Exploring the unknowns involved in the transformation of muscle to meat

Meat quality development, or the transformation of muscle to meat, involves a myriad of biochemical pathways that are largely well-studied in living muscle tissue. However, these pathways are less predictable when homeostatic ranges are violated. In addition, there is far less known about how various management or environmental stimuli impact these pathways, either by substrate load or altered cellular environment. Likewise, it is largely accepted that oxygen plays little to no role in the conversion of muscle to meat, as anaerobic metabolism predominates in the muscle tissue. Even so, the oxygen tension within the tissues does not fall precipitously at exsanguination. Therefore, transition to an anaerobic environment may impact energy metabolism postmortem. Antemortem handling, on the other hand, clearly impacts meat quality development, yet the exact mechanisms remain a mystery. In this paper, we will attempt to review those factors known to affect postmortem energy metabolism in muscle and explore those areas where additional work may be fruitful.     

Matrix effects on the bioavailability of resveratrol in humans

The pharmacokinetics of resveratrol in 11 healthy male volunteers has been assessed in a randomized, crossover, controlled clinical trial after the administration of three grape products: red wine (250 mL), grape juice (1/L), or tablets (red wine extracts enriched with trans-resveratrol). Doses of trans-resveratrol independently of the product administered, were about 14 μg/kg. Biological samples were collected and analysed by capillary gas chromatography–mass spectrometry. cis-Resveratrol, trans-resveratrol and dihydroresveratrol were determined in plasma and urine. Plasma concentration of trans-resveratrol after hydrolysis increased as a response to all grape products and that of cis-resveratrol after wine and grape juice. Free forms of these phenolic compounds were deemed undetectable in plasma. Despite similar trans-resveratrol doses being administered, its bioavailability from wine and grape juice was 6-fold higher, than that from tablets. Resveratrol was better absorbed from natural grape products than from tablets, pointing out the importance of the matrix in its bioavailability.     

Feeding microalgae at a high level to finishing heifers increases the long‐chain n‐3 fatty acid composition of beef with only small effects on the sensory quality

The aim of the study was to determine the effect of feeding a low and high level of microalgae (MA, high in C22:6n‐3) on the fatty acid (FA) composition and sensory attributes of beef. Thirty Charolais cross Limousin/Friesian heifers were fed one of the three diets (n = 10 per treatment): Control (no MA), low MA (LMA; inclusion rate of 15 g kg^?1) or high MA (HMA; inclusion rate of 30 g kg^?1) for 95 days before slaughter. Heifers fed HMA had a higher (P < 0.05) content of C20:5n‐3: eicosapentaenoic acid (EPA) and C22:6n‐3: docosahexaenoic acid (DHA) in the longissimus thoracis muscle than those receiving the Control (mean values for EPA of 0.5, 0.92, 1.20 and DHA of 0.31, 0.89 and 1.05 % of total FA for Control, LMA and HMA, respectively), and a lower n‐3 to n‐6 ratio (2.9, 1.9 and 1.6 in Control, LMA and HMA, respectively; P < 0.001). Steaks from animals fed either of the MA diets had a marginally higher (P < 0.05) ‘seaweedy flavour’ that was positively correlated with muscle C22:6n‐3 concentration. Steaks from animals fed HMA were rated as being higher (P < 0.05) in tenderness and had a lower (P < 0.05) shear force than those from Control fed animals. It is concluded that feeding microalgae at high levels can beneficially improve the health attributes of beef with only a few effects on sensory quality.     

Hormone-sensitive lipase protein expression and extent of phosphorylation in subcutaneous and retroperitoneal adipose tissues in the periparturient dairy cow

