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.     

Activity of caffeic acid in different fish lipid matrices: A review

Caffeic acid, a hydroxycinnamic acid common in different vegetable sources, has been employed as a natural antioxidant for inhibiting oxidation of fish lipids present in different food matrices. The aim of this review is to discuss the mechanisms involved in the antioxidative and prooxidative effects of caffeic acid found in different model systems containing fish lipids. These model systems include bulk fish oils, liposomes from cod roe phospholipids, fish oil emulsions, washed cod mince, regular horse mackerel mince and a fish oil fortified fitness bar. The data reported show that the antioxidant activity depends on the physical state of the lipids and the composition of the intrinsic matrix in which they are situated. Caffeic acid significantly prevented rancidity in both unwashed and washed fish mince, the latter which was fortified with haemoglobin. In the unwashed mince, the activity was however clearly dependent on the lipid to antioxidant ratio. In these systems, an important redox cycle between caffeic acid and the endogenous reducing agents ascorbic acid and tocopherol were further thought to play an important role for the protective effects. The effect of caffeic acid was also highly dependent on the storage temperature, showing higher effectiveness above than below 0 °C. Caffeic acid was not able to inhibit oxidation of bulk fish oils, fish oil in water emulsions and the fish-oil enriched fitness bar. In the liposome system, caffeic acid inhibited haemoglobin (Hb)-promoted oxidation but strongly mediated Fe²⁺ mediated oxidation. In conclusion, caffeic acid can significantly prevent Hb-mediated oxidation in fish muscle foods but its activity in food emulsions and liposomes is highly dependent on the pH, the emulsifier used and the prooxidants present.     

Antioxidant Properties of Caffeic acid Phenethyl Ester and 4‐Vinylcatechol in Stripped Soybean Oil

Caffeic acid was used to synthesize 4‐vinylcatechol (4‐VC) by thermal decarboxylation and to prepare caffeic acid phenethyl ester (CAPE) by esterification reaction. The identities of synthesized products were confirmed by ¹H NMR. Antioxidative activities of 4‐VC and CAPE were compared with α‐tocopherol and BHT in stripped soybean oil at 60 °C under the dark. To evaluate the degrees of oxidation at different concentrations and combinations, peroxide value (PV) and ¹H NMR were performed. From the results of PV, the formation of primary oxidation products (i.e., hydroperoxides) in stripped soybean oil containing 200 ppm CAPE was the slowest. The relative oxidation degree of 200 ppm CAPE (9.5%) was lower than other samples on 9 d. Similar results were obtained by ¹H NMR analysis. After 15 d of storage, levels of conjugated diene forms and aldehydes of 200 ppm CAPE sample (57.3 and 0.9 mmol/mol oil) were also lower than other treatments. In addition, 4‐VC and α‐tocopherol were found to have a synergistic antioxidant effect.     

Oxidation of lipid and protein in horse mackerel (Trachurus trachurus) mince and washed minces during processing and storage

Protein and lipid oxidation was followed during processing and storage of mince and washed minces prepared from horse mackerel (Trachurus trachurus). Briefly horse mackerel mince (M0) was washed with three volumes of water, mimicking the surimi production and different washed products were obtained: M1, M2 and M3, with one, two and three washing steps, respectively. The different products were characterised (i.e. lipid content, protein, water, iron, fatty acid profile and tocopherol content) and analysed for protein and lipid oxidation in order to investigate the impact of the washing steps on oxidation. Subsequently the different products were stored for up to 96 h at 5 °C and samples were taken out regularly for analysis. Lipid oxidation was investigated by measuring primary oxidation products (lipid hydroperoxides) and secondary oxidation products (volatiles). Protein oxidation was followed by determination of protein solubility, protein thiol groups and protein carbonyl groups using colorimetric methods as well as western blotting for protein carbonyl groups. Lipid and protein oxidation markers indicated that both lipid and protein oxidation took place during processing and the ranking for oxidation was as follows M0 < M1 < M2 ? M3 with M0 being significantly less oxidised than M3. Results indicated that washing creates an imbalance in the initial prooxidant-antioxidant equilibrium in the muscle tissue and contributes to the observed differences in the oxidative status of the four products obtained. In contrast, during storage of different products, lipid oxidation development was faster in M0 and the ranking was as follows M0 > M1 > M2 ? M3. Lipid and protein oxidation developed simultaneously in different minces during storage, but it was not possible to determine at which level these two reactions were coupled.     

