Grete Bertelsen

Spices as antioxidants

Synthetic antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) have been used widely for many years to retard lipid oxidation. Concern about the safety of synthetic antioxidants together with consumer preference for natural products has resulted in increased research on natural antioxidants. Many spices have been shown to impart an antioxidative effect in foods. This article summarizes the literature on the antioxidative effects of spices. The term spice is defined as dry plant material that is normally added to food to impart flavour.

Potential of biobased materials for food packaging

Abstract During the last decade, joint efforts by the packaging and the food industries have reduced the amount of food packaging materials. Nonetheless, used packaging materials are still very visible to the consumer in the context of disposal. Environmental issues are becoming increasingly important to the European consumer. Consequently, consumer pressure may trigger the use of biobased packaging materials as an alternative to materials produced from non-renewable resources. Biologically based packaging is defined as packaging containing raw materials originating from agricultural sources, i. e. produced from renewable, biological raw materials such as starch and bioderived monomers. These materials are not necessarily biodegradable. Consequently, this review is not limited to biodegradable packaging. To date, biodegradable packaging has commanded great attention, and numerous projects are under way in this field. One important reason for this attention is the marketing of environmentally friendly packaging materials. Furthermore, use of biodegradable packaging materials has the greatest potential in countries where landfill is the main waste management tool. Biobased packaging materials include both edible films and edible coatings along with primary and secondary packaging materials. Excellent in-depth reviews on edible films and coatings are already available 1 , 2 , 3 . Therefore, this review focuses on biobased primary packaging materials for foods. Several concerns must be addressed prior to commercial use of biobased primary food packaging materials. These concerns include degradation rates under various conditions, changes in mechanical properties during storage, potential for microbial growth, and release of harmful compounds into the packaged food product. Furthermore, the biopackaging must function as food packaging and meet the requirements of the individual food product. This review evaluates the suitability of biobased packaging for foods. Additionally, it identifies the challenges involved when using biobased packaging for different foods.

Production and applications of biobased packaging materials for the food industry.

Materials based on renewable resources are being developed at an increasing rate. Today, the only biobased food-packaging materials used commercially on a major scale are based on cellulose. However, materials based on proteins, starch, polylactate and other renewable resources may be the food-packaging materials of tomorrow. The paper presents some of the different biobased materials and their potential as foodpackaging materials.

Colour stability and lipid oxidation of fresh beef. Development of a response surface model for predicting the effects of temperature, storage time, and modified atmosphere composition.

Samples of fresh beef muscles (Longissimus dorsi) were packed under varying modified atmosphere conditions (20-80% oxygen) and stored at 2-8°C for 10 days. At 2 day intervals meat samples were analysed for surface colour and extent of lipid oxidation (TBARS). Response surface models for predicting the effects of temperature, storage time and modified atmosphere composition on colour stability and lipid oxidation were developed. Temperature and time were found to be the most important factors for retaining meat colour and minimizing lipid oxidation. However, the oxygen content also had a significant effect on both quality parameters. A stable interval of maintaining a good meat colour was found between 55 and 80% O(2). Response surface modelling was found to be very promising for modelling of chemical quality changes in meat stored under different conditions, but the large biological differences between animals may complicate the development of generally valid models.

Dietary vitamin E: Quality and storage stability of pork and poultry

Lipid oxidation is one of the primary processes of quality deterioration in meat and meat products. The changes in quality are manifested by adverse changes in flavour, colour, texture, and nutritive value and by the possible production of toxic compounds. Dietary supplementation of vitamin E above requirement levels has been found to be effective in reducing lipid oxidation in meat and meat products. This review focuses on the deposition and antioxidative effects of muscle vitamin E and how supra-nutritional vitamin E supplementation influences lipid oxidation, colour, water-holding capacity and cholesterol oxidation in pig and poultry meat. Furthermore, the interactions between muscle vitamin E with processing, packaging and storage conditions are taken into consideration.

The antioxidative activity of plant extracts in cooked pork patties as evaluated by descriptive sensory profiling and chemical analysis

Antioxidative efficiency of extracts of rosemary, green tea, coffee and grape skin in precooked pork patties was investigated during storage under retail conditions (10 days, 4 °C, atmospheric air), using descriptive sensory profiling following reheating and quantitative measurements of hexanal, thiobarbituric acid reactive substances (TBARS) and vitamin E as indicators of lipid oxidation. The initial oxidative status of pork patties (evaluated by ANOVA) showed a significant lower level of secondary oxidation products and higher levels of vitamin E in patties with extracts incorporated, indicating that the extracts retarded lipid oxidation during processing of the meat. Data analysis for the storage study was based on qualitative overview of sensory/chemical variation by principal component analysis (PCA) and quantitative ANOVA-PLSR for determination of the relationship between design variables (days of chill-storage, extract treatment) versus sensory-chemical variables and PLSR for elucidating the predictive ability of the chemical methods for sensory terms. Lipid oxidation was seen to involve a decrease in perception of meat flavour/odour and a concomitant increase in the off-flavour/odours linseed, rancid. TBARS, hexanal and vitamin E were all significant predictive indices (P<0.05) for the majority of the sensory terms, while vitamin E through negative correlation with TBARS and hexanal displayed its antioxidative effect and thus, its ability to preserve sensory fresh meat flavour/odour. The effect of the various extracts incorporated in the product was clearly related to the degree of lipid oxidation and an overall ranking of the antioxidative efficiency of extracts in declining order became apparent: Rosemary>Grape skin>Tea>Coffee>Reference. Furthermore, the relation between extracts and vitamin E indicated that the extracts, to some extent, interacted with the vitamin and prevented it from degrading. In conclusion, the rosemary extract displayed potential for maintaining sensory eating quality in processed pork products.

