Changes in the content of biologically active polyamines during beef loin storage and cooking

Dietary polyamines putrescine (PUT), spermidine (SPD) and spermine (SPM) participate in numerous human physiological processes, including tumour growth. Reliable information on their contents in foods is thus needed. Data for processed beef are very limited. Nine experiments with beef loin (longissimus lumborum) were, therefore, carried out. Loin cuts were stored at −18 °C for 178 days or beef was stored aerobically, vacuum-packaged (VP) and packaged in a modified atmosphere (MA; 70% N₂ and 30% CO₂, v/v) at +2 °C for 9, 21 and 21 days, respectively. The effects of three usual cooking treatments were also tested. Polyamines were determined after extraction with perchloric acid as dansyl derivatives using an HPLC method. Only SPM was detected at initial levels of 23.5–27.5 mg kg⁻¹, PUT and SPD contents were below the detection limits of 1.2 and 1.7 mg kg⁻¹, respectively. SPM content increased during the initial weeks of frozen storage and then gradually decreased to about 70% of the initial values at the end of the storage period (P < 0.05). No apparent SPM decrease was observed during aerobic storage for 9 days, while in VP and MA variants the losses were about 20% of the initial values on day 21 (P < 0.05). Slightly higher mean SPM losses were observed during boiling and stewing with and without added water. The differences among the cooking treatments were not significant. However, significant differences were observed among the loins used.     

Concentration of biologically active polyamines in meat and liver of sheep and lambs after slaughter and their changes in mutton during storage and cooking

Putrescine (PUT), spermidine (SPD) and spermine (SPM) concentrations using a UPLC method, in chilled mutton, lamb and livers 24 h after slaughter were determined. PUT concentrations were quantifiable only in some samples. Mean SPD concentrations were 4–6, 13.5 and 16.8 mg kg⁻¹ in the meats, sheep and lamb livers, respectively. The respective SPM concentrations were 17–25, 128 and 79 mg kg⁻¹. SPD and SPM losses of about one fifth and half of the initial level, respectively, were apparent in mutton loins stored at −18 °C for 6 months. Significant losses of SPD and SPM were found in mutton loins stored aerobically, vacuum-packaged or in a modified atmosphere at + 2 °C. Boiling and stewing of mutton legs caused SPD and SPM losses of about 40% and roasting of about 60% of the initial content.     

Content of polyamines in beef and pork after animal slaughtering

Dietary polyamines putrescine (PUT), spermidine (SPD) and spermine (SPM) participate in an array of important human physiological roles, including tumour growth. Physicians and dieticians thus need reliable information on polyamine contents in foods. However, data for both fresh and processed beef and pork are limited. We therefore, determined the initial content of the polyamines, 24 h after slaughtering, in sirloin and rump of 63 young bulls and in loin and leg of 27 pigs of both genders. Polyamines were determined as N-benzamides by micellar electrokinetic capillary chromatography (MECC). PUT and SPD contents in most of the meat samples were negligible. Mean SPM contents were about 22±6 mg kg⁻¹ in sirloin and rump. No significant correlations at P<0.05 were found between the SPM contents in sirloin and rump, likewise between SPM contents and the age and between live weight and type of the efficiency of the bulls. Mean SPM contents in loin and legs of barrows were 26.1±7.0 and 28.4±8.5 mg kg⁻¹, respectively, while the corresponding values in gilts were 22.3±10.6 and 18.3±9.3 mg kg⁻¹.Between the genders the difference in SPM contents in the legs was significant. SPM contents relatively vary widely within the individual kinds of meat, which complicates application of the results for the controlled human nutrition.     

Concentration of biologically active polyamines in rabbit meat, liver and kidney after slaughter and their changes during meat storage and cooking

The concentration of putrescine (PUT), spermidine (SPD) and spermine (SPM) was determined in chilled meat and kidneys of 18 rabbits and in liver of 12 animals 24 h after slaughter. Very low PUT concentrations were detected only in kidneys. Mean SPD levels were 2.2, 2.2, 61.7 and 32.7 mg kg^− 1 in saddle, leg, liver and kidneys, respectively. The respective SPM concentrations were 14.7, 8.0, 115 and 88.4 mg kg^− 1. SPD and SPM losses of about one third of the initial levels were apparent in saddles stored at − 18 °C for 8 months. Losses of both polyamines of about 15-20% of the initial concentrations were found in saddles stored aerobically at + 2 °C for up to 9 days. Stewing of saddles caused significant SPD and SPM losses of about 20-25%, while upon roasting and pan-roasting without oil a decrease of about 50% of the initial concentration was observed.     