Effect of Kiam (Cotylelobium lanceolatum Craib) Wood Extract on the Haemoglobin-Mediated Lipid Oxidation of Washed Asian Sea Bass Mince

Introduction

Effect of ethanolic kiam wood extract (EKWE; 12 0.05% and 0.1%, w/w) on the retardation of haemoglobin-mediated lipid oxidation of washed Asian sea bass mince added without and with menhaden oil stored in ice up to 10 days was investigated.

Results and discussion

Samples containing haemoglobin had the highest peroxide value (PV) within the first 8 days and possessed the greater amount of thiobarbituric acid-reactive substances (TBARS), compared to those added with no haemoglobin (P?<?0.05), regardless of 5% menhaden oil addition. Incorporation of 5% (v/w) menhaden oil to the washed mince had no impact on the formation of PV and TBARS, compared with oil-free samples during the storage (P?>?0.05). With addition of EKWE, lipid oxidation in washed mince added with haemoglobin and menhaden oil was retarded, especially when the higher level (0.1%; w/w) was used, as evidenced by lowered PV and TBARS. Formation of volatile lipid oxidation compounds was retarded in the sample containing oil and haemoglobin and treated with 0.1% EKWE, compared with that without the addition of EKWE after 10 days of storage in ice (P?<?0.05).

Conclusion

Sensory analysis revealed that samples containing haemoglobin without and with oil added had the highest intensity of fishy odour, compared to those treated with EKWE (0.05% and 0.1%) and the control sample (washed mince; P?<?0.05). Thus, EKWE, especially at a level of 0.1%, could serve as a potential natural antioxidant in prevention of lipid oxidation and retardation of development of fishy odour and volatile lipid oxidation compounds in washed mince during iced storage.     

Novel interactions of caffeic acid with different hemoglobins: Effects on discoloration and lipid oxidation in different washed muscles

Caffeic acid (CA) accelerated methemoglobin (Hb) formation at pH 5.8 and 25 °C. This was attributed to electron donation from CA to liganded O₂ in Hb. CA inhibited hemin dissociation from metHb. Pig Hb remained mostly as oxyHb and did not promote lipid oxidation in washed cod muscle (WCM) nor washed turkey muscle (WTM) during iced storage at pH 5.8. Conversely, perch Hb rapidly was converted to metHb and readily promoted lipid oxidation based on lipid peroxide and hexanal formation. CA strongly inhibited perch Hb-mediated lipid oxidation during storage. Once metHb formation occurred in WCM, CA appeared to maintain the heme protein as metHb during the remainder of iced storage. CA may have become bound to perch Hb based on filtration analysis. CA facilitated the transfer of perch Hb (but not pig Hb) from the aqueous phase to the insoluble components of WCM. Collectively, these results suggest that CA inhibited Hb-mediated lipid oxidation by various mechanisms not related to inhibition of metHb formation.     

