBP showed lower heating yields than the control. As a result of amino acid analysis, PBP, CPPP, and SC showed significantly higher serine content than the control. EWP and SC showed significantly lower TBARS values than the control group, and VBN did not exceed 20 mg% in any treatments until the 5th week. These results demonstrate that SC is a NMB that can lower TBARS value while improving heating yield and serine content.

Interaction of pepper numbing substances with myofibrillar proteins and numbness perception under thermal conditions: A structural mechanism analysis.

This study examined the interaction between myofibrillar proteins (MPs) and the numbing substance hydroxy-α-sanshool (α-SOH) in a thermal environment, and provided an explanation of the numbness perception mechanism through muti-spectroscopic and molecular dynamics simulation methodology. Results showed that addition of α-SOH could reduce the particle size and molecular weight of MPs, accompanied by changes in the tertiary and secondary structure, causing the α-helix of MPs transitioned to ß-sheet and ß-turn due to the reorganization of hydrogen bonds. After a moderate heating (60 or 70 °C), MPs could form the stable complexes with α-SOH that were associated with attachment sites and protein wrapping. The thermal process might convert a portion of α-SOH' into hydroxy-ß-sanshool' (ß-SOH'). When docking with the sensory receptor TRPV1, the RMSD, RMSF and binding free energy all showed that ß-SOH' demonstrated a low affinity, thereby reducing the numbing perception. These findings can provide a theoretical foundation for the advanced processing of numbing meat products.

Measuring water holding capacity in poultry meat.

In the current scientific literature, one can find >100 different methods to evaluate water-holding capacity in fresh and cooked meat. The main concepts are based on removing some of the water by either gravity, application of pressure (e.g., centrifugal force), and heating while measuring water exudate to predict the water holding capacity (WHC) during storage, processing, cooking, and/or distribution. More sophisticated methods include nuclear magnetic resonance (NMR) in which the relaxation of water molecules within a meat protein/gel system is measured to predict how the water (75% in lean meat) will behave during processing. Overall, the number of tests reported is also so high because there are quite big variations in test conditions (e.g., 750-30,000 g for centrifugal testing). The aim of this article (outcome of a symposium on methods for poultry meat characterization) is to help the reader navigate through the different setups and suggest standardized testing based on scientific principles. The recommended WHC test is the application of low centrifugal force (750 g so sample is not permanently deformed) to a protein gel, while the sample is placed on a screen platform to avoid reabsorbing the liquid separating during the slowing down of the centrifuge. It is also recognized that some meat samples (e.g., high in fat) might require a different g-force, so it is recommended to employ both the conditions mentioned above and the lab-specific conditions. Our overall goal should always be to increase uniformity in test procedures, which will enhance our capabilities to compare results among research groups.

Interaction of the extracellular protease from Staphylococcus xylosus with meat proteins elucidated via spectroscopic and molecular docking.

This study aimed to assess the effect of an external protease secreted by Staphylococcus (S.) xylosus on the hydrolysis and flavor properties of meat protein. The results indicated that the protease significantly increased the solubility of myofibrillar proteins (MPs) and sarcoplasmic proteins (SPs) in water (P < 0.05), and altered their surface hydrophobicity and secondary structure. The results of micromorphological and free amino acids analyses suggested that the protease degraded the large and insoluble meat protein aggregates into small molecular proteins with uniform distribution and amino acids, especially glycine, glutamic acid, leucine, and cysteine. Moreover, the protease-catalyzed hydrolysis promoted the formation of some volatile compounds in the MPs and SPs. Additionally, molecular docking analysis suggested that hydrogen bond and hydrophobic interaction promoted the formation of a S. xylosus protease/meat protein complex. These results provided a basis for the future application of S. xylosus protease in meat products.

Thermal Characterisation and Isoconversional Kinetic Analysis of Osmotically Dried Pork Meat Proteins Longissimus dorsi.