Lipomobilization is essential for dairy cows to balance the energy requirement for milk production in early lactation. This study aimed to determine the role of hormone-sensitive lipase (HSL) and its activation by phosphorylation at Ser 660 (HSLp660) and 563 (HSLp563) in different adipose tissue depots as influenced by time and postpartum diet in dairy cows. Biopsy samples were obtained from s.c. (SCAT) and retroperitoneal (RPAT) adipose tissues of 20 Holstein cows 21 d prepartum, and 1 and 21 d postpartum. After d 1 postpartum, cows were randomly assigned to 2 groups (n = 10). Groups received diets with either a concentrate-to-roughage ratio on a dry matter basis of 30:70% (low-concentrate, LC, group) or 60:40% (high-concentrate group), fed until the third biopsy sampling 21 d postpartum. Dry matter intake, milk yield, and milk composition were recorded. Blood samples were taken weekly, starting 21 d prepartum and analyzed for nonesterified fatty acids, β-hydroxybutyrate (BHBA), glucose, and insulin. Protein expression of HSL and its extent of phosphorylation in adipose tissue were measured by semiquantitative Western blotting. Total HSL expression was lower in both adipose tissues 1 d after calving compared with prepartum sampling (SCAT: 4.10 ± 0.5 vs. 2.4 ± 0.3; RPAT: 11.1 ± 1.3 vs. 6.6 ± 1.1). Phosphorylation at Ser 660 was higher 21 d postpartum compared with 21 d prepartum in RPAT (2.9 ± 0.3 vs. 4.6 ± 0.6). Phosphorylation at Ser 563 was higher 21 d postpartum than 21 d prepartum in SCAT (0.6 ± 0.1 vs. 3.9 ± 1.1), and in RPAT a difference was observed between 21 d prepartum and 1 d postpartum (1.0 ± 0.1 vs. 3.3. ± 0.6). On d 21 postpartum, the LC group showed a lower extent of Ser 563 phosphorylation in RPAT (3.9 ± 0.8 vs.10.0 ± 1.9) and a higher concentration of serum BHBA (0.77 ± 0.05 vs. 0.47 ± 0.11) than did the high-concentrate group. An inhibitory influence of higher BHBA concentrations on HSL phosphorylation in the LC group could be a possible explanation. On comparing RPAT to SCAT, HSL expression and the extent of Ser 660 and 563 phosphorylation was higher in RPAT at 21 d prepartum (HSL: 4.1 ± 0.5 vs. 11.1 ± 1.2; HSLp660 1.3 ± 0.2 vs. 2.9 ± 0.3; HSLp563: 0.6 ± 0.1 vs. 1.0 ± 0.1). In conclusion, the postpartum feeding regimen influenced the phosphorylation pattern, especially in RPAT, implying a regulatory role for different phosphorylation sites in adaptive lipolysis of dairy cows. It is suggested that RPAT is more sensitive to periparturient challenges than is SCAT.     

Agonists of the G protein-coupled receptor 109A-mediated pathway promote antilipolysis by reducing serine residue 563 phosphorylation of hormone-sensitive lipase in bovine adipose tissue explants

A balanced lipolytic regulation in adipose tissues based on fine-tuning of prolipolytic and antilipolytic pathways is of vital importance to maintain the metabolic health in dairy cows. Antilipolytic pathways, such as the G protein-coupled receptor 109A (GPR109A)-mediated pathway and the insulin signaling pathway in bovine adipose tissues may be involved in prohibiting excessive lipomobilization by reducing triglycerol hydrolysis. This study aimed to evaluate the in vitro antilipolytic potential of the mentioned pathways in bovine adipose tissue explants. Therefore, subcutaneous and retroperitoneal adipose tissue samples (approximately 100 mg) of German Holstein cows were treated for 90 min ex vivo with nicotinic acid (2, 8, or 32 μM), nicotinamide (2, 8, or 32 μM), β-hydroxybutyrate (0.2, 1, or 5 mM), or insulin (12 mU/L), with a concurrent lipolytic challenge provoked with 1 μM isoproterenol. Lipolytic and antilipolytic responses of the adipose tissues were assessed by measuring free glycerol and nonesterified fatty acid release. To identify molecular components of the investigated antilipolytic pathways, protein abundance of GPR109A and the extent of hormone-sensitive lipase (HSL) phosphorylation at serine residue 563 were detected by Western blotting. Treatment with nicotinic acid or β-hydroxybutyrate decreased the lipolytic response in adipose tissue explants and concurrently reduced the extent of HSL phosphorylation, but treatment with nicotinamide or insulin did not. Subcutaneous adipose tissue constitutively expressed more GPR109A protein, but no other depot-specific differences were observed. This study provides evidence that the GPR109A-mediated pathway is functionally existent in bovine adipose tissues, and confirms that HSL phosphorylation at serine residue 563 is also important in antilipolytic regulation in vitro. This antilipolytic pathway may be involved in a balanced lipid mobilization in the dairy cow.     

SMYD3-associated pathway is involved in the anti-tumor effects of sulforaphane on gastric carcinoma cells

Food Science and Biotechnology - Sulforaphane (SFN), a natural compound derived from cruciferous vegetables, has been proved to possess potent anti-cancer activity. SMYD3 is a histone...     

Antihyperlipidemic effects of buckwheat leaf and flower in rats fed a high-fat diet

This study was conducted to investigate the hypolipidemic effects of a powdered whole buckwheat leaf and flower mixture in rats fed a high-fat diet. Male Sprague–Dawley rats were divided into three groups: normal control (NC), high-fat (HF), and high-fat supplemented with a mixture of powdered buckwheat leaf and flower (BLF; 5%, wt/wt) groups. The plasma total cholesterol and triglyceride concentrations were significantly lower in the BLF group than in the other groups. Hepatic cholesterol and triglyceride values of the BLF group were similar to those of the NC group. This plant part mixture elevated the faecal triglyceride and acidic sterol level in the BLF group. The result suggest that the beneficial effect of this buckwheat plant portion on plasma and hepatic lipid profiles in high-fat fed rats is partly mediated by higher excretion of faecal lipids and synergistic effect of phenolic compounds and fibre present in the BLF.     