Biologically active polyamines in beef, pork and meat products: A review

Dietary polyamines (PAs) putrescine (PUT), spermidine (SPD) and spermine (SPM) participate in an array of roles in human metabolism. Nevertheless, under some physiological conditions they can be undesirable. Meat and meat products are among important sources of PAs in human nutrition, mainly of SPM. The usual contents of PUT, SPD and SPM in fresh beef and pork are <2, <5 and 20-40mgkg(-1), respectively. Current information on changes of PAs during meat storage corresponds with PUT formation by bacterial activity mainly of pseudomonads and Enterobacteriaceae. However, data on SPD and SPM changes during meat chill-storage have been inconsistent. Culinary processing of meat probably does not change SPD and SPM levels. PUT can be formed in different meat products in relation to the microbial population of the raw materials used and the hygienic level of manufacturing process. SPD and SPM contents seem to remain stable during processing of non-fermented meat products or decrease during dry-cured ham ripening. PUT contents increase commonly to 60-140mgkg(-1) in dry spontaneously fermented sausages, however, contents up to several hundreds mgkg(-1) are not extraordinary. Starter cultures are usually able to decrease PUT formation considerably. SPD and SPM contents in dry fermented sausages are comparable with levels typical for fresh meat. Data on SPD and SPM changes during ripening and storage are inconsistent. A decrease of the both polyamines during a storage period has been usually reported.     

Changes in the content of biologically active polyamines during storage and cooking of pig liver

Dietary polyamines putrescine (PUT), spermidine (SPD) and spermine (SPM) participate in numerous human physiological processes, including tumour growth. Eight experiments with pig liver were carried out. In two, livers were stored at -18°C for 168 days, in four, livers were stored aerobically (AE), vacuum-packaged (VP) and packaged in a modified atmosphere (MO; 70% N(2) and 30% CO(2), v/v) at +2°C for 9, 21 and 21 days, respectively, and in two, the effects of four cooking treatments were tested. Polyamines were determined as dansyl derivatives using an HPLC method. Distribution of both SPD and SPM in the four main liver lobes was homogenous. The initial SPD and SPM contents in 14 livers 24h after slaughter were 23.3±6.7 and 94.5±19.6mgkg(-1), respectively. The putrescine content was below the limit of detection. The content of SPD and SPM decreased during frozen-storage to about 70% of the initial values. On day-9 of storage, mean SPD and SPM contents decreased to about 85% of the initial values in livers stored in MO and to about 75-80% in AE and VP at 2°C. The decrease continued more extensively in VP than in MO. PUT was detected from day-15 of VP and MO storage. There was a significant decrease in SPD and SPM, to about 70-60% of the initial content during cooking.     

Biogenic amines and polyamines in liver,kidney and spleen of roe deer and European brown hare

Cadaverine (CAD), histamine (HIS), tyramine (TYR) and the polyamines putrescine (PUT), spermidine (SPD) and spermine (SPM) were determined in liver, kidney and spleen of hunted roe deer (n = 39) and European brown hare (n = 20) 3 and 6 h post mortem, respectively. Median concentrations (mg/kg fresh weight) of CAD and TYR were <5 mg/kg for organs of both species, whereas median HIS concentrations were higher in spleen (14.6 and 11.6 mg/kg for hare and roe deer, respectively) and lowest in liver. Maximum PUT concentration was 72.9 mg/kg, but median values were ≤7.8 mg/kg. Mean SPD concentrations were 8.5, 10.7 and 42.9 mg/kg for liver, kidney and spleen of roe deer, and 37.2, 24.4 and 52.0 mg/kg for hare. Mean SPM concentrations were higher (94.6, 79.9, 102.2 and 111.2, 82.8, 91.1 mg/kg, respectively). SPM concentrations in the organs of the male roe deer were significantly higher than in those of females. SPM:SPD ratios (weight base) were in the order of 2:1 for spleen, and higher for liver and kidney. SPM and SPD were correlated significantly (r = 0.42–0.47). Although variations of polyamine concentrations are partially associated with species, organ, age and gender, the relative contribution of individual factors deserves further study.     

