Effects of NaCl Concentration and Potassium Chloride Substitutions on the Thermal Properties and Lipid Oxidation of Dry‐Cured Pork

The thermal properties of cured meat are important for determining storage life and nutritional quality. However, few studies have focused on the thermal properties of dry‐cured pork, particularly in relation to salt level and type. In order to study the thermal properties of dry‐cured pork, we used differential scanning calorimetry (DSC) to evaluate the net heat energy (enthalpy, ΔH), onset (T_onset), and maximum (T_max) temperatures of different pork cuts salted with mixtures of chloride (NaCl and KCl) salts within the curing and ripening temperature range. Within the curing temperature range (?5 to 20 °C), the T_onset, T_max, and ΔH of cured meat treated with different NaCl : KCl mixtures were generally lower than for fresh meat, which indicates that the addition of NaCl or KCl can reduce the melting of lipids and water (especially lipids), in different pork cuts. Within the ripening temperature range (5 to 50 °C), heat absorption peaks in belly and leg cuts were between 29 and 33 °C. However, no obvious heat absorption peak was found in loin cuts. Compared to non‐KCl substitutions, a slightly higher KCl substitution could significantly (P < 0.05) enhance ΔH values of dry‐cured belly and leg cuts. The likely cause of this phenomenon is that high KCl substitutions promote lipid oxidation (r = 0.98, for belly; r = 0.95, for leg cuts). Therefore, KCl substitution should be no more than 30% (wt/wt), especially for high lipid pork, to prevent excessive melting and oxidation of lipids during the dry‐curing process.     

Effects of pork meat cut and packaging type on lipid oxidation and oxidative products during refrigerated storage (8 degrees C)

ABSTRACT:  Lipid oxidation and oxidative products as affected by pork meat cut, packaging method, and storage time were evaluated during refrigerated storage. Pork belly had higher pH and thiobarbituric acid reactive substance (TBARS) values than pork loin, and aerobic-packaged belly had higher TBARS than vacuum-packaged counterparts. Loin had higher free fatty acid (FFA) values than belly, and increased FFA values were observed with increased storage time. Peroxide values increased up to 7 d and decreased thereafter. Volatile compounds such as alkanes, aldehydes, ketones, and alcohols with high volatility in belly were higher than those in loin. Nonanoic acid, ethyl ester in belly, and hexadecanoic acid in loin might be considered as indices of lipid oxidation. Overall, vacuum packaging was better than aerobic packaging to retard lipid oxidation and production of oxidative products, and loin was more sensitive to lipid oxidation than belly.     

Evaluation of pre‐heating and extraction solvents in antioxidant and antimicrobial activities of garlic,and their application in fresh pork patties

The objectives of this study were to screen the optimum conditions for antioxidant and antimicrobial activities of garlic as affected by pre‐heating and different extraction solvents, and to evaluate the antioxidant and antimicrobial effects of these extracts in ground meat during refrigerated storage. Methanol extracted garlic had a greater total phenolic content, 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH)‐radical scavenging activity and reducing power than water extracted one (P < 0.05), whereas the latter had a greater yield and iron chelating ability than the former (P < 0.05). Moreover, water extract from fresh garlic (WEFG) and methanol extract from heated garlic (MEHG) produced an inhibition zone against Escherichia coli O157:H7 and Listeria monocytogenes. The addition of garlic extracts (WEFG, MEHG and their combinations WEFMEHG)) to pork patties decreased the pH, hunter a values (redness), thiobarbituric acid substances values and the number of total plate count and Enterobacteriaceae (P < 0.05), while the hunter b values (yellowness) increased (P < 0.05). Results of this study indicated that the use of the garlic extracts was able to control lipid oxidation and microbial growth in pork patties.     