Long-term feeding effects of thermally oxidised oils on the absorption, storage and excretion of fat in rats

 The long term effects of feeding heated and fried vegetable oils namely peanut, sesame and coconut oils, at levels of 5% and 20% for 20 weeks on the absorption, storage and excretion of fat were studied in laboratory rats. Although no significant difference in the absorption rate of heated fats was observed, a marginal increase in the levels of fecal fat excretion was noted in heated/fried oil-fed rats. Deposition of fat in the perirenal adipose tissue indicated higher levels of palmitic and oleic acid in heated/fried oil-fed rats. Received: 14 June 1999 / Revised version: 2 August 1999     

Meta-Review of Protein Network Regulating Obesity Between Validated Obesity Candidate Genes in the White Adipose Tissue of High-Fat Diet-Induced Obese C57BL/6J Mice

Worldwide obesity and related comorbidities are increasing, but identifying new therapeutic targets remains a challenge. A plethora of microarray studies in diet-induced obesity models has provided large datasets of obesity associated genes. In this review, we describe an approach to examine the underlying molecular network regulating obesity, and we discuss interactions between obesity candidate genes. We conducted network analysis on functional protein–protein interactions associated with 25 obesity candidate genes identified in a literature-driven approach based on published microarray studies of diet-induced obesity. The obesity candidate genes were closely associated with lipid metabolism and inflammation. Peroxisome proliferator activated receptor gamma (Pparg) appeared to be a core obesity gene, and obesity candidate genes were highly interconnected, suggesting a coordinately regulated molecular network in adipose tissue. In conclusion, the current network analysis approach may help elucidate the underlying molecular network regulating obesity and identify anti-obesity targets for therapeutic intervention.     

Identification of cohesive and adhesive effects in the cleaning of food fouling deposits

Cleaning of process plants is costly and time consuming. It is important to understand the removal of fouling deposits. Deposits form by adhesion to the surface and cohesion between elements of the deposit. Cleaning can result from either or both adhesive and cohesive failure. Micromanipulation experiments have measured the adhesive/cohesive strength of deposits in terms of the work required to remove them from the surface. Different food deposits have been studied. Tomato paste, bread dough and egg albumin deposits have a lower adhesive than cohesive strength, whilst others (whey protein) have a lower cohesive than adhesive strength. A range of coated surfaces has been used to study the effect of surface energy on the force required for removal of tomato deposits. Minima are found, as predicted by theory. A simple material model has been developed and used to analyse the results in terms of the work required to remove the deposit per unit surface area and volume.

Industrial relevance

Cleaning is a ubiquitous and poorly understood operation in the food industry. Poor cleaning endangers product safety, lowers run length and generates excess effluent. Better understanding of the processes of cleaning is beneficial both in ensuring food safety and in increasing the manufacturing efficiency of process plant.     

The effects of baobab pulp powder on the micro flora involved in tempe fermentation

Locally prepared tempe that underwent natural fermentation was characterized by the growth of Lactobacillus plantarum, Streptococcus lactis , Bacillus sp., Salmonella sp., Klebsiella sp., Lactococcus lactis , Rhizopus sp. and Staphylococcus sp., while fermentation carried out with the addition of varying levels of baobab pulp powder had mainly lactic acid bacteria (LAB)— Lactobacillus plantarum, Lactobacillus fermentum , Lactobacillus acidophilus and Rhizopus sp. dominating. Increasing concentrations of baobab pulp powder led to an increase in the population of lactic acid bacteria (LAB) from 2.3×10² to 3.3×10⁴ while it reduced the population of inoculated Rhizopus from 10² to only six colonies on malt extract agar (MEA).     

Effect of blending and lipase catalyzed interesterification reaction on the cholesterol lowering properties of palm oil with rice bran oil in rats

The effect of feeding blended and interesterified oils containing palm oil (PO) and rice bran oil (RBO) on serum and liver lipids was evaluated in rats. The PO and RBO were blended to contain saturated, monounsaturated and polyunsaturated fatty acids in the proportion of 1:1.5:1. The blended oil was subjected to transesterification reaction using immobilized lipase, lipozyme IM‐RM. Rats were fed a diet containing blended or interesterified oils for 8 weeks. Rats fed PO showed significantly higher levels of cholesterol in serum and liver as compared to those given RBO, blended oil of PO with RBO or interesterified oil. Rats fed blended oils showed a significant decrease in serum cholesterol by 51% compared to rats fed PO. Feeding interesterified oil to rats resulted in decrease in serum cholesterol by 56% compared to rats fed PO, which was 10% lower compared to that observed in rats given blended oil. The present study indicated that a combination of PO with RBO can significantly lower serum lipids in rats as compared to those given diet containing PO alone.     