Contents of biologically active polyamines in chicken meat,liver, heart and skin after slaughter and their changes during meat storage and cooking

Dietary polyamines, putrescine, spermidine (SPD) and spermine (SPM), participate in an array of important physiological roles, including tumour growth. Thus, reliable information on polyamine content in foods has been needed. We therefore determined polyamine contents in chilled chicken meat and giblets (n = 20) and skin (n = 10) 24 h after slaughter. The polyamines were determined, after extraction with perchloric acid, as dansyl derivatives, using an HPLC method. Mean SPD values were 4.8, 10.2, 11.4, 48.7 and 12.1 mg kg⁻¹ and SPM values were 36.8, 38.0, 24.3, 133 and 82.7 mg kg⁻¹ in breast, thigh, skin, liver and heart, respectively. Significant statistical correlations between SPD and SPM contents were observed in breast, thigh, skin and liver, whereas correlations were insignificant in heart. An increase of SPD and SPM was apparent in breasts and thighs stored at −18 °C for 6 months; however, it was significant only for SPM in thighs. The losses of both SPD and SPM were statistically insignificant during storage of aerobically packaged breasts up to 9 days at +2 °C. A significant decrease of SPM to about 60% of the initial contents was observed in both vacuum-packaged and in modified atmosphere (20% CO₂ and 80% O₂)-stored breasts on day 21 at +2 °C. For both SPD and SPM, roasting, grilling and frying of fresh breasts caused losses of about 40–60% of the initial contents (higher than boiling and stewing). Similarly, losses of SPM, due to roasting of breasts frozen for 3 or 6 months, were higher than those caused by stewing. Putrescine was detected only sporadically and at levels close to the detection limit of 1.0 mg kg⁻¹ (fresh matter).     

Biologically active polyamines in pig kidneys and spleen: Content after slaughter and changes during cold storage and cooking

Polyamines putrescine, spermidine (SPD) and spermine (SPM) were determined as dansyl derivatives using an HPLC method. Distribution of SPD and SPM in pair kidneys was homogenous. The mean SPD and SPM contents in pig kidneys 24 h after slaughter were 9.39 ± 3.35 and 53.1 ± 14.0 mg kg⁻¹, respectively with no significant differences between barrows and gilts. Putrescine content was below the detection limit of 1.2 mg kg⁻¹. In kidneys stored aerobically or vacuum-packaged at 2–3 °C for 7 and 21 days, respectively, SPD and SPM decreased significantly. Stewing decreased both polyamines more extensively in kidneys processed on day-1 after slaughter than on day-7 after storage at 2–3 °C. The mean SPD and SPM in 10 spleens 24 h after slaughter were 36.7 ± 5.70 and 34.0 ± 7.64 mg kg⁻¹, respectively. Thus, both pork kidney and spleen are foods with a high level of SPM and SPD.     

DISTRIBUTION PACKAGING METHOD AND STORAGE TIME EFFECTS ON THE MICROBIOLOGICAL CHARACTERISTICS AND INCIDENCE OF THE PATHOGENS LISTERIA MONOCYTOGENES AND SALMONELLA IN PORK1

Microbiological and yield characteristics were determined on bone-in pork loins and Boston butts (n = 65 each) that were selected from a commercial facility and subjected to one of three packaging treatments: (1) paper wrapped, (2) modified atmosphere packaging (66% O, 2.26% CO₂ and 8% N₂), and (3) vacuum packaging. Cuts were stored up to 21 days at 0 ± 2C for yield characteristics and an added 28 and 35 days for microbiological characteristics. Treatment and storage effects on the incidence of the pathogens Listeria monocytogenes, Salmonella and numbers of aerobic bacteria, lactic acid bacteria and coliforms were determined. The amount of purge was variable (100 to 500 g) among packaging treatments. The vacuum packaged and modified atmosphere packed pork loins and butts had lower aerobic plate counts (P < .05) compared with the paper wrapped loins and butts. The numbers of Listeria species decreased at a greater rate for the vacuum packaged and modified atmospheric packaged pork loins compared with the paper wrapped loins. No Salmonella were found on meat from any packaging treatment or storage time. The microbial quality of pork loins and butts can be improved by using vacuum packaging compared with paper wrapping or modified atmosphere packaging.     