Development of lipid oxidation during manufacturing of horse mackerel surimi

When fatty fish are transformed into surimi, lipid oxidation takes place, decreasing the quality of the product. This study was aimed to identify the critical stages of the process in terms of the development of lipid oxidation. Horse mackerels were transformed into surimi on a pilot line and samples taken (hand‐skinned fillets = minced fillets, mince, washed and refined minces, paste, surimi and washing water). Most of the lipids were removed during the process and neutral lipids were lost in higher proportion than polar lipids. As a consequence, total lipids of surimi contained more polyunsaturated fatty acids (338 ± 19 g kg^?1) than total lipids of the minced fillets (220 ± 8 g kg^?1). Thiobarbituric acid reactive substances (TBARS) was higher in the minced fillets than in the mince because less subcutaneous fat and dark muscle were removed during hand‐mincing, indicating that the settings of the skinning–deboning machine can strongly influence the final quality of the product. Concentrations of lipid oxidation products increased significantly during the next stages of surimi processing. The increase was more pronounced for TBARS than hydroperoxides. Concentrations in hydroperoxides were similar in mince and washed mince (15.3 ± 2.8 and 16.6 ± 2.8 mmoles kg^?1 lipid) and increased in refined mince (29.6 ± 2.8 mmoles kg^?1 lipid). TBARS accounted for 2.7 ± 1.0 mg kg^?1 lipid in mince, 40.4 ± 2.3 mg kg^?1 lipid in washed mince and 237 ± 7 mg kg^?1 lipid in refined mince. Hydroperoxides and TBARS were found in appreciable amounts in washing water (76.9 ± 4.7 mmoles kg^?1 lipid and 479 ± 8 mg kg^?1 lipid respectively), when they decreased in surimi (27.3 ± 3.8 mmoles kg^?1 lipid and 44.2 ± 0.8 mg kg^?1 lipid respectively) compared with refined mince. This shows that the last dewatering stage is crucial to ensure surimi quality. Copyright © 2005 Society of Chemical Industry     

Change in α‐tocopherol contents,lipid oxidation and fatty acid profile in eggs enriched with linolenic acid or very long‐chain ω3 polyunsaturated fatty acids after different processing methods

The influences of dietary supplementation with α‐tocopheryl acetate (α‐TA) and of processing (by hard‐boiling and scrambling) of eggs enriched with ω3 fatty acids, either very long‐chain ω3 polyunsaturated fatty acids (VLC ω3 PUFAs) or linolenic acid (LNA), on fatty acid composition, α‐tocopherol content and lipid oxidation (thiobarbituric acid (TBA) values) were studied. Four dietary treatments were formulated from a basal diet containing 40 g kg^?1 linseed oil (LO) or fish oil (FO) combined with either 0 or 100 mg α‐TA kg^?1 of feed. Eggs from LO treatments were enriched with LNA and those from FO treatments were rich in VLC ω3 PUFAs. Neither processing nor dietary supplementation with α‐TA modified greatly the fatty acid profile of eggs. Dietary supplementation with α‐TA increased the α‐tocopherol content of eggs (187.2 versus 407.9 µg g^?1 dry matter). Eggs from FO treatments showed lower α‐tocopherol content than those from LO treatments (273.5 versus 321.6 µg g^?1 dry matter), and processing of eggs enriched with VLC ω3 PUFA reduced the α‐tocopherol content by a significant 16%. Moreover, processing of eggs increased lipid oxidation two‐ to nine‐fold. Oxidation levels of hard‐boiled eggs were 30.4% higher than those of scrambled eggs. TBA values in hard‐boiled and scrambled eggs were significantly reduced when 100 mg α‐TA kg^?1 of feed supplemented the diet only in those eggs enriched with VLC ω3 PUFA (from FO treatments). Copyright © 2003 Society of Chemical Industry     

Influences of potassium ferrocyanide on lipid oxidation of salted cod (Gadus morhua) during processing, storage and rehydration

The effects of added potassium ferrocyanide (CN) in different concentrations (2.5 ppm, 7.5 ppm and 100 ppm), in salt, on lipid oxidation in cod during salting, storage and rehydration were examined in this study. An increase in CN concentration accelerated lipid oxidation of the salted cod, as observed by increases in lipid hydroperoxides (PV) and thiobarbituric acid-reactive substances (TBARS), as well as in the development of fluorescence compounds (δF_or and δF_aq). A yellow discolouration (higher b^∗ value) of salted cod was associated with higher levels of oxidation derivatives. High correlation between PV, TBARS and free fatty acid (FFA), as well as between FFA and δF_or, was found. The results of principal component analysis showed that TBARS, b^∗ value and δF_or were the strongest indicators of lipid oxidation during salting and storage.     

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).     