The kinetic properties and thermal characteristics of fresh pork meat proteins (Longissimus dorsi), as well as osmotically dehydrated meat proteins, were investigated using differential scanning calorimetry. Two isoconversional kinetical methods, namely the differential Friedman and integral Ortega methods, were employed to analyze the data. The obtained kinetic triplet, activation energy, pre-exponential factor, and extent of conversion, has been discussed. The resulting activation energy for proteins of fresh meat ranges between 751 kJ·mol-1 for myosin, 152 kJ·mol-1 for collagen and sarcoplasmic proteins, and 331 kJ·mol-1 for actin at a conversion degree of 0.1 to 0.9. For osmotically dried pork meat proteins, the values range from 307 kJ·mol-1 for myosin 272 kJ·mol-1 for collagen and sarcoplasmic proteins, and 334.83 kJ·mol-1 for actin at a conversion degree from 0.1 to 0.9. The proteins of the dry meat obtained by osmotic dehydration in molasses could be described as partly unfolded as they retain the characteristic protein denaturation transition. Concerning the decrease in enthalpies of proteins denaturation, thermodynamic destabilization of dried meat proteins occurred. On the contrary, dried meat proteins were thermally stabilized with respect to increase in the temperatures of denaturation. Knowledge of the nature of meat protein denaturation of each kind of meat product is one of the necessary tools for developing the technology of meat product processing and to achieve desired quality and nutritional value. The kinetic analysis of meat protein denaturation is appropriate because protein denaturation gives rise to changes in meat texture during processing and directly affects the quality of product.

Increased Dietary Intakes of Total Protein, Animal Protein and White Meat Protein Were Associated with Reduced Bone Loss-A Prospective Analysis Based on Guangzhou Health and Nutrition Cohort, South China.

In this study, we aimed to prospectively investigate the relationships between different types of dietary protein and changes in bone mass in Chinese middle-aged and elderly people. Dietary intakes were evaluated by means of a validated food frequency questionnaire. Bone mineral density (BMD) was measured using a dual-energy bone densitometer at multiple bone sites. Multivariable regression models were applied to investigate the associations of the participants' dietary intakes of total protein, intakes of protein from various sources, and amino acid intakes with the annualized changes in BMD during a 3-year follow-up. A total of 1987 participants aged 60.3 ± 4.9 years were included in the analyses. Multivariable linear regression results showed that dietary intakes of total protein, animal protein, and protein from white meat were positively correlated with BMD changes, with standardized coefficients (ß) of 0.104, 0.073, and 0.074 at the femur neck (p < 0.01) and 0.118, 0.067, and 0.067 at the trochanter (p < 0.01), respectively. With each increase of 0.1g·kg-1·d-1 in animal protein and white meat protein intakes, the BMD losses were reduced by 5.40 and 9.24 mg/cm2 at the femur neck (p < 0.05) and 1.11 and 1.84 mg/cm2 at the trochanter (p < 0.01), respectively. Our prospective data, obtained from Chinese adults, showed that dietary total and animal protein, especially protein from white meat, could significantly reduce bone loss at the femur neck and trochanter.

Phosphate alternatives for meat processing and challenges for the industry: A critical review.

Meat and meat products provide high levels of nutrition and many health benefits to consumers, yet a controversy exists regarding the use of non-meat additives, such as the inorganic phosphates that are commonly used in meat processing, and particularly their relationship to cardiovascular health and kidney complications. Inorganic phosphates are salts of phosphoric acid (e.g., sodium phosphate, potassium phosphate, or calcium phosphate), whereas organic phosphates are ester compounds (e.g., the phospholipids found in cell membranes). In this sense, the meat industry remains active in its efforts to improve formulations for processed meat products with the use of natural ingredients. Despite efforts to improve formulations, many processed meat products still contain inorganic phosphates, which are used for their technological contributions to meat chemistry including improvements in water-holding capacity and protein solubilization. This review provides a thorough evaluation of phosphate substitutes in meat formulations and other processing technologies that can help eliminate phosphates from the formulations of processed meat products. In general, several ingredients have been evaluated as replacements for inorganic phosphates with varying degrees of success such as plant-based ingredients (e.g., starches, fibers, or seeds), fungi ingredients (e.g., mushrooms and mushroom extracts), algae ingredients, animal-based ingredients (e.g., meat/seafood, dairy, or egg materials), and inorganic compounds (i.e., minerals). Although these ingredients have shown some favorable effects in certain meat products, none have exactly matched the many functions of inorganic phosphates, so the support of extrinsic technologies, such as tumbling, ultrasound, high-pressure processing (HPP), and pulsed electric field (PEF), may be necessary to achieve similar physiochemical properties as conventional products. The meat industry should continue to investigate ways to scientifically innovate the formulations of, and the technologies used in, processed meat products while also listening to (and acting upon) the feedback from consumers.