Modeling dependence of growth inhibition of Salmonella Typhimurium and Listeria monocytogenes by oregano or thyme essential oils on the chemical composition of minced pork

The aim of this study was to compare the antimicrobial effect of selected essential oils (EOs) at concentration of 1% in minced pork from five different meat cuts (loin, ham, shoulder, neck, and belly) and to assess the influence of the chemical parameters of meat on EO efficiency, determined by the decrease of pathogens in comparison to a control in samples after storage at 3°C/7 d in a vacuum. The inhibition was significant (p < .05) only in minced pork from meat cuts with a fat content lower than 5% (leg, loin and shoulder). Salmonella enterica serovar Typhimurium was more sensitive than Listeria monocytogenes and oregano was more effective than thyme (p < .001). The inhibition of S. Typhimurium depended mainly on the fat content (logarithmic dependence) and to a lesser degree on the pH, whereas pH was not found to be a significant predictor in the case of L. monocytogenes. The results of this study show that only lean minced meat (with a fat content max. 5%) is a suitable matrix for pathogen control by EOs.     

Effects of onion on physicochemical properties,lipid oxidation and microbial growth of fresh pork patties

Onions with or without heating (100 °C, 30 min) were extracted with water or methanol, and antioxidant and antimicrobial activities of onion extracts were evaluated. Product characteristics of fresh pork patties containing various onion extracts were measured during refrigerated storage. Water extracts of onions showed higher extraction yield and iron chelating ability than methanol extracts (P < 0.05), whereas, the latter was more effective than the former in phenolic compounds and reducing power (P < 0.05). The addition of onion extracts [water extract from fresh onion (WEFO), methanol extract from heated onion (MEHO) and their combinations (WEFMEHO)] to pork patties decreased redness, increased yellowness, and inhibited lipid peroxidation (P < 0.05). One per cent of WEFMEHO in pork patties had antioxidant activities as effective as butylated hydroxyl toluene (BHT, 0.01%). Redness and yellowness decreased and increased with the addition of onion extract, respectively (P < 0.05).     

Evaluation of lipid oxidation and oxidative products as affected by pork meat cut, packaging method, and storage time during frozen storage (-10 degrees C)

ABSTRACT:  Lipid oxidation and oxidative volatiles as affected by pork meat cut and packaging method during frozen storage at –10 °C were evaluated. Pork belly cut had higher thiobarbituric acid reactive substance (TBARS) and pH values than did the loin, whereas the loin had higher free fatty acid (FFA) values than that of the belly cut. Peroxide values increased with increased storage time, but were not affected by pork meat cut and packaging method. Volatiles with carbon numbers less than 10 in the belly cut were higher than those in the loin cut, whereas those with carbon numbers greater than 10 in the loin cut were higher than those in belly cut. Most volatiles were decreased with increased storage time, except for propane. Both 4-pentenal and 4-methyl-2-hexanone in the belly cut showed a positive correlation with FFA, whereas 2,4-dimethyl-1-heptene and 9-octadecenal in the loin cut were positively correlated with TBARS and FFA, respectively, even though the values were not high enough to predict the degree of lipid oxidation.     

Role of precursors on greening in crushed garlic (Allium sativum) bulbs, and its control with freeze-dried onion powder

BACKGROUND: Lachrymatory factor (LF) synthase in onion bulbs reacts with S‐1‐propenyl‐L ‐cysteine sulfoxide (1‐PeCSO), a key compound in garlic greening. In this study, freeze‐dried onion powder containing LF synthase was used in treatments to control garlic greening. Prior to the use of freeze‐dried onion powder to treat greening garlic bulbs, model reactions were conducted to confirm the reactivity of 1‐PeCSO in onion bulbs to garlic greening. RESULTS: While pink pigments were generated from 1‐PeCSO, green pigments were produced from the combination of 1‐PeCSO and S‐2‐propenyl‐L ‐cysteine sulfoxide (2‐PeCSO). However, pigments were formed in the systems containing 1‐PeCSO, amino acid and alliinase. Even non‐greening garlic bulbs stored at 20 °C turned green with the reaction of 200 g L^?1 1‐PeCSO; therefore 1‐PeCSO isolated from onion bulbs had the same role as 1‐PeCSO in garlic bulbs in terms of greening. Onion bulbs turned green after the addition of 600 g L^?1 2‐PeCSO. The addition of freeze‐dried onion powder inhibited garlic greening, and treatment with 15 g kg^?1 onion powder gave the best storage stability of crushed garlic bulbs. CONCLUSION: The addition of freeze‐dried onion powder inhibited the greening in crushed garlic bulbs, and treatment with 15 g kg^?1 onion powder gave the best storage stability of crushed garlic bulbs. Copyright © 2011 Society of Chemical Industry     