Antioxidative Properties and Ability of Phenolic Compounds of Myrtus communis Leaves to Counteract In Vitro LDL and Phospholipid Aqueous Dispersion Oxidation

Antioxidant activities of Myrtus communis leaf phenolic compounds (McPCs) were investigated on 2,2′‐9‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS⁺?) and oxygen radical absorbance capacity (ORAC) tests or on oxidation of biological models, human low‐density lipoprotein (LDL) and phospholipid aqueous dispersion (l ‐α‐phosphatidylcholine stabilized by bile salts). Two extraction techniques, microwave‐assisted (MAE) and conventional (CE), were used to isolate McPCs, producing similar results of phenolic compound content. ABTS⁺? assay showed clearly that myrtle extracts exhibited a stronger scavenging effect than butylated hydroxyanisole and α‐tocopherol, with a slight advantage for myrtle CE extract. In ORAC assay, the both McPC extracts were similarly less effective than the pure compounds as caffeic acid and myricitrin (myricetin 3‐O‐rhamnoside) but stronger than butylated hydroxytoluene. Moreover, myrtle CE and MAE extracts, and myricitrin were able to inhibit similarly the production of conjugated dienes and to prolong the lag phase (Tlag) during Cu²⁺‐induced LDL oxidation with a dose‐response effect. The cryo‐electron microscopy observations on studied phospholipid dispersion stabilized by bile salts (BS) revealed the presence of bilayer vesicles and micelles. In 2,2′‐azobis (2‐amidinopropane) hydrochloride–induced phospholipid/BS oxidation, myrtle CE and MAE extracts gave similar effects to α‐tocopherol and caffeic acid but myricitrin showed a higher protective effect than myrtle extracts. We showed also that no synergic or additive effect between α‐tocopherol and myrtle extracts or caffeic acid in α‐tocopherol–enriched phospholipid/BS dispersion, but myricitrin showed an additive effect and thus promoted the total antioxidant activity. These data showed that myrtle extract could be used as potential natural antioxidants, food stabilizers, or natural health products.     

EFFECTS OF USING ROSEMARY EXTRACT AND ONION JUICE ON OXIDATIVE STABILITY OF SARDINE (SARDINA PILCHARDUS) MINCE

Sardine (Sardina pilchardus) mince was treated with rosemary extract (RE – 300 ppm) and onion juice (OJ – 1 mL/100 g) then stored at ?20C for 5 months. Proximate composition, thiobarbutiric acid (TBA), free fatty acids (FFA) and peroxide value (PV) were determined on 0 and 15 days and 1, 2, 3, 4 and 5 months of storage. Fatty acid composition was also determined on 0 and 5 months of frozen storage. TBA, PV and FFA levels increased on all experimental groups due to the lipid oxidation. RE showed antioxidative effect on sardine mince during frozen storage as indicated by TBA, PV and FFA levels. Oxidation was delayed for 3 months by OJ treatment. At the end of 5 months’ storage, the TBA values in OJ treatment and control (C) treatment were out of consumable limits. After frozen storage of 5 months polyunsaturated fatty acid level decreased and saturated fatty acid level increased in the control treatment. No significant change was observed in fatty acid composition in samples of RE and OJ treatments.     

Resonance Raman monitoring of lipid oxidation in muscle foods

A non‐invasive optical method, Resonance Raman spectroscopy was used to follow the progression of lipid oxidation in mechanically separated turkey (MST) through oxidative bleaching of β‐carotene. Endogenous or 20–50 ppm exogenously added β‐carotene in MST served as an inert marker of lipid oxidation, and the corresponding detectable Raman signals were highly correlated with the concentration of lipid oxidation products in muscle tissue based on thiobarbituric acid reactive substances (TBARS). Adding 100 ppm β‐carotene accelerated lipid oxidation in MST, and thus should not be used. No carotenoid Raman response was obtained for washed cod with added hemoglobin, which indicates that washed cod was devoid of any endogenous β‐carotene. Moreover, the absence of any heme protein Raman response eliminates the use of heme as an alternative biomarker to β‐carotene at the excitation wavelength employed. These studies indicate that resonance Raman detection of endogenous or exogenous β‐carotene can be used as a simple and non‐invasive method for assessing lipid oxidation status in finely comminuted muscle tissues.     

