Chloride salt type/ionic strength, muscle site and refrigeration effects on antioxidant enzymes and lipid oxidation in pork

The effects of NaCl and KCl at varying ionic strengths on catalase and glutathione peroxidase (GSH-Px) activities and lipid oxidation in refrigerated ground pork muscles from different anatomical locations were studied. Catalase and GSH-Px activities were higher in boston butt (BB) than in longissimus dorsi (LD), whereas lipid oxidation measured by 2-thiobarbituric acid substances (TBARS) content was higher in LD. Catalase activity was stable in both BB and LD during 4-day storage; GSH-Px activity decreased in LD. GSH-Px activity decreased more with NaCl than KCl, whereas salt type had no consistent effect on catalase activity. TBARS content, however, increased more with NaCl than with KCl. NaCl at the highest ionic strength decreased GSH-Px activity by 19.2 and 18% in LD and BB, respectively, and increased TBARS content by 8- and 3.6-fold. Results indicated that pork samples with higher catalase and GSH-Px activities would undergo less lipid oxidation, and the accelerated lipid oxidation in salted pork may be partly related to a decrease in GSH-Px activity.     

Effect of gamma irradiation on microbial load and quality characteristics of minced camel meat

The effect of gamma irradiation on microbial load, chemical and sensory characteristics of camel meat has been evaluated. Camel meat was irradiated at doses of 0, 2, 4 and 6 kGy of gamma irradiation. Irradiated and non-irradiated meat was kept in a refrigerator (1–4 °C). General composition and sensory evaluation of camel meat was done two days after irradiation, whereas, microbiological and chemical analysis was done immediately after irradiation and throughout the storage periods. The results indicated that all doses of gamma irradiation reduced the total mesophilic aerobic plate counts (TPCs) and total coliforms of camel meat. Thus, the microbiological shelf-life of camel meat was significantly extended from less than 2 weeks (control) to more than 6 weeks (samples irradiated with 2, 4 or 6 kGy). No significant differences in moisture, protein, fat, thiobarbituric acid (TBA) values, total acidity and fatty acids of camel meat were observed due to irradiation. There were slight effects of gamma irradiation in both total volatile basic nitrogen (VBN) and lipid oxidation values in camel meat. Sensory evaluation showed no significant differences between irradiated and non-irradiated camel meats.     

Antioxidant activity of Carob fruit extracts in cooked pork meat systems during chilled and frozen storage

The purpose of this study was to evaluate the effect of adding condensed tannins in the form of non-purified (Liposterine^®) or purified (Exxenterol^®) extracts obtained from Carob fruit to prevent lipid cooked pork meat systems from oxidising during chilling and frozen storage. The antioxidant activity of these extracts was compared with that of α-tocopherol. Meat lipid alteration was evaluated as thiobarbituric acid reactive substances content (TBARS) and polar material-related triglyceride compounds followed by high-performance size-exclusion chromatography (HPSEC). TBARS levels were lower (P < 0.05) in samples containing Liposterine (LM), Exxenterol (EM), and α-tocopherol (TM) than in control sample (CM) under chilled storage. TBARS formation was similar (P > 0.05) for LM and EM but lower (P < 0.05) than for TM. Polar material increased several times in all samples, but significantly less in TM and EM than in LM. Thermal oxidation compounds determined by HPSEC were lower (P < 0.05) in EM than in LM or TM. The changes in polar material were proportionally smaller after six months frozen storage than after chilled storage, with Exxenterol displaying the highest antioxidant protection. Therefore Carob fruit extracts can be successfully used to reduce fat alteration in cooked pork meat at chilled and frozen temperatures.     

Antioxidant potential of mint (Mentha spicata L.) in radiation-processed lamb meat

The effectiveness of mint leaves, a common herb used in Indian cuisine, as a natural antioxidant for radiation-processed lamb meat was investigated. Mint extract (ME) had good total phenolic and flavonoid contents. It exhibited excellent antioxidant activity, as measured by β-carotene bleaching and 1,1-diphenyl-2-picrylhydrazyl (DPPH) assays. It also showed a high superoxide- and hydroxyl-scavenging activity but low iron-chelating ability. A positive correlation was found between the reducing power and the antioxidant activity. The antioxidant activity of ME was found to be comparable to the synthetic antioxidant, butylated hydroxytoluene (BHT). The suitability of ME as an antioxidant was determined during radiation processing of lamb meat. ME retarded lipid oxidation, monitored as thiobarbituric acid-reactive substances (TBARS), in radiation-processed lamb meat. TBARS values of ME containing irradiated meat stored at chilled temperatures were significantly lower (p < 0.05) than samples without ME. After 4 weeks of chilled storage, TBARS in irradiated meat containing ME (0.1%) was half of that in untreated irradiated meat.     