Molecular Identification of Economically Motivated Adulteration of Red Pepper Powder by Species-Specific PCR of Nuclear rDNA-ITS Regions in Garlic and Onion

Economically motivated adulteration (EMA) of food is a matter of great concern in Korea due to its unfavorable effects on public distribution orders. EMA of red pepper powder is typically done with a mixture of garlic (Allium sativum) and onion (Allium cepa), leading to a reduction in red pepper powder content. To establish a rapid and accurate detection method for EMA red pepper powder, we designed species-specific PCR primers based on the internal transcribed spacer regions of garlic and onion DNA. Among the examined DNA extraction methods, the DNA extraction kit with a silica gel column was found to be a time-saving, high-purity, and high-yield method. When the designed species-specific PCR primers were used for designed EMA red pepper powder with different mixture ratios of garlic and onion, the target ingredients were detected in a concentration-dependent manner. Furthermore, duplex PCR allowed specific simultaneous detection of garlic and onion. Real-time quantitative PCR assay was successfully used to detect garlic and onion quantitatively in binary mixed samples containing as little as 0.05 % of these components. When we examined EMA red pepper powder collected from the Ministry of Food and Drug Safety using a conventional PCR assay, the newly designed PCR primers successfully detected the target ingredients.     

Effect of garlic, onion, and their combination on the quality and sensory characteristics of irradiated raw ground beef

Irradiated raw ground beef had lower a*- and b*-values than nonirradiated ones regardless of garlic or onion treatment at 0 d. Irradiation increased TBARS values of control ground beef, but addition of 0.5% onion or 0.1% garlic+0.5% onion reduced oxidative changes during storage. Addition of garlic or onion greatly increased the amounts of sulfur compounds, but the increase was greater with garlic. With irradiation, the profiles and amounts of S-volatiles in raw ground beef changed significantly. However, the intensity of irradiation aroma in irradiated raw ground beef with garlic or onion was similar to that of the nonirradiated control. This indicated that some of the sulfur compounds unique to garlic or onion interacted with common sulfur compounds detected in irradiated meat and masked or changed the odor characteristics of irradiated raw ground beef. It was concluded that >0.5% onion or <0.01% garlic would be needed to mask or prevent irradiation aroma in irradiated raw ground beef.     

Freeze-dried fresh onion powder prevents green discolouration (greening) in macerated garlic

Green discolouration (greening) of macerated garlic products is a major concern in the garlic-processing industry, and is caused by reactions between free amino acids and 2-propenyl 1-propenyl (2-Pe/1-Pe) thiosulphinates in the garlic. Efficacy of freeze-dried fresh onion powder that contains the active onion enzyme lachrymatory factor synthase (LFS) to prevent greening in processed garlic was evaluated. LFS converts 1-propenesulphenic acid to the volatile lachrymatory factor (LF). We hypothesised that this conversion would decrease the production of 2-Pe/1-Pe thiosulphinates, and thus, would reduce the subsequent discolouration of the garlic. Cooked onion powder added to fresh garlic, which was equivalent to adding crude 1-PeCSO, resulted in intensified green discolouration and increased 2-Pe/1-Pe thiosulphinate levels. On the other hand, fresh onion powder added to fresh garlic (0.5 g powder to 100 g fresh garlic) prevented greening and decreased the 2-Pe/1-Pe thiosulphinate levels. Similarly, a crude onion enzyme solution prevented greening in a garlic homogenate. The 2-propenyl 2-propenyl thiosulphinate (allicin) content was inconsistently altered by the addition of onion powder. However, the expected production of LF by the fresh onion powder or enzyme solution was not detected by gas chromatography, possibly due to changes in the sample matrix. This method using fresh onion powder is an effective technique for preventing greening of fresh garlic that does not use artificial food additives or cause safety concerns.     

