肌肽对猪肉的氧化抑制和保鲜作用

肌肽是一种具有抗氧化等功能的天然的二肽,本试验比较了肌肽对猪肉匀浆的抗氧化作用,同时比较了不同保鲜剂对冷鲜肉保藏期的延长作用。实验发现,1mmol/L肌肽标准液对猪肉匀浆中丙二醛的形成量就能起到显著的抑制作用(P<0.05),此时对体系中脂类氧化的抑制率即达到12%,5mmol/L肌肽对体系中脂类氧化的抑制率达15%,20mmol/L肌肽对体系中脂类氧化的抑制率达47%,表明不同浓度的肌肽均能对猪肉匀浆中脂类氧化起显著的抑制作用,其中随浓度的增加效果增强。与BHT和α-生育酚相比,肌肽对TBARS的抑制能力较高。肌肽可以延长冷鲜肉的保存时间,添加了肌肽的冷鲜肉保藏时间由不添加保鲜剂的9天增加到15天,其效果要优于抗坏血酸,肌肽牛肉预煮液也可以延长冷鲜肉的贮藏时间。     

Antioxidant activity of mechanically separated pork extracts

Utilization of synthetic carnosine as a food additive is limited by both regulatory and economic hurdles. Therefore, the potential of producing carnosine-containing antioxidant extracts from an underutilized skeletal muscle source, mechanically separated pork (MSP), was investigated. Carnosine-containing MSP extracts were capable of inhibiting lipid oxidation both in vitro and in salted ground pork. Heating (60-80°C) the MSP extract removed iron and increased in vitro antioxidant activity. Isolation of a low molecular weight fraction of the MSP extract by ultrafiltration was effective at decreasing iron but did not substantially increase in vitro antioxidant activity. Freeze dried extracts (untreated, 80°C, ultrafiltration permeate) were capable of inhibiting both TBARS and lipid peroxide formation in ground, salted pork stored at -15°C. While MSP extracts were capable of inhibiting lipid oxidation both in vitro and in salted, ground pork, their antioxidant activity was low suggesting that their use as a food additive would be impractical.     

The antioxidative properties of Holy basil and Galangal in cooked ground pork

The ethanolic extracts from Holy basil and Galangal were examined for their extraction yield, total phenolic content, antioxidant activity against a β-carotene-linoleic acid emulsion system, DPPH scavenging activity and reducing power. Ethanolic extracts of Holy basil exhibited higher extraction yield, total phenolic content, antioxidant activity, DPPH scavenging activity and reducing power than ethanolic extracts of Galangal. Antioxidative efficiency to inhibit lipid oxidation of dried Holy basil and dried Galangal powder, ethanolic extracts of Galangal and Holy basil and commercial antioxidant mixture in cooked ground pork was investigated during refrigerated storage at 5°C for 14 days. The quantitative measurements of thiobarbituric acid reactive substances (TBARS), conjugated diene, peroxide value (POV) and hexanal content were used as indicators of lipid oxidation. Increased levels of TBARS value, POV and hexanal content were noticed in all meat samples during storage, however most marked in cooked ground pork without antioxidants, whereas conjugated diene tended to decrease with increasing storage time. Ranking of the treatment in order of their antioxidant effectiveness showed that commercial antioxidant mixture (0.3% citric acid+0.5% ascorbic acid+0.02% α-tocopherol)>dried Galangal powder>dried Holy basil powder>ethanolic extracts of Galangal>ethanolic extracts of Holy basil>control. Furthermore, in cooked ground pork samples a high correlation between TBARS value and hexanal contents was obtained.     