Isolation of a gene encoding a G protein α subunit involved in the regulation of cAMP levels in the yeast Kluyveromyces lactis

Using chromosomal DNA from Kluyveromyces lactis as template and oligodeoxynucleotides designed from conserved regions of various G protein alpha subunits we were able to amplify by the polymerase chain reaction two products of approximately 0·5 kb (P-1) and 0·8 kb (P-2). Sequencing showed that these two fragments share high homology with genes coding for the Gα subunits from different sources. Using the P-1 fragment as a probe we screened a genomic library from K. lactis and we cloned a gene (KlGPA2) whose deduced amino acid sequence showed, depending on the exact alignment, 62% similarity and 38% identity with Gpa1p and 76% similarity and 63% identity with Gpa2p, the G protein α subunits from Saccharomyces cerevisiae. KlGPA2 is a single-copy gene and its disruption rendered viable cells with significantly reduced cAMP level, indicating that this Gα subunit may be involved in regulating the adenylyl cyclase activity, rather than participating in the mating pheromone response pathway. KlGpa2p shares some structural similarities with members of the mammalian Gαs family (stimulatory of adenylyl cyclase) including the absence in its N-terminus of a myristoyl-modification sequence. The sequence reported in this paper has been deposited in the GenBank data base (Accession No. L45105).     

Taste-active components in the mantle muscle of the oval squid Sepioteuthis lessoniana and their effects on squid taste

Using a series of omission and addition tests and sensory evaluation of synthetic extracts, the taste-active components of the mantle muscle of the oval squid (Sepioteuthis lessoniana) were determined to be glycine, alanine, proline, glutamate, arginine, adenosine 5′-monophosphate, trimethylamine oxide, glycine betaine, as well as potassium, sodium, and chloride ions. A simplified synthetic extract prepared from these 11 taste-active components was found to almost reproduce the taste of the complete synthetic extract containing 45 components of S. lessoniana muscle. This was also the case for three other squid species; Loligo bleekeri, Loligo edulis, and Todarodes pacificus. When certain components were added to the simplified synthetic extracts of these three squid species – sodium ions and glycine for L. edulis, sodium ions and arginine for L. bleekeri, chloride ions, glycine, and arginine for T. pacificus – the taste of the simplified synthetic extracts approximated the extract from S. lessoniana, which had the most preferred taste.     

The effects of milk removal or four-times-daily milking on mammary expression of genes involved in the insulin-like growth factor-I axis

Frequent milking of dairy cows during early lactation elicits both an immediate increase in milk yield and a partial carryover effect that persists to the end of lactation. We hypothesized that the immediate response would be associated with a local increase in insulin-like growth factor (IGF)-I signaling and a consequent increase in mammary growth. Four multiparous cows were assigned at parturition to unilateral frequent milking [UFM; milking of the left udder half twice daily (2×; 0230 and 1430 h); milking of the right udder half 4 times daily (4×; 0230, 0530, 1430, and 1730 h)]. Mammary biopsies were obtained from both udder halves at 5 d in milk at 0530 h (immediately after 4× glands were milked). Incorporation of [³H]-thymidine into DNA and mammary cell apoptosis were not affected by UFM. Because biopsies were obtained when udder halves were at different postmilking intervals, our results reflected both the acute, transient mammary response to milking and the sustained mammary response to frequent milking treatment. We further hypothesized that the acute, transient response involves mechanisms distinct from those regulating the sustained response to frequent milking. To test that hypothesis, mammary biopsies were obtained from UFM cows (n = 5) at 0500 h, when time postmilking was the same for both udder halves. Mammary cell apoptosis was not affected by UFM. Expression of genes involved in the IGF-I axis was analyzed to identify acute responses associated with milking, per se, versus sustained responses to frequent milking treatment. Removal of milk from 4× glands was associated with an acute increase in expression of IGF binding protein-1, -3, and -4 mRNA in 2× glands, whereas IGF-I expression was increased by frequent milking treatment. These effects, however, were significant only for expression of IGF binding protein-3. Expression of IGF-I receptor did not differ because of milking frequency but was higher in both udder halves immediately postmilking, indicating a systemic effect. We conclude that several genes of the IGF-I axis respond to milking, per se, or frequent milking treatment, via at least 3 distinct patterns. Increased milking frequency does not alter mammary cell proliferation or apoptosis at 5 d in milk; however, it may increase the bioavailability of IGF-I in the mammary gland. Moreover, the increase in local expression of IGF-I in 4× udder halves indicates a role for this gene in the immediate milk yield response to frequent milking during early lactation.