葱姜蒜混合物对炖煮猪肉感官品质、脂肪氧化及脂肪酸组成的影响

研究了不同添加量葱姜蒜混合物(onion-ginger-garlic,OGG)(5%、10%、15%)对炖煮猪肉感官品质(色泽、质地、滋味、香气)、基本理化指标(脂肪和水分)、脂肪氧化程度(过氧化值(POV)和硫代巴比妥酸值(TBA))及脂肪酸组成的影响。结果表明:OGG的添加能够提高炖煮猪肉的感官品质、改善肉的持水力,且随着OGG添加量的增大,炖煮猪肉的持水力显著提高(P0.05)。OGG能够抑制炖煮猪肉过氧化物及TBARS的产生,且添加量为15%的效果最显著(P0.05)。炖煮猪肉中添加OGG能显著抑制猪肉脂肪酸氧化,尤其是不饱和脂肪酸的氧化,且随着添加量的增加其抑制效果也明显提高。此外,OGG的添加还影响炖煮猪肉脂肪酸含量,添加OGG制得的炖煮猪肉,其单不饱和脂肪酸和多不饱和脂肪酸含量显著升高(P0.05),提高了不饱和脂肪酸(UFA)和饱和脂肪酸(SFA)的比例(P0.05),从而改善了猪肉的营养价值。     

Investigation of food products containing garlic or onion for a false positive sulphite response by LC-MS/MS

ABSTRACT

In the US, sulphites must be declared on the label if they are present in concentrations greater than 10 mg/kg (determined as) SO₂ because an allergic-like response has been reported in a small subset of the population upon consumption of sulphite-containing products. The most widely used method for sulphite determination, the optimised Monier-Williams (OMW), produces false positive results with vegetables from the Allium (garlic) and Brassica (cabbage) genera due to extraction conditions that are thought to cause endogenous sulphur compounds to release SO₂. Recently, an LC-MS/MS method was developed for sulphites but has only been tested with samples that are 100% Allium or Brassica. Since regulatory samples may contain these vegetables as ingredients, additional investigations were necessary to determine the potential extent of false positives. Four blank matrices, chips, phyllo shells, hummus, and quinoa were spiked with various concentrations of onion and garlic powders. The sulphite concentrations were determined using an LC-MS/MS method. The matrix is extracted with a buffered formaldehyde solution, converting free and reversibly bound sulphite to the stable formaldehyde adduct, hydroxymethylsulfonate (HMS). It was determined that even at concentrations up to 8% garlic powder or 2% onion powder, the measured sulphite concentration was below the 10 mg/kg SO₂ labelling threshold. Commercial dried garlic powders were evaluated to determine the variation in responses that might be encountered in future regulatory samples. Recovery studies were conducted to determine if these methods would detect added sulphite. The ability to eliminate false positives due to these ingredients will result in a greater reliability in the accurate determination of added sulphite to ensure compliance with labelling requirements.     

Quality, palatability and weight loss of pork as affected by electrical stimulation

Forty-five swine (n = 15, stress-susceptible pigs, fasted for 18 h; n = 15, normal pigs, fasted for 48, 60 or 72h; n = 15, normal pigs, fasted for 18 h) were slaughtered. One side of each pig was electrically stimulated (ES)-550 V, 2-6 A, seventeen impulses, 1·8 s on and 1·8 s off per impulse-and the opposite side was not stimulated (NS). Ham and loin temperatures were monitored at 12 and 24 hours post mortem. Carcass quality-marbling, loin eye colour, loin eye firmness, subcutaneous fat firmness and belly firmness-was evaluated at 24 hours post mortem. Sides were fabricated into four lean cuts at 48 hours; cuts were placed on open metal racks in a 2°C cooler and weight loss was measured after 24, 48 and 72 hours storage. At 120 hours post mortem, loin chops were cut, frozen (-24°C for 45 days) and subsequently used to determine thaw loss, cooking loss, Warner-Bratzler shear (WBS) force and palatability. Ham temperatures (12 h) were significantly (P < 0·05) lower for the ES sides from the stress-susceptible, short-fast (SSF) group but not for normal, long-fast (NLF) or normal, short-fast (NSF) groups. ES produced lighter coloured, softer loin eyes in the SSF group but darker coloured, firmer loin eyes and firmer subcutaneous fat in the NLF group. No significant differences (P > 0·05) were detected for thaw loss, cooking loss, palatability ratings or WBS values between ES and NS in the SSF group but chops from ES sides of NLF animals had significantly (P < 0·05) higher ratings for muscle fibre tenderness, overall tenderness and overall palatability. Weight losses of the lean cuts from the ES sides were higher (P < 0·05) than those from NS sides in only three of sixty comparisons of cuts from the three groups of swine. These data suggest that ES had very minimal effects on quality, palatability or weight loss of pork.     

