Effects of Cherry (Prunus cerasus L.) Powder Addition on the Physicochemical Properties and Oxidation Stability of Jiangsu-Type Sausage during Refrigerated Storage.

Effects of different levels (1%, 3% and 5%) of cherry powder on the physiochemical properties and antioxidant activity of Jiangsu-type sausages were investigated at 4 °C for 30 days. The results show that the sensory evaluation values and physicochemical properties of the sausages had no significant differences compared to the control group when cherry powder addition was 1%, and the alcohols, aldehydes and esters were increased after the addition of cherry powder improved the flavor of sausages. However, higher concentration of cherry powder (3% and 5%) exerted adverse influences on sensory evaluation values and physicochemical properties of sausages compared with the control. The addition of cherry powder could better inhibit lipid and protein oxidation of sausages, and the cherry powder concentration has a positive correlation with its effect on the inhibition of lipid and protein oxidation. In addition, cherry powder could effectively control TVB-N values of sausages during chilled storage. All these results indicate that 1% cherry powder could not only guarantee the physicochemical properties of sausages, but also inhibited the oxidation of sausages during chilled storage.

Casein and red meat proteins differentially affect the composition of the gut microbiota in weaning rats.

Casein and meat are food sources providing high-quality animal proteins for human consumption. However, little is known concerning potentially different effects of these animal protein sources during early stages of life. In the present study, casein and red meat proteins (beef and pork) were fed to young postweaning rats for 14 days based on the AIN-93G diet formula. Casein and red meat protein-based diets did not differentially affect the overall growth performance. However, they discriminately modulated the abundances of different potentially beneficial bacteria belonging to genus Lactobacillus. Intake of the casein-based diet increased the intestinal abundance of Lactococcus lactis with a pronounced potential for galactose utilization via the Tag6P pathway, and it also resulted in lower amounts of toxic ammonia in the rat cecum compared to red meat protein-based diets. We observed no adverse effects on colonic tissue in response to any of the protein-based diets based on histological observations.

Intake of a Chicken Protein-Based or Soy Protein-Based Diet Differentially Affects Growth Performance, Absorptive Capacity, and Gut Microbiota in Young Rats.

SCOPE: Both plant and animal products provide protein for human demands. However, the effect of protein sources on the physiological responses and the composition and functions of the gut microbiota during the early stage of life have received little attention. METHODS AND RESULTS: In the present study, chicken protein and soy protein are fed to young weaning rats for 14 days based on the AIN-93G diet formulation. The growth performance is recorded, and the morphology of the small intestine is analyzed to estimate the absorptive capacity. Shotgun metagenomic sequencing is applied to analyze the cecal microbiota. The chicken protein-based diet (CHPD) enhances growth performance and absorptive capacity in young rats compared to the soy protein-based diet (SPD). The CHPD maintains higher levels of Lactobacillus species, associated with glutathione synthesis. CONCLUSION: The CHPD seems favorable for young growing rats in relation to growth performance and absorptive capacity, correlated with changes in the composition and functional potential of the gut microbiota.

Effect of oxidation on the process of thermal gelation of chicken breast myofibrillar protein.

In this study, the effect of protein oxidation on the thermal gelation of chicken breast myofibrillar proteins (MPs) was investigated. MP samples treated with different degrees of oxidation were heated (1.5 °C/min) to different end-point temperatures to simulate the thermal gelation process. The results showed that the water-holding capacity (WHC) significantly decreased with increasing temperature, and higher oxidation degree resulted in worse WHC of heat-induced gel. Compared with high degrees of oxidation, low degrees of MP oxidation reduced the migration of immobile water, inhibited its release as free water, enhanced WHC and favored the formation of ß-sheet and ß-turn structures. Therefore, low oxidation promoted the formation of ß-sheet and ß-turn structures to form a better gel microstructure with less formation of free water on the thermal gelation and therefore increased the WHC. High oxidation was just the opposite, and high temperature aggravated this negative effect.

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.

High intake of chicken and pork proteins aggravates high-fat-diet-induced inflammation and disorder of hippocampal glutamatergic system.