Inhibition of Oxidative Rancidity in Salted Ground Pork by Carnosine

Carnosine (0.5 and 1.5%) effectively inhibited formation of lipid peroxides and thiobarbituric acid reactive substances (TBARS) in frozen (? 15°C) salted ground pork during up to 6 mo storage. Inhibition of TBARS formation by carnosine (1.5%) was better than sodium tri-polyphosphate (0.5%), ot-tocopherol and butylated hydroxytoluene (0.02% of fat content). Carnosine was the most effective at preventing oxidative rancidity and color changes as determined by sensory panel, in salted ground pork after 1 mo frozen storage (?15°C). These data suggested that carnosine could be used as a “natural” antioxidant in muscle foods.     

Effect of antioxidants on stabilization of meat products fortified with n-3 fatty acids

The effects of an n-3 oil emulsion, with and without added antioxidants, on lipid oxidation in n-3 polyunsaturated fatty acid (PUFA)-fortified meat products were studied. An emulsion of n-3 PUFAs was prepared (25% algal oil, 2.5% whey protein isolates, 10mM sodium citrate, 0.2% potassium sorbate, 500ppm of 70% mixed tocopherols, 100μM EDTA, pH 3, pasteurized at 75°C for 30min) and incorporated into fresh ground turkey, and fresh pork sausage (20% fat) to achieve a concentration of 500mg n-3 PUFA/110g meat. An antioxidant combination containing rosemary (0.2% w/w; radical quencher), citrate (0.5% w/w; sequestrant) and erythorbate (1g/kg product; reductant) was prepared and incorporated into ground turkey patties (5cm dia, 1.5cm thick) or fresh pork sausages (5cm dia, 1.5cm thick). Meat products were stored at 4°C or -18°C and analyzed for color (L*, a*, b* values), lipid oxidation (TBARS and lipid hydroperoxides) and n-3 PUFA profile. a* Values of refrigerated ground turkey patties decreased with storage, and an antioxidant combination effect was observed after 4 days (P<0.05). For fresh pork sausages at 4°C, control+antioxidant (CON+ANTI), and n-3+antioxidant (n-3+ANTI) groups showed greater a* values than controls (CON) indicating that the antioxidant combination stabilized meat color. TBARS and lipid hydroperoxides of both n-3 PUFA-enhanced meat products increased with storage (P<0.05); there were no significant changes in TBARS or lipid hydroperoxides for treatments containing the antioxidant combination (P<0.05). The actual level of n-3 PUFA incorporation in both meat products was greater than 87%; n-3 PUFA concentrations did not change within any treatment during storage (P>0.05). These results provide support for including antioxidant protection in n-3 PUFA fortified meat products.     

Interactions Between Carnosine and the Different Redox States of Myoglobin

To better understand the mechanism by which camosine inhibits myoglobin oxidation in salted ground pork, interactions of camosine with ferrylmyoglobin (ferMb), metmyoglobin (metMb) and oxymyoglobin (oxyMb) were investigated. Camosine (0–50 mM pH 5.0–7.5) accelerated the conversion of metMb to oxyMb at pH ≥ 7.0 and carnosine concentrations ≥ 25 mM. Camosine (1–50 mM) also accelerated the conversion of oxyMb to metMh with its formation rates increasing with decreasing pH and increasing camosine concentrations. Camosine (1–25 mM) inhibited ferMb-catalyzed oxidation of phosphatidylcholine liposomes 16–76% and reduced the ferMh electron paramagnetic resonance signal 24–43%. Results suggested that the color stabilizing effects of camosine were related to its antioxidant activity.     

Effect of phosvitin on lipid and protein oxidation in ground beef treated with high hydrostatic pressure

In this study, we aimed to examine the effect of phosvitin on lipid and protein oxidation of raw and cooked ground beef treated with high hydrostatic pressure (HHP). Ground beef patty with 0, 500, or 1000 mg phosvitin/kg meat was treated with HHP at 0.1, 300, or 600 MPa. Half of the patties were used in a raw meat analysis, and the other half were used in a cooked meat analysis. Phosvitin and HHP treatment at 300 MPa synergistically reduced microbial growth, and HHP treatment at 600 MPa reduced microbial counts to undetectable levels (< 1 log CFU/g) throughout the length of the study in all samples. Phosvitin delayed lipid and protein oxidation in HHP-treated cooked and raw ground beef, respectively. However, phosvitin had no effect on the color changes of raw ground beef attributable to HHP. The results indicated that phosvitin could enhance the stability of lipids and proteins but not color changes of raw ground beef caused by HHP.     