Content of biologically active polyamines in livers of cattle, pigs and chickens after animal slaughter

Dietary polyamines putrescine (PUT), spermidine (SPD) and spermine (SPM) participate in an array of important human physiological roles, including tumour growth. Physicians and dieticians thus need reliable information on polyamine contents in foods. However, data for livers are lacking. We determined therefore the content of these polyamines 24 h after slaughter in livers of young bulls, cows, pigs and chicken in 58, 19, 36 and 38 samples, respectively. Polyamines were determined as N-benzamides by micellar electrokinetic capillary chromatography. Mean PUT contents about 25 mg kg⁻¹ were found in cattle livers, while very low or negligible contents were determined in livers of the other animals. Extremely high mean SPD contents of 122 and 161 mg kg⁻¹ were found in livers of bulls and cows, respectively and mean levels of 32 and 57 mg kg⁻¹ in livers of pigs and chicken. An opposite relation was observed for SPM. Its mean contents were 43, 35, 115 and 120 mg kg⁻¹ for bulls, cows, pigs and chicken livers, respectively. Thus, livers of the tested animal species belong among foods with the highest polyamine contents. However, the contents ranged very widely, that makes application of the results for the control of human nutrition rather difficult. Polyamine contents in bovine blood were found to be below the detection limits of 2.1, 1.0 and 1.4 mg kg⁻¹ for PUT, SPD and SPM, respectively. Thus, the blood content did not contribute to the substantial polyamine contents in bovine liver found in this study.     

Polycyclic aromatic hydrocarbons (PAHs) in traditional and industrial smoked beef and pork ham from Serbia

Smoked beef and pork ham samples were analysed during process of smoking (after packing and storing) for the presence of the 16 EU priority PAHs via Fast GC/HRMS method. This study showed that there are differences in PAH contents between final smoked beef ham samples from traditional smokehouse (TS) (3.9 μg kg⁻¹) and industrial smokehouse (IS), (1.9 μg kg⁻¹). Also there is a difference in PAH contents in final smoked pork ham samples (4.9 μg kg⁻¹, TS; 4.2 μg kg⁻¹, IS). In beef and pork ham samples from the same smokehouse different PAH contents were observed during smoking. The highest content of examined PAHs in all beef and pork ham samples during smoking showed benzo[c]fluorene (BcL) (beef ham: from 0.3 μg kg⁻¹ to 1.5 μg kg⁻¹; pork ham: from 0.2 μg kg⁻¹ to 2.1 μg kg⁻¹).The maximum level for benzo[a]pyrene (BaP) of 5 μg kg⁻¹ in smoked meat products was not exceeded in any samples. Correlation statistic analysis (P < 0.05) of obtained contents from samples both from TS and IS showed that BaP is a good marker both for 16 EU priority PAHs and 12 IARC probably and possibly carcinogenic PAHs (IS: R _BaP/Σ16PAHs = 0.95, R _BaP/Σ12PAHs = 0.96; TS: R _BaP/Σ16PAHs = 0.71, R _BaP/Σ12PAHs = 0.88).     

Shelf Life of Pretreated Dried Tomato

Determining the shelf life has become a factor of major importance in the development of foods designed to meet consumer demands in terms of quality and safety. The goal of the present study was to investigate the shelf life of vacuum-packed dried tomatoes, stored at both room and refrigeration temperature (4 °C) for a period of 180 days. The following determinations were performed during the storage period studied: microbiological analysis, instrumental color, lycopene, and ascorbic acid. Sorption isotherms were determined at both temperatures (room temperature and 4 °C). The microbiological quality of vacuum-packed dried tomatoes remained unchanged during 180 days for the refrigerated samples and 90 days for the samples stored at room temperature. The rate constant (k) of lycopene degradation of the refrigerated samples and the samples stored at room temperature was 3.209 × 10⁻⁵ and 12.994 × 10⁻⁵/day, respectively. The rate constant (k) of ascorbic acid degradation was 3.339 × 10⁻⁴/day for cold storage and 76.655 × 10⁻⁴/day for storage at room temperature. The tomatoes stored at room temperature were subjected to analysis over 90 days of storage, period after which both the appearance and sensory characteristics of the product fell below the levels of consumer acceptability. As for the tomatoes stored at refrigeration temperature, the original sensory characteristics were maintained throughout the entire storage period of 180 days.     