Addition of garlic or onion before irradiation on lipid oxidation, volatiles and sensory characteristics of cooked ground beef

Addition of 0.5% onion was effective in reducing lipid oxidation in irradiated cooked ground beef after 7 day storage. Addition of garlic or onion greatly increased the amounts of sulfur volatiles from cooked ground beef. Irradiation and storage both changed the amounts and compositions of sulfur compounds in both garlic- and onion-added cooked ground beef significantly. Although, addition of garlic and onion produced large amounts of sulfur compounds, the intensity of irradiation odor and irradiation flavor in irradiated cooked ground beef was similar to that of the nonirradiated control. Addition of garlic (0.1%) or onion (0.5%) to ground beef produced a garlic/onion aroma and flavor after cooking, and the intensity was stronger with 0.1% garlic than 0.5% onion treatment. Considering the sensory results and the amounts of sulfur compounds produced in cooked ground beef with added garlic or onion, 0.5% of onion or less than 0.1% of garlic is recommended to mask or change irradiation off-odor and off-flavor.     

Antioxidative properties of onion peel extracts against lipid oxidation in raw ground pork

Onion peels extracted with various concentrations of ethanol were examined for their extraction yield, total phenolic content, DPPH scavenging activity, and reducing power. Onion peel extracted with 50% ethanol exhibited higher extraction yields, total phenolic content, and DPPH scavenging activity than extracts from distilled water, 70 or 95% ethanol. Thus, the antioxidative efficiency to inhibit lipid oxidation of ascorbic acid (0.05%) and 50% ethanol extract of onion peel (0.05, 0.1, and 0.2%) in raw ground pork was investigated during chilled storage (16 days). The pH of the samples decreased considerably during storage (p<0.05). Addition of ethanol onion peel extract significantly improved the thiobarbituric acid reactive substances and peroxide values in raw ground pork meat (p<0.05). Therefore, onion peel extract by 50% ethanol is a very effective inhibitor of lipid oxidation and has potential as a natural antioxidant in raw ground pork.     

Effects of distribution packaging method and storage time on the physical properties and retail display characteristics of pork

The sensory characteristics of pork chops from bone-in loins and Boston butts (n = 65 each) were affected little by primal loin and the butt packaging method (paper wrap, vacuum pack and gas flush) and storage time (7, 10 and 14 days) under industry conditions. However, loin chops fabricated from vacuum-packaged loins after 14 days of storage had less (P < 0·05) discoloration and two-toning than chops fabricated from other loins. All loin chops were placed in retail display and overwrapped with a polyvinyl chloride film after fabrication at each storage time. Vacuum-packed butts stored for 10 and 14 days produced chops with less discoloration and two-toning, and higher overall appearance scores (P < 0·05) compared to chops from paper-wrapped or gas-flushed cuts. Vacuum-packaging resulted in higher quality retail cuts than paper-wrapped or gas-flushed packaging. Thus, it is recommended that the pork industry and retail distribution system utilize vacuum-packaging as the primary method to store and ship fresh pork before retail sale.     