Effects of high‐pressure processing and enzymatic dephosphorylation on phosvitin properties

BACKGROUND: Egg phosvitin could be a good source of functional peptides. Enzymatic dephosphorylation and high‐pressure processing combined with thermal treatment applied before proteolysis could produce phosvitin hydrolysates with different properties compared to its native form. RESULTS: Phosvitin structure was maintained overall during high‐pressure treatment of 600 MPa applied at an initial temperature of 65 °C regardless of the pH and duration of treatment, confirming the high structural stability of this phosphoprotein. Treatment of phosvitin with phosphatase increased the degree of dephosphorylation from 24% to 63%, after 2 and 18 h, respectively. Moderate dephosphorylation of phosvitin prior to proteolytic digestion improved its hydrolysis, allowing formation of peptides with a molecular weight lower than 17,000 kDa as determined by size exclusion chromatography. Angiotensin‐converting enzyme (ACE) inhibition and antioxidant activity of dephosphorylated and protease‐treated phosvitin was increased by 52% and 39%, respectively, as compared to protease‐digested native phosvitin. CONCLUSION: Enzymatic dephosphorylation before proteolysis mimicking in vivo gut conditions improved ACE inhibition and antioxidant activity of phosvitin hydrolysates. Copyright © 2012 Society of Chemical Industry     

Antioxidant activity of carnosine in cooked ground pork

Carnosine (0·5-1·5%) reduced (P < 0·05) the formation of thiobarbituric acid reactive substances (TBARS) in cooked unsalted ground pork after 7 days of storage at 4°C. The antioxidant activity of carnosine was less in cooked salted ground pork, with only 1·5% carnosine inhibiting (P < 0·05) TBARS formation during refrigerated storage. The antioxidant activity of carnosine in cooked salted and unsalted ground pork was greater than those of the lipid-soluble free radical scavengers, butylated hydroxytoluene and α-tocopherol (P < 0·05) but less than that of sodium tripolyphosphate (P < 0·05). These data suggest that carnosine could be used to reduce the oxidative deterioration of cooked salted and unsalted ground pork.     

含迷迭香的蛋白基薄膜对高氧气调包装生鲜猪肉的护色及抗氧化作用

以不同质量浓度迷迭香与大豆分离蛋白复合制备活性蛋白膜,并将该蛋白膜用于高氧气调下生鲜猪肉的护色保鲜。分析猪肉贮藏期间CIE a*值、正铁肌红蛋白、硫代巴比妥酸反应（thiobarbituric acid reactive substances,TBARS）值、蛋白质羰基及肉品硬度的变化情况。结果表明：肉样表面喷洒0.05 g/100 mL迷迭香提取物有效抑制了高氧气调包装肉品的脂类氧化和贮藏后期的颜色劣变。而蛋白膜加入不同质量浓度迷迭香对高氧气调包装的猪肉表现出不同的抗氧化活性。纯蛋白膜和0.025 g/100 mL迷迭香包装组对猪肉没有表现出护色作用,但对猪肉贮藏期间脂类和蛋白质的氧化起到了一定的抑制作用;0.1、0.2 g/100 mL迷迭香包装组有效延缓了猪肉a*值的下降和正铁肌红蛋白、TBARS值的生成,且其对猪肉的护色效果好于迷迭香直接喷洒处理,但无法抑制蛋白质羰基的形成。而0.05 g/100 mL迷迭香包装组在整个贮藏期间对猪肉颜色、脂类、蛋白质等的抗氧化效果均好于迷迭香直接喷洒处理,且基本维持了肉品贮藏期间的硬度,这表明蛋白膜对迷迭香的包埋显著提高了迷迭香对高氧气调下猪肉的抗氧化活性。     