Anti-oxidant effect of extracts of kinnow rind,pomegranate rind and seed powders in cooked goat meat patties

To overcome the disadvantages of using synthetic anti-oxidants in meat products, an investigation was carried out to evaluate the anti-oxidant effect of extracts of fruit by-products viz., kinnow rind powder (KRP), pomegranate rind powder (PRP) and pomegranate seed powder (PSP) in goat meat patties. Total phenolics content, DPPH radical scavenging activity and effect of these extracts on instrumental color, sensory attributes and TBARS values during storage (4 ± 1 °C) of goat meat patties were evaluated. Results showed that these extracts are rich sources of phenolic compounds having free radical scavenging activity. Hunter Lab L value significantly (P < 0.05) lowered in PRP followed by PSP and KRP patties. Sensory evaluation indicated no significant differences among patties. Further, a significant (P < 0.5) reduction in TBARS values (lipid oxidation) during storage of goat meat patties was observed in PRP, PSP and KRP as compared to control patties. Average TBARS values (mg/kg meat) during refrigerated storage (4 ± 1 °C) were significantly lower in PRP, followed by PSP and KRP as compared to control. The overall anti-oxidant effect was in the order of PRP > PSP > KRP. It was concluded that extracts of above fruits by-product powders have potential to be used as natural anti-oxidants in meat products.     

Effects of temperature and NaCl percentage on lipid oxidation in pork muscle and exploration of the controlling method using response surface methodology (RSM)

This study investigated the effects of temperature (15, 20, 25, 30 or 35 °C) and sodium chloride (NaCl) (0.5%, 1.0%, 2.0%, 3.0% or 4.0%) on lipid oxidation by measuring the peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) in minced pork muscle. Both temperature and NaCl showed significant (P < 0.05) pro-oxidant effect within studied range. The activation energy (92.35 kJ/mol) for PV was higher than that (65.66 kJ/mol) for TBARS, indicating that lipid primary oxidation was more affected by temperature than the secondary oxidation. Temperature and NaCl had extremely significant (P < 0.001) interaction for lipid oxidation. Elevating temperature could significantly (P < 0.05) decrease the threshold value of NaCl concentration affecting lipid oxidation in the minced pork muscle. Based on the results, a relatively high temperature and a moderate or slightly lower level of NaCl, are recommended conditions for the fastest lipid primary oxidation rate in pork muscle.     

Antioxidant activity of hydroxytyrosol in frankfurters enriched with n-3 polyunsaturated fatty acids

The capacity of hydroxytyrosol (HXT) to inhibit lipid oxidation in cooked pork meat batter, oil-in-water emulsions and potential functional frankfurters formulated with a healthier oil combination (as animal fat replacer) was studied during chilling storage, and its effect compared with those produced by synthetic antioxidants (BHA/BHT). Although efficiency varied, HXT was an effective antioxidant during chilling storage in the three food matrices studied. In general the order of inhibition capacity of HXT against lipid oxidation (thiobarbituric acid-reactive substances-TBARS) was cooked meat batter > oil-in-water emulsion > frankfurters, whereas in the case of BHA/BHT (with lower inhibitory activity than HXT) it was cooked meat batter > oil-in-water emulsion, and there was no antioxidative effect in frankfurters. Whereas significant correlations were established between lipid oxidation (TBARS) and antioxidative capacity measured by photochemiluminescence (PCL) in frankfurters supplemented with HXT and BHA/BHT, no significant correlations were found between ferric reducing/antioxidant power assay (FRAP) and TBARS and PCL.     