Antioxidant and antimicrobial effects of garlic in chicken sausage

The antioxidant and antimicrobial effects of equivalent concentrations of fresh garlic (FG), garlic powder (GP) and garlic oil (GO) were investigated against lipid oxidation and microbial growth in raw chicken sausage during storage at 3°C. The antioxidant activities were compared to that of a standard synthetic antioxidant; butylated hydroxyanisole (BHA). The initial mean levels of thiobarbituric acid (TBA) value and peroxide value (POV) were 0.140 and 6.32, respectively. However after 21 days of storage, TBA and POV ranged from 0.151 to 4.92, respectively, in FG (50 g/kg) formulated samples to 0.214 and 8.64, respectively, in GO (0.06 g/kg) formulation. Addition of either garlic or BHA (0.1 g/kg) significantly delayed lipid oxidation when compared with control. The antioxidant activities of the various materials added followed the order FG>GP>BHA>GO. On the other hand, the initial aerobic plate count (APC) in the samples was 4.41 log₁₀ CFU/g. Addition of FG (30 g/kg) or GP (9 g/kg) significantly reduced the APC and, subsequently, the shelf-life of the product was extended to 21 days. However, addition of GO or BHA resulted in no significant difference in APC when compared with control. Sensory analysis indicated that FG had a significant stronger flavor than the other sausage formulations. The results suggest that fresh garlic and garlic powder, through their combined antioxidant and antimicrobial effects, are potentially useful in preserving meat products.     

Microbiological Contamination and Primal Cut Yields of Skinned and Scalded Pork Carcasses

Microbiological contamination was determined in core samples from the surface of the ham, shoulder, belly and back of skinned and scalded pork carcasses. Aerobic plate counts of mesophilic organisms indicated that ham and shoulder areas of scalded carcasses had higher bacterial numbers than skinned carcasses. Contamination on the back of the carcass was similar for skinned and scalded carcasses, while skinned carcass bellies had slightly higher counts than did scalded bellies. Numbers of psychrotrophic bacteria were negligible in all cases. Weights of primal cuts were compared in skinned and scalded carcasses by alternately skinning one side of each of 23 pork carcasses, while the other side was left skin-on. Belly, picnic shoulder and ham yields were less for skinned sides, while the loin and Boston shoulder were not affected.     

7-Ketocholesterol and 7-hydroxycholesterol in pork meat and its gravy thermally treated without additives and in the presence of onion and garlic

The effect of onion and garlic on the formation of two cholesterol oxidation products (COPs): 7-ketocholesterol and 7-hydroxycholesterol was evaluated by comparing their concentrations in meat and gravy samples obtained from three pork dishes prepared in the presence and absence of these flavourings. The concentration of these compounds in meat samples was between 82.4 and 1331.6 ng/g of cooked meat. Gravies contained lower amounts: from 18.3 to 45.6 ng/g of cooked meat. The addition of onion (30 g/100 g of meat) caused a decrease in 7-ketocholesterol and 7-hydroxycholesterol concentrations in all of the investigated pork dishes by 9.5–79%, whilst the addition of 15 g of garlic to 100 g of meat lowered the concentration by 17 to 88%. The greatest decrease was found in grilled minced chops. The quantitative assessment of 7-ketocholesterol and 7-hydroxycholesterol was carried out by thin-layer chromatography with densitometric detection.     

Survival during storage and sensory effect of potential probiotic lactic acid bacteria Lactobacillus acidophilus Bauer and Lactobacillus casei Bif3′/ IV in dry fermented pork loins

The objective of this work was to study the survival of two potential probiotic strains (Lactobacillus acidophilus Bauer and Lactobacillus casei Bif3′/IV) in pork loins both with the verification of the possibility of fermented loin development in relation to sensory and microbiological criteria. Six different samples of loins were prepared while as 3 weeks of ripening process and 6 months of storage. The obtained results indicated that highest sensory quality of fermented pork loin after storage was observed in the case of sample produced with L. acidophilus Bauer and with 0.2% glucose addition. The highest count of lactic acid bacteria was observed in the case of the sample with L. casei Bif3′/IV. The results of the study demonstrate that application of probiotic strain L. acidophilus Bauer for pork loins fermentation could assure the satisfying quality regarding sensory and microbiological criteria and can be used for dry fermented loin production.