STABILIZATION OF MEAT LIPIDS WITH GROUND SPICES

The antioxidant efficacy of ground clove, ginger, oregano, rosemary, sage, and thyme was investigated in comminuted pork systems. Spices at 200–2000 ppm levels of addition inhibited the formation of the 2-thiobarbituric acid (TBA) reactive substances (TBARS) by 12–96% over 21-days of storage at 4C. The anti-oxidative effect of spices was concentration-dependent; but close followed by sage and then rosemary was most effective. Ginger and thyme exerted the least effect in prevention of oxidation of meat lipids.     

Comparative Studies on the α and α-Phosvitin from Hen's Egg Yolk

Physico-chemical properties of α and β-phosvitin were compared. Considerable difference was observed in amino acid composition. Higher concentrations of carbohydrates were found in the β-component than in α. The α-phosvitin was more precipitable with lo-15 mM Ca ion than β. Phosvitin was so heat resistant that no change was observed on electropherogram by heating below 100°C for 10 min, and no coagulation occurred up to 140°C. About 12% of the phosphorus was liberated from whole phosvitin by heating at 140°C for 10 min. All preparations of phosvitin isolated from six individual eggs and mixed yolk of 57 eggs contained the two components.     

Antioxidative effect of added dried Holy basil and its ethanolic extracts on susceptibility of cooked ground pork to lipid oxidation

Efficacy of varying concentrations of dried Holy basil powder and its ethanolic extracts in retarding oxidative rancidity was tested with cooked ground pork. The development of lipid oxidation products during 14 days refrigerated storage (5 °C) was evaluated by means of thiobarbituric acid-reactive substances (TBARS) value, peroxide value (POV), conjugated diene and hexanal content. In the amounts studied, dried Holy basil powder and its ethanolic extract significantly (P < 0.05) inhibited the formation of TBARS, peroxide, conjugated dienes and hexanal in a dose-dependent manner. The oxidation process was significantly (P < 0.05) influenced by the type of antioxidant and its concentration. Addition of dried Holy basil powder to cooked ground pork was more effective in inhibiting lipid oxidation than its ethanolic extracts. Additionally, TBARS values and hexanal contents in cooked ground pork were highly correlated (r² = 0.95; P < 0.05) with each other.     

Species-Specific Effects of Sarcoplasmic Extracts on Lipid Oxidation in vitro

ABSTRACT:  The degree to which lipid and myoglobin (Mb) oxidation processes interact in meat can be species-specific. We investigated the effects of beef and pork sarcoplasmic extracts containing different Mb concentrations on lipid oxidation in a liposome system. Sarcoplasm was extracted from beef and pork longissimus dorsi and psoas major muscles. Beef sarcoplasm was diluted with 0.1 M phosphate buffer to obtain a Mb concentration equivalent to that in pork sarcoplasm. Conversely, equine heart Mb was added to pork sarcoplasm to match the myoglobin concentration of beef sarcoplasm. This resulted in beef and pork sarcoplasms, each with 2 different Mb concentrations for the longissimus (0.02 mM and 0.07 mM) and psoas (0.05 and 0.12 mM). Sarcoplasm (or phosphate buffer control) was incorporated within a phosphatidylcholine liposome preparation and incubated at 25°C. Thiobarbituric acid reactive substances (TBARS) were measured at 0, 30, 60, 90, and 120 min of incubation. Regardless of species, greater Mb concentration within the sarcoplasm increased lipid oxidation ( P < 0.05). Across muscles, pork sarcoplasm had lower TBARS values than beef sarcoplasm ( P < 0.05). Our results suggest that pork sarcoplasm has a lesser effect on lipid oxidation than beef sarcoplasm for a common Mb concentration. However, increased myoglobin concentration within sarcoplasm promotes lipid oxidation regardless of species.     