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     

Evaluation of the antioxidant activities and nutritional properties of ten edible plant extracts and their application to fresh ground beef

In this study, we assessed the antioxidant efficacy and nutritional value of 10 leafy edible plants and evaluated their potential as natural antioxidants for meat preservation. We measured total phenolic content, 2,2-diphenyl-1-picryl-hydrazil (DPPH) radical scavenging activity, and vitamin C, chlorophyll, and carotenoid contents of 70% ethanol and water extracts of the edible plants. Based on these results, we investigated the effects of butterbur and broccoli extracts on lipid oxidation in ground beef patties. Plant extracts and butylated hydroxytoluene (BHT) were individually added to patties at both 0.1% and 0.5% (w/w) concentrations. Thiobarbituric acid reactive substance (TBARS) values and color parameters were tested periodically during 12 days of refrigerated storage. TBARS levels were significantly lower (p ≤ 0.05) in the samples containing plant extracts or BHT than the non-treated control. In addition, the beef patties formulated with the selected plant extracts showed significantly (p ≤ 0.05) better color stability than those without antioxidants. These results indicate that edible plant extracts are promising sources of natural antioxidants and can potentially be used as functional preservatives in meat products.     

Effects of calf diet, antioxidants, packaging type and storage time on beef steak storage

The effect of basal dietary supplemented with vegetable oils plus vitamin E (sunflower, soybean, linseed and a basal diet control), type of packaging (MAP or vacuum), addition of natural antioxidant (grape seed, rosemary) and storage time (0, 7, 14 and 21 days) on lipid oxidation, color stability, vitamin E content, and total aerobic bacterial counts in steaks of Longissimus thoracis was studied. The triple interaction diet × time × packaging affected oxidative stability, redness and yellowness of the meat. TBARS values did not increase with time in vacuum-packaged samples for all dietary treatments. However, samples from MAP and control showed the highest TBARS values after 21 days of storage (0.72 mg MDA/kg of meat, P < 0.05). Both exogenous antioxidant extracts and MAP maintained low total aerobic counts in steaks until the 21st day. Calves should be fed a diet supplemented with L-VE, stored in MAP and treated with grape seed extract to extend the shelf life of their meat.     

Antioxidative effect of dietary grape pomace concentrate on lipid oxidation of chilled and long-term frozen stored chicken patties

Grape pomace concentrate (GPC) is a natural source of phenolic compounds with high antioxidant capacity. The effect of a diet containing GPC on lipid peroxidation levels (TBARS) and antioxidant capacity (ABTS method) of raw and cooked chicken breast meat patties stored in chilled conditions (4 °C) for 0, 3, 6, 13 and 20 days, and long-term frozen storage (6 months) was investigated. Chickens were fed GPC at levels of 0, 30 and 60 mg/kg from 3 to 6 weeks of age. Dietary GPC did not affect chicken performance. Lipid oxidation (TBARS value) was significantly increased by the storage time (0–20 days and 6 months of storage, respectively) in raw and cooked samples. Dietary GPC significantly caused an inhibitory effect on lipid oxidation of raw and cooked breast chicken patties compared with samples obtained from birds fed the control diet at 20 days and long-term frozen storage (6 months). Radical scavenging capacity was significantly increased at 20 days in cooked samples and significantly reduced at 6 months of storage in raw and cooked samples. The higher concentration of dietary GPC increased the ABTS values only in the raw samples. These results indicated that dietary grape pomace concentrate could be effective in inhibiting lipid oxidation of chilled and long-term frozen stored chicken patties.     

Effect of salt,kinnow and pomegranate fruit by-product powders on color and oxidative stability of raw ground goat meat during refrigerated storage

Effects of salt, kinnow and pomegranate fruit by-product powders on color and oxidative stability of raw ground goat meat stored at 4 ± 1 °C was evaluated. Five treatments evaluated include: control (only meat), MS (meat + 2% salt), KRP (meat + 2% salt + 2% kinnow rind powder), PRP (meat + 2% salt + 2% pomegranate rind powder) and PSP (meat + 2% salt + 2% pomegranate seed powder). Addition of salt resulted in reduction of redness scores. Lightness increased in control and unchanged in others during storage. Redness scores declined and yellowness showed inconsistent changes during storage. Thiobarbituric acid reactive substances (TBARS) values were higher (P < 0.05) in MS followed by control and KRP samples compared to PRP and PSP samples throughout storage. The PSP treated samples showed lowest TBARS values than others. Percent reduction of TBARS values was highest in PSP (443%) followed by PRP (227%) and KRP (123%). Salt accelerated the TBARS formation and by-products of kinnow and pomegranate fruits counteracted this effect. The overall antioxidant effect was in the order of PSP > PRP > KRP > control > MS. Therefore, these powders have potential to be used as natural antioxidants to minimize the auto-oxidation and salt induced lipid oxidation in raw ground goat meat.     