Effect of Hydrodynamic Pressure Processing on the Processing and Quality Characteristics of Moisture-Enhanced Pork Loins

ABSTRACT: The objective of this study was to determine the influence of hydrodynamic pressure processing (HDP) and aging on the processing characteristics and final meat quality of moisture-enhanced pork loins. Boneless pork loins (n = 24) were split into 3 portions and assigned treatments: control (non-HDP treated, brine-injected), HDP treated before brine-injection, or HDP treated after brine-injection. Pork loins were injected with a salt/phosphate/water solution to 110% of original weight on day 0, intermittently tumbled 3 h, and then held overnight. Meat quality and protein characteristics were measured on days 1 and 8. HDP-treated loins had greater (P < 0.05) brine retention after overnight equilibration and a higher (P < 0.05) processing yield than controls. Warner–Bratzler shear force and expressible moisture decreased (P < 0.0001) with aging from days 1 to 8, but were not significantly affected by either HDP treatment. When the drip loss data from HDP treatments were pooled, HDP samples had lower drip loss values than controls. L* and b* measurements exhibited significant HDP by aging interaction effects, but a* was not influenced by either HDP or aging. Myofibrillar protein solubility and gel electrophoresis measurements of protein degradation were influenced by aging treatments. Data from this study suggest that HDP may have beneficial effects on the processing and final product quality of moisture-enhanced pork loins. Practical Application: This study demonstrates that hydrodynamic pressure processing (HDP) is an effective postharvest technology for improving the processing and meat quality characteristics of moisture-enhanced pork loin products, benefiting both meat processors and consumers.     

Effects of dietary α-linolenic acid on the fatty acid composition, storage stability and sensory characteristics of pork loin

Effects of dietary α-linolenic acid on the fatty acid composition, storage stability and sensory characteristics of cooked pork were studied. Dietary α-linolenic acid (LNA) significantly (p < 0.05) increased the proportion of n−3 fatty acids and the degree of unsaturation in the neutral lipids and phospholipids. The increases in n−3 fatty acids were observed in the total lipids, triglycerides, phosphatidylethanolamine and phosphatidylcholine, and mainly consisted of C18:3n3, C20:5n3 and/or C22:5n3.The thiobarbituric acid reactive substances (TBARS) values (mg malondialdehyde per kg meat) of cooked vacuum packaged loins remained below 1.5, but in loose packaged loins TBARS values increased more than 3 times those of 0 time values during 2-day storage at 4 °C. The TBARS values of loins after LNA-enrichment were significantly higher than those of the control in both vacuum and loose packaging, and the increase of unsaturation in fatty acids had a strong prooxidant effect. The increase in dietary LNA enrichment increased oxidation (TBARS values) and had a detrimental effect on the acceptability of cooked pork loins held for 2 days in loose packaging.     

Effects of time and temperature on the viability of Toxoplasma gondii tissue cysts in enhanced pork loin

Enhanced or pumped pork products represent a significant proportion (40 to 50%) of the commercially available pork cuts available to consumers at the retail level. In a previous study, pork loins containing viable Toxoplasma gondii tissue cysts were pumped with solutions containing 2% sodium chloride or 1.4% or higher potassium or sodium lactate and stored at 4 degrees C for 7 days. This treatment prevented transmission of T. gondii to cats. In the present study, enhanced pork loins were stored for 0, 8, 16, 24, 32, or 40 h at 4 degrees C and then fed to T. gondii-seronegative cats to determine how quickly the loss of tissue cyst viability occurred. In a second experiment, pork loins collected from pigs experimentally infected with T. gondii were stored at temperatures found in retail meat cases and then fed to T. gondii-seronegative cats to determine the effect of typical meat case storage temperatures on tissue cyst viability. In both experiments, cat feces were examined for 14 days after the infected meat meal to assess oocyst shedding. The results indicate that solutions containing 2% sodium chloride or 1.4% potassium or sodium lactate are effective within 8 h of injection for killing T. gondii tissue cysts in pork loins and that storage at meat case temperatures at or below 0 degrees C (32 degrees F) for 7 days also killed T. gondii tissue cysts in pork loins.     