Effect of Pork Skin Gelatin on the Physical Properties of Pork Myofibrillar Protein Gel and Restructured Ham with Microbial Transglutaminase.

The goal of this study was to determine the qualities of pork myofibrillar protein (MP) gels added with pork gelatin and transglutaminase (TGase), as well as their application to restructured ham (RH). MP mixtures were prepared with various levels of gelatin (0.5, 1.0, and 1.5%. w/w) and TGase. In this study, cooking loss (CL), gel strength, shear stress, and the microstructure of MP with various levels of gelatin were evaluated. After RHs were manufactured with varying levels of gelatin and TGase, the physicochemical and textural properties were measured. The CL of the MP with 1% (w/w) of gelatin was decreased. Regardless of the presence of TGase, increased amounts of gelatin in the MP gels resulted in high shear stress. Shear values were higher in the RH with gelatin treatment than in the other treatments. In addition, the RHs with gelatin alone or combined with TGase had high water-holding capacity. The RH with the combination of gelatin and TGase had higher sensory attributes than the control. Gelatin improved the physical properties of the RHs and is recommended for application in various meat products.

Lower Non-Heme Iron Absorption in Healthy Females from Single Meals with Texturized Fava Bean Protein Compared to Beef and Cod Protein Meals: Two Single-Blinded Randomized Trials.

Meat analogs based on plant protein extracts are rising in popularity as meat consumption declines. A dietary shift away from meat, which has a high iron bioavailability, may have a negative effect on the amount of iron absorbed from the diet. Iron absorption from legumes cultivated in regions not suitable for soy production, such as fava bean, has not yet been explored. The aim of this study was to evaluate non-heme iron absorption from a meal with texturized fava bean protein compared to beef and cod protein meals. The study included two single-blinded iron isotope trials in healthy Swedish women of the ages 18-45 years, each of whom served as their own control. The participants were served matched test meals containing beef and fava bean protein (Study 1) or cod and fava bean protein (Study 2) with radiolabeled non-heme iron 55Fe and 59Fe. The absorption of non-heme iron from test meals was measured by whole-body counting and erythrocyte incorporation. The absorption of non-heme iron, measured as erythrocyte incorporation ratio, from beef protein meal was 4.2 times higher compared to texturized fava bean meal, and absorption from cod protein meal was 2.7 times higher compared to the fava bean meal. The adjusted non-heme iron absorption, normalized to a 40% reference dose uptake, was 9.2% for cod protein meal, 21.7% for beef protein meal, and 4.2% for texturized fava bean meal. A fava bean protein meal has markedly lower iron bioavailability in healthy females compared with a meal of beef or cod protein. Therefore, a dietary shift from meat and fish protein to fava bean protein may increase the risk of iron deficiency.

Purification and Characterization of the Protease from Staphylococcus xylosus A2 Isolated from Harbin Dry Sausages.