Effect of plant phenolics,tocopherol and ascorbic acid on oxidative stability of pork patties

BACKGROUND: There is great interest in the use of naturally occurring antioxidants to delay oxidation in meat products. The effect of rosemary extract (RE), green tea extract (TE), tocopherol, trolox, ascorbic acid (AA) and ascorbyl palmitate (AP), at levels of 50–200 ppm of antioxidant components, on colour (CIE L*a*b*), lipid (TBARS) and protein oxidation (thiol groups) in fresh, frozen and cooked pork patties during illuminated chill storage was investigated. Individual components of RE and TE were also tested. RESULTS: RE, TE, AP, tocopherol and trolox equally inhibited lipid oxidation in fresh and frozen patties, whereas for cooked patties RE was most effective. AA stimulated lipid oxidation. No dose effect in the range of 50–200 ppm was found for fresh and frozen patties, whereas for cooked patties higher doses of RE and TE more efficiently prevented lipid oxidation. Protein oxidation was hardly influenced by antioxidant treatment. Colour stability decreased as follows: tocopherol, AA and AP > RE and TE > trolox. Antioxidant properties of the extracts and their major antioxidant components were comparable. CONCLUSION: The relative effect of the antioxidants depends on the oxidation parameter assessed, the applied dose and the hydrophilic/lipophilic character. Copyright © 2009 Society of Chemical Industry     

Changes in Electrophoretic Patterns of Gadoid and Non-gadoid Fish Muscle during Frozen Storage

Sodium dodecyl sulfate polyacrylamidc gel electrophoresis of fish muscle during frozen storage showed that a crosslinked protein of 280,000 daltons formed with gadoids, whereas this band did not occur with non-gadoid fish species. For cod, 20 days at -7°C are needed for the crosslink to appear, whereas for whiting only 3 days arc needed. Formaldehyde (FA) may be responsible for the crosslinking. Adding ascorbic acid to cod mince prior to freezing accelerated dimcthylamine and FA formation during frozen storage and accelerated the formation of the crosslinked protein, while leaving cod fillets on ice for 10 days prior to freezing, reduced the Instron hardness and the crosslinked protein did not appear with 50 days of frozen storage at -7°C.     

Antioxidants from barley husks impregnated in films of low-density polyethylene and their effect over lipid deterioration of frozen cod (Gadus morhua)

BACKGROUND: The changes in quality of cod fillets packaged in films with and without antioxidants during 12 months of frozen storage at ? 20 °C were investigated in the present study. The following parameters were determined in order to study lipid hydrolysis and primary and secondary lipid oxidation in the samples during frozen storage: peroxide value, conjugated dienes, conjugated triene hydroperoxides, free fatty acids, totox value, thiobarbituric acid‐reactive substances and p‐anisidine value. RESULTS: Films containing antioxidants isolated from barley husks were effective in slowing down lipid hydrolysis and primary and secondary lipid oxidation processes. Secondary lipid oxidation reached maximum values in the 12th month of storage in control samples and samples packaged with antioxidant‐containing film. Maximum lipid hydrolysis and lipid oxidation values for control cod samples were significantly higher than the maximum values found in samples packaged with antioxidant‐containing film. CONCLUSION: The results confirm the efficacy of natural antioxidants derived from barley husks in slowing down lipid hydrolysis and increasing the oxidative stability of cod flesh. They also demonstrate the potential usefulness of natural antioxidants extracted from barley husks in the development of active packaging films for food preservation. Copyright © 2011 Society of Chemical Industry     

Influence of storage time and temperature on lipid deterioration during cod (Gadus morhua) and haddock (Melanogrammus aeglefinus) frozen storage