High-fat diets have been associated with neurodegenerative diseases, which are also largely related to the type and amount of dietary proteins. However, to our knowledge, it is little known how dietary proteins affect neurodegenerative changes. In this study, we investigated the effects of dietary proteins in a high-fat diet on hippocampus functions related to enteric glial cells (EGCs) in Wistar rats that were fed either 40% or 20% (calorie) casein, chicken protein or pork protein for 12 weeks (n=10 each group). Inflammatory factors, glutamatergic system, EGCs, astrocytes and nutrient transporters were measured. A high-chicken-protein diet significantly increased the levels of systemic inflammatory factors, Tau protein and amyloid precursor protein mRNA level in the rat hippocampus. The type and level of dietary proteins in high-fat diets did not affect the gene expression of glial fibrillary acidic protein and α-synuclein (P>.05), indicating a negligible effect on astrocyte activity. However, the high-protein diets up-regulated glutamate transporters compared with the low-protein diets (P<.05), while they reduced the γ-aminobutyric acid content in high-chicken and -pork-protein diets (P<.05). Thus, compared with a low-protein diet (20%), a high-chicken or -pork-protein diet (40%) under a high-fat background could alter the balance between glutamatergic system and neurotransmitter and have a stronger effect on the interactions between hippocampal glutamatergic system and EGCs.

Effects of Casein, Chicken, and Pork Proteins on the Regulation of Body Fat and Blood Inflammatory Factors and Metabolite Patterns Are Largely Dependent on the Protein Level and Less Attributable to the Protein Source.

The impact of meat protein on metabolic regulation is still disputed and may be influenced by protein level. This study aimed to explore the effects of casein, pork, and chicken proteins at different protein levels (40% E vs 20% E) on body weight regulation, body fat accumulation, serum hormone levels, and inflammatory factors/metabolites in rats maintained on high-fat (45% E fat) diets for 84 d. Increased protein levels resulted in a significant reduction in body fat mass and an increase in the serum levels of the anti-inflammatory cytokine IL-10, independent of protein source. Analysis of blood via untargeted metabolomics analysis identified eight, four, and four metabolites significantly altered by protein level, protein source, and a protein level-source interaction, respectively. Together, the effects of casein, chicken, and pork protein on the regulation of body fat accumulation and blood metabolite profile are largely dependent on protein level and less attributable to the protein source.

High-Meat-Protein High-Fat Diet Induced Dysbiosis of Gut Microbiota and Tryptophan Metabolism in Wistar Rats.

Meat-diet-induced changes in gut microbiota are often accompanied with the development of various metabolic and inflammatory disorders. The exact biochemical mechanism underlying these effects is not well elucidated. This study aims to evaluate how meat proteins in high-fat diets affect tryptophan metabolism in rats. The high-chicken-protein (HFHCH) or high-pork-protein (HFHP) diets increased levels of skatole and indole in cecal and colonic contents, feces, and subcutaneous adipose tissue. The HFHCH and HFHP diets also increased the abundance of Lactobacillus, the Family XIII AD3011 group, and Desulfovibrio in the cecum and colon, which may be involved in the production of skatole and indole. Additionally, high-meat-protein diets induced lower activity of skatole- and indole-metabolizing enzyme CYP2E1 in liver compared with low-meat-protein diets. This work highlights the negative impact of high meat proteins on physiological responses by inducing dysbiosis of gut microbiota and tryptophan metabolism.

A Short-Term Feeding of Dietary Casein Increases Abundance of Lactococcus lactis and Upregulates Gene Expression Involving Obesity Prevention in Cecum of Young Rats Compared With Dietary Chicken Protein.

Casein and chicken are assessed to contain high quality proteins, which are essential for human health. Studies have shown that ingestion of the two dietary proteins resulted in distinct effects on physiology, liver transcriptome and gut microbiota. However, its underlying mechanism is not fully understood, in particular for a crosstalk between gut microbiota and host under a specific diet intervention. We fed young rats with a casein or a chicken protein-based diet (CHPD) for 7 days, and characterized cecal microbiota composition and cecal gene expression. We found that a short-term intervention with a casein-based diet (CAD) induced a higher relative abundance of beneficial bacterium Lactococcus lactis as well as Bifidobacterium pseudolongum, which upregulated galactose metabolism of the microbiome compared with a CHPD. The CAD also upregulated gene expression involved in obesity associated pathways (e.g., Adipoq and Irs1) in cecal tissue of rats. These genes and the bacterial taxon were reported to play an important role in protecting development of obesity. Furthermore, the differentially represented bacterial taxon L. lactis was positively associated with these differentially expressed genes in the gut tissue. Our results provide a new insight into the crosstalk between gut microbiota and host in response to dietary proteins, indicating a potential mechanism of obesity prevention function by casein.