The protease generated from Staphylococcus (S.) xylosus A2, which was isolated from Harbin dry sausages, was purified and characterized. The molecular weight of the purified protease was approximately 21.5 kDa, and its relative activity reached the highest at pH 6.0 and 50 °C. At pH 4.0−8.0 and temperatures of 20−50 °C, the protease was stable. Its activity was significantly improved by Ca2+ and Zn2+ ions (p < 0.05). The Michaelis constant and maximum velocity of the protease were 2.94 mg/mL and 19.45 U/mL·min, respectively. The thermodynamic parameters analysis suggested that the protease showed better catalytic properties at 40 °C. Moreover, the protease could hydrolyze meat proteins, and obtained hydrolysate is non-cytotoxic to the HEK-293 cells. These findings provide a theoretical basis for understanding the enzymatic characterization of S. xylosus A2 protease and its future application in fermented meat products.

Airborne ultrasonic application on hot air-drying of pork liver. Intensification of moisture transport and impact on protein solubility.

Nowadays, there is increasing interest in developing strategies for the efficient and sustainable use of animal by-products, such as pork liver. In order to stabilize the product, a prior dehydration stage may be required due to its high perishability. The water removal process of pork liver is energy costly and time consuming, which justifies its intensification using novel technologies. In this sense, the aim of this study was to assess the effect of the airborne application of power ultrasound on the hot air-drying of pork liver. For that purpose, drying experiments were carried out at 30, 40, 50, 60 and 70 °C on pork liver cylinders at 2 m·s-1 with (US) and without ultrasonic application (AIR). The drying process was modeled from the diffusion theory and, in the dried pork liver, the protein solubility was analyzed in order to determine the effect of drying on the protein quality. The ultrasound application increased the drying rate, shortening the drying time by up to 40% at 30 °C. The effect of power ultrasound at high temperatures (60 and 70 °C) was of lesser magnitude. Drying at 70 °C involved a noticeable reduction in the protein solubility for dried liver, while the impact of ultrasound application on the solubility was not significant (p > 0.05).

Ultrasound treatment can increase digestibility of myofibrillar protein of pork with modified atmosphere packaging.

We explored whether ultrasound treatment affected digestibility of myofibrillar protein (MP) isolated from modified atmosphere packed (MAP, 70% N2 and 30% CO2) pork. MP digestibility under pepsin and pancreatin treatments decreased significantly with storage time. Ultrasound treatment increased the digestibility and produced a greater number of smaller peptides. However, the total peptide count and unique peptide counts were significantly reduced. Moreover, active sulfhydryl, total sulfhydryl, particle size, turbidity and surface hydrophobicity of MP increased with time, while protein solubility and ATPase activity decreased. Compared with the untreated samples, ultrasound treatment increased protein solubility, surface hydrophobicity, and active sulfhydryl content, but decreased total sulfhydryl content (except 10 d), particle sizes, turbidity and ATPase activity. Ultrasound treatment resulted in a decline in ß-turn and α-helix contents. Therefore, ultrasound is conducive to the digestion. Additionally, structural and functional properties of protein in MAP were less stable than those in vacuum-packed pork reported before.

White meat proteins were more conducive to hepatic antioxidative status than soybean and red meat proteins.

Intake of protein-rich foods might induce oxidative stress in organs. This study investigated the impacts of protein sources including casein, soybean, fish, chicken, pork, and beef proteins on hepatic oxidation and antioxidation status in rats. It was shown that meat proteins produced higher reactive oxygen species in livers (from 64,868 to 87,153 F/mgpro) than casein (54,045 F/mgpro) and soybean protein (48,361 F/mgpro, p < .05). Pork and soybean proteins induced higher hepatic oxidative stress than fish, chicken and beef proteins by increasing malondialdehyde production (>16%, p < .05). White meat (fish and chicken) proteins promoted hepatic superoxide dismutase activity and total antioxidant capacity compared to soybean and red meat (pork and beef) proteins (p < .05). Compared to red meat proteins, white meat proteins increased hepatic expressions of thioredoxin and glutaredoxin. Rats fed red meat proteins showed hepatic steatosis with small vacuoles. Therefore, white meat proteins were more conducive to hepatic antioxidative status than soybean and red meat proteins. PRACTICAL APPLICATIONS: Intake of protein-rich foods may induce oxidative stress response at both cell and organ levels. The objective of this study was to investigate the impacts of different protein sources including casein, soybean, fish, chicken, pork, and beef proteins on oxidation and antioxidation status in rat livers. It was shown that meat proteins induced higher production of reactive oxygen species than casein and soybean protein. However, white meat proteins showed higher antioxidant capacity than soybean and red meat proteins by increasing hepatic superoxide dismutase activity and total antioxidant capacity. Therefore, compared to soybean and red meat proteins, white meat proteins lowered hepatic oxidative stress by reducing malondialdehyde production. This study suggested that intake of moderate white meat proteins was more conducive to hepatic antioxidative status than intake of soybean and red meat proteins. This study would promote the understanding of healthy effects of different protein sources.