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.     

Assessment of the influence of diet on lamb meat oxidation

The effect of pasture- or concentrate-diet on colour stability, lipid oxidation and protein oxidation was measured in lamb meat (M. longissimus dorsi) during refrigerated storage of 7 days under gas permeable film. Lipid and protein oxidation increased rapidly with storage time while evolution of colour parameters exhibited a biphasic curve. Diet had an important effect on lipid oxidation where animals fed concentrate showed higher thiobarbituric reactive substance (TBARS) levels than animals fed pasture-diet. However the nature of diet did not affect protein oxidation or colour parameters of meat. In parallel anti-oxidant status of meat was estimated by measurement of vitamin E content and anti-oxidant enzyme activities while pro-oxidant status was evaluated by haeminic iron, polyunsaturated fatty acid (PUFAs) and glycogen content of muscle. Statistical analysis was performed in order to relate oxidation parameters to pro- and anti-oxidant status of muscle.     

Retardation of myoglobin and haemoglobin-mediated lipid oxidation in washed bighead carp by phenolic compounds

Antioxidative activities of phenolic compounds (caffeic acid, gallic acid and tannic acid; 200 ppm) in washed mince (pH 6), with added myoglobin (Mb) and haemoglobin (Hb), from bighead carp (Hypophthalmichthys nobilis), during 9 days of iced storage, were studied. Tannic acid exhibited the preventive effect on discolouration of washed mince containing Mb or Hb during storage (P < 0.05). High peroxide value (PV) was found and large amount of, thiobarbituric acid-reactive substances (TBARS) and hexanal were formed in washed mince containing haem proteins, especially Hb. As determined by apo Streptococcal haem-associated protein, Hb had the lower haem affinity than Mb. Phenolic compounds, especially caffeic acid and gallic acid, could lower lipid oxidation induced by Mb or Hb throughout storage (P < 0.05). Prevention of haem release, as well as inhibition of lipid oxidation induced by haem proteins with selected phenolic compounds, should be an alternative means in lowering discolouration and lipid oxidation in fish muscle.     

Influence of sodium chloride on antioxidant enzyme activity and lipid oxidation in frozen ground pork

Ground pork containing 0–2.0% NaCl was stored at −15 °C for 10 weeks. During storage both thiobarbituric acid reactive substances (TBARS) and lipid peroxides increased with increasing NaCl concentrations. The activity of catalase (CAT), glutathione peroxidase (GSH-Px) and Superoxide dismutase (SOD) decreased 8, 32 and 27%, respectively, after 10 weeks of storage. CAT and SOD activity decreased primarily during the first week while GSH-Px activity decreased for up to 4 weeks. To determine if NaCl influenced enzyme inactivation rates, the activity of the antioxidant enzymes from stored, salted (0.5–2.0%) ground pork were determined at equal ionic strengths. Under these conditions, NaCl was not observed to accelerate CAT, SOD and GSH-Px inactivation in ground muscle during storage. However, altering ionic strength (0.5–2.0% NaCl) in the enzymes assays decreased the activity of muscle-extracted CAT, SOD and GSH-Px suggesting that NaCl could alter the activity of these enzymes in salted pork. The ability of NaCl to reduce the activity of the antioxidant enzymes could be partially responsible for the lower oxidative stability of salted muscle foods.     