Culinary herbs inhibit lipid oxidation in raw and cooked minced meat patties during storage

The effect of dried spices and the ethanol extract of those spices was studied on the stability of fresh chicken minced meat, and fresh and cooked pork patties pretreated with NaCl during refrigerated and frozen storage. The antioxidant activities of the spices were measured by thiobarbituric acid reactive substances (TBARS) and peroxide value (POV) in meat samples. The lipid oxidation was effectively inhibited in the chicken meat treated with several dry spices diminishing the TBARS to a range of 32% and 83% of those found in the control samples in frozen stored meat for 6 months. Marjoram, wild marjoram and caraway were the most effective dry spices. Ethanolic extracts of the same spices were more potent as antioxidants by lowering the concentration of the TBARS to a range of 20–27% of those found in the control samples. Addition of sodium salt to the minced pork resulted very high concentrations of the oxidation products originated from the polyunsaturated fatty acids. The treatment with ethanolic extract of spices (sage, basil, thyme and ginger) significantly inhibited the lipid peroxidation in refrigerated and chilled pork patties pretreated with NaCl by reducing both POV and TBARS. Heat treatment with microwaves produced significantly elevated levels of both lipid peroxides and TBARS, but the amount of these oxidation products was less than 10% in spice‐treated salted meat samples compared to that in untreated ones. Lipid peroxidation also grew continuously during the storage period at −18°C in raw and cooked samples. Ethanolic extracts of spices had a very strong antioxidative effect inhibiting lipid peroxidation in heat‐treated meat products during frozen storage. The highest antioxidant activity was observed in the case of ginger. High correlation coefficients were found between TBARS and POV both in raw and cooked pork patties (0.86, 0.91, respectively) during frozen storage. It is supposed that these compounds originated from the polyunsaturated fatty acids during oxidation processes but at different stages. Utilization of spices, spice mixtures or spice extracts in semi‐prepared meat products intended to be frozen for up to 6 months or more before consumption is proved to be advantageous in regard of shelf life of the food, as well as of human health, because of the beneficial effect of spices in inhibition of lipid peroxidation during heat treatment and chilling storage. © 1999 Society of Chemical Industry     

Egg yolk phosvitin and functional phosphopeptides--review

Phosphopeptides are among the most interesting biomolecules with characteristic molecular structure and functions. They usually contain clusters of phosphoserines, which can effectively bind calcium and iron, and inhibit formation of insoluble calcium phosphates or iron complexes. Therefore, phosphopeptides can increase calcium or iron bioavailability and prevent lipid oxidation in foods. Milk protein casein has been currently used by industry to produce phosphopeptides. Egg yolk phosvitin is considered as the most phosphorylated protein found in the nature. Phosvitin from egg yolk can be much better source for producing phosphopeptides with varying sizes and functions than casein because it contains much greater number of phosphates in the molecule than casein. However, still phosvitin has not been subjected to considerable attention with regard to bioactive peptides production.     

Inhibition of Lipid Oxidation and Rancidity in Precooked Pork Patties by Radical‐Scavenging Licorice (Glycyrrhiza glabra) Extract