Chemical, technological, instrumental, microstructural, oxidative and sensory properties of emulsified sausages formulated with microparticulated whey protein to substitute animal fat.

The current study was conducted to investigate the utilization of microparticulated whey protein (MWP) in different levels (5% or 10%) as partial fat replacers in emulsified beef sausage formulations. Inclusion of MWP resulted in sausages having decreased amounts of fat and energy while increased amounts of protein. Both emulsion stability and processing yield were the highest in samples containing MWP. No differences were recorded in L* values of the sausages although both a* and b* values were higher in MWP sausages than in full-fat sausages regardless of MWP level. Increased amounts of MWP led to lower hardness, chewiness and adhesiveness. Micrographs brought out the organized and reticulated structure of the sausages containing 10% MWP. MWP did not cause unfavorable impacts in general sensory acceptance, besides, it was associated with increased oxidative stability. Overall, the findings highlighted the favorable effects of MWP in terms of nutritional, technological, sensory and oxidative quality indicating the possibility to design low-fat emulsified meat product formulations.

Higher Animal Protein Intake During the Second Trimester of Pregnancy Is Associated With Risk of GDM.

Background and Aims: This study aimed to examine the associations between the total protein intake as well as types and sources of proteins with the gestational diabetes mellitus (GDM) risk. Method and Results: This was a prospective cohort study of the pregnant women in Malaysia. In this study, the total, animal, and plant protein intakes were assessed using a semi-quantitative food frequency questionnaire. Of the 452 women, 48 (10.62%) were diagnosed with GDM. From pre-pregnancy to second trimester, most of the women had 10-20% of energy intake from protein (88.9-90.3%) and ≥75% of recommended protein intake (74.6-86.5%). The women in the highest tertile (T3) of total animal protein intake [adjusted odds ratio (AOR) = 2.76, 95% CI = 1.27-6.04] and red meat protein (AOR = 2.69, 95% CI = 1.27-5.70), specifically in the second trimester, had significantly higher GDM risk compared with the women in the middle tertile of intake (T2). Interestingly, the women in the T3 of egg protein in the second trimester were significantly at lower GDM risk (AOR = 0.43, 95% CI = 0.18-0.91) compared with those in T2. Conclusion: The highest tertile of animal protein (≥42.15 g/day) intake, particularly red meat protein in the second trimester was positively associated with the GDM risk, whereas the highest tertile of egg protein was inversely associated with the GDM risk. Protein intake before or during early pregnancy was not associated with the GDM risk. These findings underscore the importance of sources and types of protein intake, particularly after the first trimester of pregnancy, in relation to GDM risk.

Replacement of Meat with Non-Meat Protein Sources: A Review of the Drivers and Inhibitors in Developed Countries.