Screening of antioxidative activity of spices. A comparison between assays based on ESR spin trapping and electrochemical measurement of oxygen consumption

Abstract Spices belonging to the Labiatae family were used to develop assays for evaluation of antioxidative activity of spices and spice extracts. Two different principles for detection of antioxidative activity were used: (i) an ESR spin trapping technique in which hydroxyl radicals were generated by the Fenton reaction and trapped by 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) in competition with spice extract constituents, (ii) electrochemical measurement of oxygen depletion rate in a heterogeneous lipid/water emulsion with lipid oxidation initiated by metmyoglobin. The ESR free radical method relates to the effect of antioxidant on the initiation of oxidation, while the oxygen depletion method relates to the effect of antioxidant on the propagation of oxidation. For both methods, marjoram and basil showed the lowest activity, while winter savory showed the highest activity as measured by the ESR method, and Turkish oregano and Chilean oregano showed the highest activity as measured by the oxygen depletion method. Total phenol content in the extract correlates linearly with the antioxidant activity as measured by oxygen depletion, but not with the free radical scavenging effect. It is concluded that extracts of the investigated spices contain components with at least two different antioxidative mechanisms.

The antioxidative activity of summer savory (Satureja hortemis L.) and rosemary (Rosmarinus officinalis L.) in dressing stored exposed to light or in darkness

Abstract For an oil-in-water emulsion dressing, addition of 0.15% of dried leaves of summer savory (Satureja hortensis L.) or more significantly of rosemary (Rosmarinus officinalis L.), resulted in a significantly better antioxidative protection than addition of 80 ppm propyl gallate (standard concentration for this type of product) during dark storage at 19 °C for up to 24 weeks, as determined by development of conjugated dienes, peroxide value, head space hexanal and thiobarbituric acid-reactive substances. Addition of freeze-dried methanol extract of the two spices, in an equivalent concentration, had less antioxidative effect, but was comparable to the effect of propyl gallate. Exposure to fluorescent light (850 lux) during storage had a clear pro-oxidative effect for dressing with or without spice or spice extract added, when compared to dark storage. For dressing with extract of savory added, the antioxidative effect found for dark storage was during light exposure, changed to a pro-oxidative effect, and a hexanal level as high as 600 mg kg−1 oil was detected after 8 weeks of storage, while the net antioxidative effect of rosemary was maintained for storage exposed to light.

Effect of pre-slaughter physiological conditions on the oxidative stability of colour and lipid during chill storage of pork.

The physiological condition of the live animal was found to significantly affect colour, lipid oxidation and water holding capacity of chill stored pork chops (M. Longissimus dorsi) in a study, where various pre-slaughter conditions were achieved by the following four treatments: (A) control; (B) subjected to treadmill exercise immediately prior to stunning; (C) given epinephrine injection 15 h prior to slaughter; and (D) given epinephrine injection 15 h before slaughter and further subjected to treadmill exercise immediately before stunning. The treatments resulted in variations in energy metabolites (glycogen, lactate, creatine phosphate, ATP) and ultimate pH (pH(u)), with the lowest pH(u) in chops from treatments A and B, and in significantly different tristimulus colour L(∗)-, a(∗)- and b(∗)-parameters, although the effect of treatment on colour was not consistent during the chill storage period of 6 days. Overall, chops from treatments A and B had significantly higher L(∗)- and b(∗)-values (were paler and less blue) than chops from C and D during storage under conditions typical for retail trade. The initial a(∗)-values were higher (redder) in chops from treatments A and B, but the colour, as judged by the a(∗)-values, was less stable in meat from these treatments compared with treatments C and D. Lipid oxidation, evaluated by thiobarbituric acid reactive substances (TBARS) in the fresh meat, and drip loss, measured after 6 days of storage, were both significantly higher in chops from treatments A and B compared to chops obtained from treatments C and D. Statistical analysis relating the pH and the level of various energy metabolites post-mortem in the individual animals to the measured quality parameters, revealed that pH(u) was the most important factor affecting product quality. In conclusion, over all product quality depends on obtaining a pH(u) in the narrow range where both meat quality parameters such as colour, lipid oxidation and drip loss as well as microbiological aspects have to be considered.

Influence of the oxidative quality of dietary oil on broiler meat storage stability.

Broilers were fed a high fat diet containing 11% oil (9% rapeseed oil, 2% soya bean oil) and the oil was given either as fresh (peroxide value of 1 meqv. O(2)kg(-1) oil) or as highly oxidised (peroxide value of 156 meqv. O(2)kg(-1) oil). Diets were supplemented with 46 mg all-rac-α-tocopheryl acetate kg(-1) diet, resulting in a tocopherol content of 80.8 mg α-tocopherol and 58.6 mg γ-tocopherol per kg diet in the fresh oil diet and of 44.0 mg α-tocopherol and 18.3 mg γ-tocopherol per kg diet in the oxidised oil diet, respectively, reflecting the degradation of the natural occurring tocopherols in the oxidised diet. Only minor differences were seen with respect to fatty acid composition in muscles from birds fed the two diets. The oxidation of the dietary oil lowered lipid stability significantly (p < 0.01) in both raw and precooked meats during chill storage, whereas only minor effects on the stability of frozen meat were seen. Tocopherol levels were significantly lower (p < 0.01) in muscles from birds fed the oxidised oil diet, explaining the decreased lipid stability of meat from these birds. Thigh meat was more susceptible to lipid oxidation during storage than breast meat, regardless of dietary treatment, although thigh meat had markedly higher tocopherol levels than breast meat. The molar ratio of PUFA > 18:2 (polyunsaturated fatty acids with three or more double bonds) to α-tocopherol was significantly (p < 0.01) higher in thigh meat compared with breast meat, explaining the lower stability of the former during storage.