Changes in Microflora and Other Characteristics of Vacuum-packaged Pork Loins irradiated at 3.0 kGy

Effects of 3.0-kGy irradiation on microflora and other attributes of fresh, vacuum-packaged pork loins were examined during storage (2–4°C, 98 days) and mishandling (24–25°C, 24 and 48 hr). Shelf life of pork chops from irradiated loins was determined at 5°C. Irradiated loins kept at 2–4°C tested negative for Salmonella spp., Campylobacter spp., Clostridium perfringens and Staphylococcus aureus. Yersinia spp. was detected in pork chops held at 5°C; this organism, C. perfringens and Aeromonas spp. were present in abused samples. In two irradiated samples Listeria monocytogenes was found. Irradiation reduced aerobic, anaerobic and Aeromonas spp. counts; lactobacilli were least affected. Chemical spoilage began after 91 days at 2–4°C. With irradiation, TBA values were unaffected but Hunter a color values increased.     

Characterisation and application of Halomonas shantousis SWA25, a halotolerant bacterium with multiple biogenic amine degradation activity

Biogenic amines are identified as toxicological substances in foods and may have detrimental effects on consumers’ health. In recent years, the application of microorganisms that can degrade biogenic amines has become an emerging method for their reduction. The degradation characteristics and application potential of a salt-tolerant bacterium Halomonas shantousis SWA25 were investigated in this study. H. shantousis SWA25 exhibited degradation activity against eight biogenic amines at 10–40°C (optimum, 30–40°C) and pH 3.0–9.0 (optimum, 6.0–7.0) in the presence of 0–20% (w/v) NaCl (optimum, 0%). Specifically, H. shantousis SWA25 degraded all tryptamine (TRY) and tyramine (TYR) in 6 h, all phenethylamine (PHE) in 9 h, 66.7% of histamine (HIM), 52.4% of cadaverine (CAD), 48.0% of spermidine (SPD), 42.9% of putrescine (PUT) and 42.0% of spermine (SPM) in 20 h at 30°C and pH 7.0 with shaking at 120 r min^?1. The enzymes from H. shantousis SWA25 responsible for degradation of biogenic amines were mainly amine oxidases located on the cell membrane. Further studies showed that H. shantousis SWA25 effectively degraded TRY, PHE, PUT, CAD, HIM and TYR in commercial fish sauce and soy sauce samples. Nevertheless, significant SPD and SPM degradation were not observed due to low initial concentrations. Therefore, H. shantousis SWA25 can be applied as a potential biogenic amines degradation bacterium in foods.     

Effects of dry aging of bone-in and boneless strip loins using two aging processes for two aging times

This experiment investigated the combined effects of two dry-aging methods (unpackaged and in a bag), two loin-cut styles (bone-in shell loins and boneless strip loins), and two aging times (21 and 28 days) on the physical, chemical, sensory, and microbial properties of dry-aged beef. Sections from shell and strip loin were assigned randomly to be aged unpackaged or aged packaged in a bag with high moisture permeability. Weight losses increased with aging time. Shell loins lost more (P < 0.05) weight during aging compared with strip loins; dry aging in a bag had less (P < 0.05) weight loss than unpackaged aging. There were no differences (P > 0.05) in any of the sensory traits between shell and strip loins or dry aging using a traditional method or in a bag. Dry aging in a bag creates positive effects on yields, no negative effects on product quality, and adds flexibility and control of the aging environment.     

Protein quality and microbiological changes in aerobically- or vacuum-packaged, irradiated fresh pork loins

The effect of gamma-irradiation on the physicochemical, organoleptic and microbiological properties of pork was studied, during 43 days of storage at 4±1°C. Irradiation treatments were carried out under air or vacuum packaging on fresh pork loins at a dose of 6 kGy, at two different dose rates: 2 kGy/h and 20 kGy/h. The loins were evaluated for protein sulphydryl content and emulsifying capacity, surface hydrophobicity of proteins and sensorial evaluation. Regardless of the type of packaging and dose rate of irradiation, all irradiated pork samples were effectively prevented from bacterial spoilage for at least 43 days. Meat redness and texture of irradiated loins were relatively well preserved during the storage period, especially when samples were stored under vacuum. Overall, the physicochemical and organoleptic changes in pork loins appeared to be relatively little affected by the 6 kGy dose. No marked changes in emulsifying capacity and protein sulphydryl content of proteins were noted throughout the storage period. However, the hydrophobicity was reduced (P?0.05) by the faster dose rate of irradiation and by longer storage.