This study investigated the efficacy of licorice extract (LE) to curtail lipid oxidation and protect sensory attributes of ground pork during refrigerated and frozen storage. Pork patties (20% fat) were formulated with 0%, 0.02%, 0.05%, and 0.1% (meat basis) LE or rosemary extract (RE) as comparison or 0.01% (fat basis) BHA with 0 or 1.5% NaCl. Raw and precooked (75 °C) patties were packaged in polyvinylchloride overwrapped trays and stored at 2 °C up to 7 and 14 d, respectively, or at –20 °C up to 6 mo. Lipid oxidation (thiobarbituric acid‐reactive substances [TBARS]) and sensory attributes of stored patty samples were evaluated, radical scavenging activity of the LE was measured, and the active phenolic compounds were identified. Cooking yield (<85%) was similar among antioxidant treatments, and lipid oxidation was minimal in refrigerated or frozen raw samples. However, TBARS values in refrigerated precooked control patties (0.22 mg/kg) rose to 9.3 to 9.4 mg/kg after 14 d, compared to 3.4 to 4.4 and 4.4 to 6.9 mg/kg in patties treated with 0.1% LE and RE, respectively. In frozen precooked samples, TBARS (0.22 mg/kg) increased to 1.3 mg/kg (P < 0.05) in control patties after 6 mo and had no significant change in patties treated with 0.1% LE or 0.01% butylated hydroxyanisol. Sensory panel evaluation confirmed strong inhibition of rancidity production by LE, corroborating its remarkable antiradical activity due to the presence of multiple phenolics. The results indicate that licorice has great potential as a natural antioxidative additive to extend the shelf‐life of precooked pork.     

Comparison of solvent and microwave extracts of cranberry press cake on the inhibition of lipid oxidation in mechanically separated turkey

Cranberry press cake, an under utilized by-product of the cranberry processing industry is a potential source of food antioxidants. The objective of this research were (1) to prepare extracts from cranberry press cake using solvent extraction (SE) and microwave assisted solvent extraction (MASE), and (2) to test the ability of these extracts to inhibit lipid oxidation in mechanically separated turkey (MST). Water, ethanol and acetone were used as extraction solvents. Heating press cake prior to extraction with 70% ethanol increased antioxidant efficacy compared to extracting unheated press cake. Water extracts were least effective in inhibiting lipid oxidation. The most effective extracts were obtained by SE with 100% acetone or MASE with 100% ethanol. A poor correlation of 0.69 was obtained between the total phenols in the extracts and their ability to inhibit thiobarbituric acid reactive substances (TBARS) formation in MST. The correlation coefficient between the amount of quercetin in the extracts and the number of days of TBARS inhibition in MST was 0.87. This indicates that although quercetin may be good inhibitor of lipid oxidation, polyphenols other than quercetin are likely have a role in the inhibition of TBARS in MST. For a similar yield of the extracts, MASE extract using 100% ethanol was a better inhibitor than 100% ethanol SE extract of lipid oxidation in MST. In terms of choice of solvent, based on their flammability and toxicity, MASE with 100% ethanol would be a more likely a choice over SE with 100% acetone, for inhibiting oxidation in MST.     

花椒提取物对调理猪肉饼冷藏期间品质的影响研究

探究不同添加量的花椒提取物对调理猪肉饼冷藏期间品质及氧化程度的影响。将0.01%、0.02%和0.03%的花椒提取物添加到调理猪肉饼中,研究其在1、4、7、10 d冷藏期间的pH、颜色、质构、硫代巴比妥酸值(thiobarbituric acid reactive substance,TBARS)和巯基值的变化,并与0.02%二丁基羟基甲苯(butylated hydroxytoluene,BHT)作比较。研究结果表明,添加花椒提取物对调理猪肉饼冷藏期间的pH、颜色无显著影响(p>0.05),在一定程度上降低了其硬度和咀嚼性。此外,添加花椒提取物可显著降低猪肉饼脂肪氧化和蛋白质氧化程度(p<0.05)。当添加量为0.01%和0.02%时,花椒提取物处理组抑制脂肪氧化的效果与0.02%的BHT效果相当,而当添加量增加至0.03%时,花椒提取物组抗脂肪氧化效果优于0.02%的BHT,且其蛋白氧化程度在整个冷藏期间均显著低于对照组(p<0.05),表明花椒提取物可有效抑制猪肉饼中脂肪和蛋白质氧化,其中0.03%花椒提取物组效果最好,甚至优于0.02%的BHT。