Dietary Protein Sources Differentially Affect the Growth of Akkermansia muciniphila and Maintenance of the Gut Mucus Barrier in Mice.

SCOPE: The gut microbiota plays an essential role in linking diet to host health. The specific role of different dietary proteins on the gut microbiota and health is less understood. Here, the impact of proteins derived from chicken and soy on the gut microbiota and host gut barrier in C57BL/6 mice is investigated. METHODS AND RESULTS: Specific-pathogen-free and germ-free mice are assigned to either a chicken- or a soy protein-based diet for 4 weeks. Compared with a chicken-protein-based diet, intake of a soy-protein-based diet reduces the abundance of A. muciniphila and the number of goblet cells, lowers the level of Muc2 mRNA, and decreases the thickness of the mucus layer in the colon of specific-pathogen-free mice. In germ-free mice, colonization with A. muciniphila combined with intake of a chicken-protein-based diet results in a higher expression of the Muc2 mRNA in colon, and surprisingly, an increased potential for oxidative phosphorylation in A. muciniphila compared with colonized mice fed a soy-protein-based diet. CONCLUSION: These findings suggest possible mutually beneficial interactions between the growth and function of A. muciniphila and host mucus barrier in response to intake of a chicken-protein-based diet contrasting the intake of a soy-protein-based diet.

Effects of Oxidation in Vitro on Structures and Functions of Myofibrillar Protein from Beef Muscles.

The main purpose of this study was to investigate the effects of oxidation in vitro on the biochemical properties of myofibrillar protein isolates (MPIs) from beef muscles. MPIs were incubated at 4 °C for 24 h with hydroxyl-radical-generating systems consisting of 0.01 mM FeCl3 and 0.1 mM ascorbic acid plus 0, 0.2, 1, 5, 10, and 20 mM hydrogen peroxide. The results showed that oxidation caused drastically structural changes in bovine MPIs. The carbonyl content, the surface hydrophobicity, and the particle diameter of MPIs were significantly increased, while the free sulfhydryl group content was dramatically decreased with increasing hydrogen peroxide concentrations. Oxidation caused the protein aggregations through cross-linking between proteins and amino acids. Proteomics study identified protein sites in which they were easy to be oxidized. Oxidized catalytic activities and binding sites of enzymes that were susceptible to oxidation were also identified.

Purified Dietary Red and White Meat Proteins Show Beneficial Effects on Growth and Metabolism of Young Rats Compared to Casein and Soy Protein.

This study compared the effects of casein, soy protein (SP), red (RMP), and white meat (WMP) proteins on growth and metabolism of young rats. Compared to casein, the ratio of daily feed intake to daily body weight gain of rats was not changed by meat protein but reduced by SP by 93.3% ( P < 0.05). Feeding RMP and WMP reduced the liver total cholesterol (TC) contents by 24.3% and 17.8%, respectively ( P < 0.05). Only RMP increased plasma HDL-cholesterol concentrations (by 12.7%, P < 0.05), whereas SP increased plasma triacylglycerol, TC, and LDL-cholesterol concentrations by 23.7%, 19.5%, and 61.5%, respectively ( P < 0.05). Plasma essential and total amino acid concentrations were increased by WMP (by 18.8% and 12.4%, P < 0.05) but reduced by SP (by 28.3% and 37.7%, P < 0.05). Twenty-five liver proteins were differentially expressed in response to different protein sources. Therefore, meat proteins were beneficial for growth and metabolism of young rats compared to casein and SP.

Oxidative and anti-oxidative status in muscle of young rats in response to six protein diets.