The overconsumption of meat has been charged with contributing to poor health and environmental degradation. Replacing meat with non-meat protein sources is one strategy advocated to reduce meat intake. This narrative review aims to identify the drivers and inhibitors underlying replacing meat with non-meat protein sources in omnivores and flexitarians in developed countries. A systematic search was conducted in Scopus and Web of Science until April 2021. In total, twenty-three studies were included in this review examining personal, socio-cultural, and external factors. Factors including female gender, information on health and the environment, and lower price may act as drivers to replacing meat with non-meat protein sources. Factors including male gender, meat attachment, food neophobia, and lower situational appropriateness of consuming non-meat protein sources may act as inhibitors. Research is needed to establish the relevance of socioeconomic status, race, ethnicity, religion, health status, food environment, and cooking skills. Future studies should prioritize standardizing the definitions of meat and non-meat protein replacements and examining factors across different consumer segments and types of non-meat protein sources. Thereby, the factors determining the replacement of meat with non-meat protein sources can be better elucidated, thus, facilitating the transition to a healthier and more sustainable diet.

Effects of Ultrasound-Assisted Emulsification on the Emulsifying and Rheological Properties of Myofibrillar Protein Stabilized Pork Fat Emulsions.

The current study aimed to investigate the effects of ultrasound-assisted emulsification on the emulsifying and rheological properties of myofibrillar protein (MP) pork fat emulsions under different protein/fat ratios. Changes in emulsion profile, confocal laser scanning microscope images, cryo-scanning microscope images, particle size, protein solubility, surface hydrophobicity and free sulfhydryl groups were determined. Ultrasound significantly increased the emulsifying activity, the emulsifying stability and the flow index for all emulsions, while it decreased the viscosity coefficient of emulsions except for the treatment of protein/fat ratio of 1:15. The results showed that sonication reduced the particle size of the fat particles and evenly distributed the emulsion droplets. Sonication moved the distribution curve of droplet size to the smaller particle size direction and decreased the D3,2 and D4,3 values of emulsion. Sonication resulted in increased bindings between protein hydrophobic groups and fat particles. After ultrasound treatment, more sulfhydryl groups were exposed to aqueous solution, which might decrease the protein solubility in aqueous solution. Ultrasound-assisted emulsification could directly enhance the emulsifying and rheological properties of MP-stabilized pork fat emulsions at different protein/fat ratios, in particular at the ratio of 1:10.

Improvement of meat protein digestibility in infants and the elderly.

Meat is a valuable protein source with a balanced composition of essential amino acids and various nutrients. This review aims to identify methods to improve digestion of meat proteins, as well as evaluate the digestive characteristics of infants and the elderly. Immature digestive conditions in infants, including a high gastric pH and low protease concentration, can hinder protein digestion, thus resulting in inhibited growth and development. Likewise, gastrointestinal (GI) tract aging and chronic health problems, including tooth loss and atrophic gastritis, can lead to reduction in protein digestion and absorption in the elderly compared with those in young adults. Moderate heating and several non-thermal technologies, such as aging, enzymatic hydrolysis, ultrasound, high-pressure processing, and pulsed electric field can alter protein structure and improve protein digestion in individuals with low digestive capacity.

Biochemical properties of extracellular protease from Staphylococcus carnosus RT6 isolated from Harbin dry sausages, and its hydrolysis of meat proteins.

The characteristics of the extracellular protease, produced by Staphylococcus carnosus RT6 isolated from Harbin dry sausages, and its hydrolysis of meat proteins were investigated. The protease was purified by ammonium sulfate, ion exchange, and gel filtration chromatography to obtain a 20.0 kDa extracellular protease. The protease reached maximal activity at pH 9.0 and 50 °C and was stable at pH 7.0 to 11.0 and 20 to 40 °C. Its protease activity was easily inhibited in the presence of Zn2+ , Fe2+ , and Fe3+ . The enzymatic characterization of the protease revealed a Vmax 49.50 U/ml·min, Km 8.19 mg/ml, and the half-life = 28.06 min, ΔH* d  = 114.11 kJ/mol, ΔG* d  = 89.24 kJ/mol, and ΔS* d  = 77.00 J/mol·K at 50 °C. In addition, the protease hydrolyzed meat protein into small particles and produced soluble peptides. This study provides a basis for understanding the biochemical characteristics of the S. carnosus RT6 protease and its future application for fermented meat products.