Retardation of haemoglobin-mediated lipid oxidation of Asian sea bass muscle by tannic acid during iced storage

Lipid oxidation mediated by haemoglobin from tilapia was monitored in washed Asian sea bass mince with and without added tannic acid (200 and 400 ppm) during 10 days of iced storage. Control samples (without tannic acid) had the highest peroxide value (PV) within the first 2 days and possessed the greater amount of thiobarbituric acid-reactive substances (TBARS) throughout the storage of 10 days (p < 0.05). With addition of tannic acid, the lipid oxidation of washed Asian sea bass mince was retarded, especially when the higher level (400 ppm) was used, as evidenced by lowered PV and TBARS. The retarded formation of volatile lipid oxidation products in the samples with added 400 ppm tannic acid was found. Sensory analysis revealed that samples with added 400 ppm tannic acid possessed lower fishy odour score, compared with the control sample and that with added 200 ppm tannic acid (p < 0.05).     

Expression of the catalase gene katA in starter culture Lactobacillus plantarum TISTR850 tolerates oxidative stress and reduces lipid oxidation in fermented meat product

The catalase gene katA of Lactobacillus sakei SR911 was cloned and expressed in Escherichia coli UM2 and Lactobacillus plantarum TISTR850 under strong lactococcal promoter P59 in E. coli-lactococcus expression vector pIL1020. The L. plantarum TISTR850 is a catalase-deficient strain isolated from local fermented meat product. The recombinant L. plantarum TISTR850 was shown to decompose hydrogen peroxide, and catalase activity approximately three times higher that of natural catalase-producing strain L. sakei SR911. The recombinant protein was also detected by in situ activity staining of the catalase enzyme. The recombinant L. plantarum TISTR850 did not accumulate hydrogen peroxide under glucose-limited aerobic conditions and remained viable after 60 h of incubation. The recombinant and host strain L. plantarum TISTR850 were used as starter cultures in the fermented meat product, and lipid oxidation was monitored over a 7-day storage at 20 degrees C determined as thiobarbituric acid-reactive substances (TBARS) value. The lipid oxidation level in the fermented meat product seeded with the catalase genetically modified starter culture L. plantarum TISTR850 was significantly lower than that of the natural catalase-deficient strain.     

The effect of dried galangal powder and its ethanolic extracts on oxidative stability in cooked ground pork

Thiobarbituric acid-reactive substances (TBARS) value, peroxide value (POV), conjugated diene and hexanal content were used to evaluate the effectiveness of dried galangal powder and its ethanolic extracts to increase oxidative stability in cooked ground pork during storage at 5 °C for 14 days. Dried galangal powder (0.05%, 0.10% and 0.15% w/w) and its ethanolic extracts (0.17%, 0.43% and 0.51% w/w) significantly (P<0.05) inhibited the formation of TBARS value, POV, conjugated diene and hexanal content in a dose-dependent manner where dried galangal powder at a concentration of 0.51% was the most effective; at the end of storage, TBARS values, POV, conjugated diene and hexanal content were 70.5%, 66.8%, 22.7% and 89.7%, respectively, less than the untreated sample. Addition of dried galangal powder to cooked ground pork was more effective than its ethanolic extract in controlling lipid oxidation. Furthermore, TBARS values and hexanal contents in cooked ground pork were highly correlated (r²=0.96; P<0.05). These results suggest that the application of dried galangal powder and its ethanolic extracts could enhance oxidative stability of meat or other lipid containing food systems.     

Lipolysis and lipid oxidation in bacon during curing and drying–ripening

Dry-cured bacons were processed using pig bacon belly as material by dry-salting and drying–ripening. Lipolysis and lipid oxidation in intramuscular lipids were studied by evaluating the changes in lipid composition, lipolytic enzymes and lipoxygenase (LOX) activities, peroxide value (POV) and TBARS during processing. Lipid composition showed a significant decrease (p < 0.05) in phospholipids and an increase (p < 0.05) in free fatty acids (r = −0.85, p = 0.0004). All lipolytic activities decreased (p < 0.05) with increasing process time. Acid lipase showed higher activity than did neutral lipase (p < 0.05) throughout the processing. LOX activity increased significantly during salting (p < 0.01) and thereafter decreased. High salt content inhibited acid lipase and phospholipase activities but promoted LOX activity. Both POV and TBARS decreased (p < 0.05) with temperature rising during the last ripening period, suggesting that rising temperature in this period could lower oxidation indices in products. LOX was closely correlated with TBARS (r = 0.94) but not with POV (r = 0.36), indicating that LOX could facilitate lipid secondary oxidation.