We investigated the impact of six protein diets on oxidation and anti-oxidation status in the muscle of young rats. Rats were fed six protein diets for 14 days, including casein (control), and proteins isolated from soy, fish, chicken, pork and beef. Grx1, Trx1 and other oxidative metabolic indices in muscle were quantified. Compared with the casein diet, the soy protein diet had a similar oxidation level, but higher GSH and lower SOD activities. The chicken and fish protein groups had lower GSH and higher SOD activities, the pork protein group showed lower Grx1 levels than the casein group and the beef protein group showed the highest GSH, Grx1 and Trx1 levels as reflected by RT-PCR, Western blotting and immunohistochemistry analyses. Intake of meat proteins showed higher ROS and T-AOC but lower MDA levels than non-meat proteins, which may be due to the increase in Grx1 and Trx1 expression and other antioxidants. Meat proteins are more conducive to muscle of growing rats.

Erratum: Fish oil, lard and soybean oil differentially shape gut microbiota of middle-aged rats.

A correction to this article has been published and is linked from the HTML version of this paper. The error has been fixed in the paper.

Fish oil diet may reduce inflammatory levels in the liver of middle-aged rats.

The impact of dietary soybean oil, lard and fish oil on physiological responses in middle age is little studied. In this study, we investigated the changes of oxidative stress, inflammatory cytokines, telomere length, and age-related gene expression in the liver of middle-aged rats in response to the above three fat diets. Male Sprague Dawley rats (12 months old) were fed AIN-93M diets for 3 months, in which soybean oil was equivalently replaced by lard or fish oil. As compared to the lard diet, intake of fish oil diet significantly decreased body weight gain, white blood cell count, and levels of hepatic triacylglycerol, total cholesterol, fat accumulation, low-density lipoprotein, oxidative stress and inflammatory cytokines (P < 0.05), but increased telomere length (P < 0.05). On the other hand, lard diet and soybean oil diet showed great similarity in the above variables. PCR array analysis further indicated that fish oil diet significantly down-regulated gene expression related to inflammatory response, apoptosis, DNA binding, proteostasis and telomere attrition. Differentially expressed genes were enriched in the complement and coagulation cascades pathways. Such physiological and molecular responses could be due to different fatty acid composition in fish oil, lard and soybean oil.

Fish oil, lard and soybean oil differentially shape gut microbiota of middle-aged rats.

High-fat diets have been associated with overweight/obesity and increased mortality in middle-aged populations. However, it is still unclear how gut microbiota in middle-aged populations responds to dietary fats at a normal dose. In this study, we explored gut microbiota structure in middle-aged rats (aged 12 months) after feeding 4% (w/w) soybean oil, lard or fish oil for 3 months, respectively. The results showed that the gut microbiota structure in the fish oil group was substantially different from those of the soybean oil and lard groups in both in vitro and in vivo studies. The relative abundances of phylum Proteobacteria and genus Desulfovibrio in the caecal and colonic contents were the highest in the fish oil group (p < 0.05). The mRNA levels of biomarkers for inflammation in the colon, including IL-1ß, IL-6, IL-17, IL-18 and TNF-α, were also the highest in the fish oil group (p < 0.05). Meanwhile, the fish oil group had the highest microbial DNA abundance of a predicted lipid metabolism. Our results gave a new insight into the potentially negative impact of fish oil diet on health of middle-aged populations by changing gut microbiota and inducing inflammation as compared to soybean oil and lard diets.

Meat proteins had different effects on oligopeptide transporter PEPT1 in the small intestine of young rats.

The peptide transporter 1 (PEPT1) in the apical membrane of enterocytes is the central mechanism for regulating the absorption of di- and tripeptides. Dietary proteins may affect PEPT1 abundance and peptide absorption. The present study aimed to characterize changes in PEPT1 mRNA and PEPT1 protein levels in the duodenum and jejunum of young rats after 7-day diet intervention with casein (reference), soy, beef, pork, chicken and fish proteins and further evaluate the impact on the epithelial absorption capacity. RT-PCR and western blot analyses showed that: (1) PEPT1 protein level in duodenum was higher (p < 0.05) for soy protein group than that for casein group. However, no difference was observed in jejunal PEPT1 protein level between any two diet groups (p > 0.05). The soy protein group had lower crypt depth and higher V/C ratio in the jejunum (p < 0.05). (2) PEPT1 mRNA levels were lower (p < 0.05) in rat duodenum and jejunum in pork, chicken and fish protein groups, whose trend was contrary to the results of jejunual histological observation with lower crypt depth, greater villus height and higher V/C ratio. In conclusion, different meat proteins alter distinct PEPT1 expression level and absorption capacity as reflected by gut morphology in small intestine.