Lean fish deterioration during frozen storage (−30 and −10 °C) for up to 1 year was studied by the assessment of lipid changes. Comparison between a formaldehyde (FA)-forming species (cod) and a non-FA-forming one (haddock) was carried out. Lipid damages were measured on the basis of free fatty acids (FFA), peroxide value (PV), thiobarbituric acid index (TBA-i) and fluorescent compounds. In both species at −30 °C, most lipid damage indices showed significant correlations with the storage time. However, at −10 °C, only the FFA and fluorescence detections provided significant correlations with the storage time. Comparison between the fish species showed higher lipid oxidation (PV and TBA-i) and hydrolysis (FFA content) in haddock than in cod at −10 °C; however, a higher fluorescence development was observed in cod at the same temperature. At −30 °C, little differences in lipid damage indices were detected between the two species. © 1999 Society of Chemical Industry     

HYDROXYL RADICAL MODIFICATION OF FISH MUSCLE PROTEINS

A xanthine oxidase-based system was used to generate hydroxyl free radicals in washed, minced cod muscle. Oxidation of protein was measured by increase in protein carbonyl content; the system used produced approximately 0.1 mol of carbonyl groups per 10⁵ g of protein. This degree of oxidation had only minor effects on the SDS-PAGE patterns of the muscle proteins. The solubility of the proteins was not affected by this amount of oxidation unless they were also subjected to a freeze/thaw cycle. With a freeze/thaw cycle, a highly significant decrease in protein solubility occurred compared to that which took place in a sample not exposed to the free radical system. Lowering the pH from 6.8 or 6.5 to 6.0 or 5.5 had a strong negative impact on protein solubility. Protein oxidation appeared in two phases in washed cod mince, an initial rapid increase followed by a second phase that may have been linked to oxidation of the small amount of lipid in the sample. Comparison of protein carbonyl formation in stored mackerel fillets or mince indicated that the range of oxidation studied in the cod model system was similar to what occurs in stored mackerel muscle postmortem.     

Antioxidant Activity of Whey in a Salmon Oil Emulsion

The antioxidant capabilities of whey in a Tween 20^TM‐stabilized salmon emulsion were investigated. Whey fractions inhibited formation of thiobarbituric acid reactive substances (TBARS) and lipid peroxides in a 10 % salmon oil emulsion in the order of whey > high‐molecular‐weight (HMW) fraction > low‐molecular‐weight fraction. Heating the HMW fraction exposed sulfhydryls, with optimum exposure at 80 °C. Heating the HMW fraction above 80 °C increased antioxidant activity. The HMW fraction of whey (80 °C) alone, α‐tocopherol (40 ppm) alone, and their combination inhibited TBARS 59,19 and 86%, respectively, at 21 d of storage. Sulfhydryls oxidized before a‐tocopherol, suggesting that sulfhydryls are the primary antioxidant. Results indicate that whey proteins could be useful antioxidants in food emulsions.     

Effect of dietary supplementation with vitamin E on characteristics of vacuum‐packed lamb

The effect of dietary vitamin E supplementation on lamb during vacuum‐packed storage was studied. Thirty‐six weaned male Manchego breed lambs were offered four dietary treatments (20, 270, 520 and 1020 mg vitamin E kg^?1 feed). Lambs were fed the vitamin E‐supplemented diet from 13 until 26 kg live weight. Pieces of M. longissimus dorsi were stored under vacuum at 2 ± 1 °C in the dark and meat quality was assessed after 5, 14 and 28 days of storage. Dietary supplementation significantly increased the α‐tocopherol concentration in the muscle (P < 0.001). Initially, lipid oxidation, meat colour and bacterial load were similar in all groups. In meat of non‐supplemented lambs the thiobarbituric acid reactive substance value increased throughout storage, whereas in meat of supplemented lambs it did not increase. Meat pigments and discolouration proportion were significantly affected by storage time (P < 0.001). The bacterial load was low initially, but after 28 days of storage it was close to 7 log₁₀ colony‐forming units (cfu) cm^?2 and Enterobacteriaceae surpassed the limit of acceptability of 2.5 log₁₀ cfu cm^?2, making the lamb unsuitable for human consumption. Meat of supplemented lambs displayed less lipid oxidation than that of their non‐supplemented counterparts, while meat colour and bacterial load were not affected by supplementation. Copyright © 2007 Society of Chemical Industry