Dietary soy and meat proteins induce distinct physiological and gene expression changes in rats.

This study reports on a comprehensive comparison of the effects of soy and meat proteins given at the recommended level on physiological markers of metabolic syndrome and the hepatic transcriptome. Male rats were fed semi-synthetic diets for 1 wk that differed only regarding protein source, with casein serving as reference. Body weight gain and adipose tissue mass were significantly reduced by soy but not meat proteins. The insulin resistance index was improved by soy, and to a lesser extent by meat proteins. Liver triacylglycerol contents were reduced by both protein sources, which coincided with increased plasma triacylglycerol concentrations. Both soy and meat proteins changed plasma amino acid patterns. The expression of 1571 and 1369 genes were altered by soy and meat proteins respectively. Functional classification revealed that lipid, energy and amino acid metabolic pathways, as well as insulin signaling pathways were regulated differently by soy and meat proteins. Several transcriptional regulators, including NFE2L2, ATF4, Srebf1 and Rictor were identified as potential key upstream regulators. These results suggest that soy and meat proteins induce distinct physiological and gene expression responses in rats and provide novel evidence and suggestions for the health effects of different protein sources in human diets.

Comparative Proteomics Provides Insights into Metabolic Responses in Rat Liver to Isolated Soy and Meat Proteins.

It has been reported that isolated dietary soy and meat proteins have distinct effects on physiology and liver gene expression, but the impact on protein expression responses are unknown. Because these may differ from gene expression responses, we investigated dietary protein-induced changes in liver proteome. Rats were fed for 1 week semisynthetic diets that differed only regarding protein source; casein (reference) was fully replaced by isolated soy, chicken, fish, or pork protein. Changes in liver proteome were measured by iTRAQ labeling and LC-ESI-MS/MS. A robust set totaling 1437 unique proteins was identified and subjected to differential protein analysis and biological interpretation. Compared with casein, all other protein sources reduced the abundance of proteins involved in fatty acid metabolism and Pparα signaling pathway. All dietary proteins, except chicken, increased oxidoreductive transformation reactions but reduced energy and essential amino acid metabolic pathways. Only soy protein increased the metabolism of sulfur-containing and nonessential amino acids. Soy and fish proteins increased translation and mRNA processing, whereas only chicken protein increased TCA cycle but reduced immune responses. These findings were partially in line with previously reported transcriptome results. This study further shows the distinct effects of soy and meat proteins on liver metabolism in rats.

Distinct physiological, plasma amino acid, and liver transcriptome responses to purified dietary beef, chicken, fish, and pork proteins in young rats.

SCOPE: We report on the impact of purified dietary meat proteins from four species on plasma insulin, lipid and amino acid (AA) concentrations, and hepatic transcriptome (RNA-sequencing). METHODS AND RESULTS: Young rats received semi-synthetic diets for 1 wk that differed only regarding protein source; casein (reference) was replaced by beef, chicken, fish, or pork proteins. Compared to casein, all proteins, except pork, increased total plasma AA concentrations. Pork protein reduced adipose tissue mass and liver triacylglycerol, which was accompanied by increased plasma triacylglycerol concentrations. Plasma cholesterol was reduced by fish protein. The number of differentially expressed genes ranged between 609 (pork) and 1258 (chicken); on average one-third of the changes were specific for each meat protein. Pathway responses were most similar for beef and chicken, followed by pork and fish. Although the extent varied, all meat proteins induced mRNA translation, antigen processing/presentation, intracellular vesicular trafficking, and oxidoreductive-transformation pathways, and suppressed signal-transduction (Notch, TGFB/SMAD, insulin) and mitochondrial biogenesis pathways. Lipid- and AA-metabolic pathways were repressed, except by pork. AA-transport pathways were induced by beef and fish only, and complement/coagulation-pathways were suppressed by chicken and beef. Fish suppressed nuclear-transport and cofactor metabolism. CONCLUSION: To conclude, short-term feeding of different meat proteins resulted in distinct physiological and transcriptome changes in young rats.