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At least 19 recordsLinked to original sources
PubMed2000

Lack of specificity of trans,trans-muconic acid as a benzene biomarker after ingestion of sorbic acid-preserved foods.

The benzene metabolite, trans,trans-muconic acid (MA), has been shown to be a sensitive and specific biomarker for ambient benzene exposure levels as low as approximately 0.5 ppm. However, at lower exposure levels, the use of MA as a benzene biomarker is complicated by the fact that it is also a metabolite of the food preservative, sorbic acid. To better assess the extent of this interference, MA was measured in sequential spot urine samples over a 2-day study period from eight volunteers (four adults and two parent-children pairs) who consumed two sorbic acid-preserved foods. Large increases in MA concentration were seen after ingestion of both foods. Individual peaks ranged as high as 1673.7 ng/ml (705.3 ng/mg creatinine) in adults and 1752.1 ng/mg creatinine (1221.3 ng/ml) in children. Ratios of peak to baseline values varied from 2.5 to 60. The average peak in the seven subjects who showed an increase in MA after ingestion of the first sorbic acid-containing food was 531.1 ng/ml (693.2 ng/mg creatinine). The average in the seven participants who ingested the second food was 1102.1 ng/ml (795.3 ng/mg creatinine). Twenty-four-hour personal air benzene levels were all low (< or = 5.6 ppb). Substantial variation in MA results were seen in some males related to creatinine adjustment. These data indicate that sorbic acid-preserved foods have the potential to cause substantial interference with MA as a biomarker for both occupational and environmental benzene exposure in populations, such as in the United States, where consumption of preserved foods is common. Development of methods to minimize and/or assess sorbic acid interference will improve MA specificity in such populations.

Adult↗
PubMed1995

[Food preservation through combined processes].

Food preservation by combined processes is based on the combination of two or more existing preservation methods with the objective of developing milder preservation procedures. Currently two combined processes (CP) deserve a special attention, the preservation of food by high pressures (HP) and the preservation of food with the combined use of heat and ultrasounds under pressure (Mano-Thermo-Sonication). In the preservation by HP, the food, at room temperature or at very mild temperature, is held during relatively long periods under very high pressures (100-1000 MPa) to inactivate its enzymes and/or microorganisms. This procedure has proved to be effective to inactivate vegetative cells but much less effective to inactivate most enzymes and bacterial spores. Several kinds of food preserved by this method have already been launched into the market. In Mano-Thermo-Sonication (MTS Process) microorganisms and enzymes are inactivated by a combined heat/ultrasounds treatment under pressure. By this method, the lethality of heat treatments at the same temperature is highly increased. Therefore, the intensity of heat treatments can be drastically reduced. Heat resistance of spores is reduced by a factor of 1/10 and that of enzymes and vegetative cells is reduced by a factor of 1/50 approximately. The applicability of this procedure is currently being investigated.

Food Handling↗
PubMed1956

[Preserved foods].

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Food Preservation↗
PubMed1956

[Preserved foods].

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Food Preservation↗
PubMed2000

Basic aspects of food preservation by hurdle technology.

Hurdle technology is used in industrialized as well as in developing countries for the gentle but effective preservation of foods. Previously hurdle technology, i.e., a combination of preservation methods, was used empirically without much knowledge of the governing principles. Since about 20 years the intelligent application of hurdle technology became more prevalent, because the principles of major preservative factors for foods (e.g., temperature, pH, a(w), Eh, competitive flora), and their interactions, became better known. Recently, the influence of food preservation methods on the physiology and behaviour of microorganisms in foods, i.e. their homeostasis, metabolic exhaustion, stress reactions, are taken into account, and the novel concept of multitarget food preservation emerged. In the present contribution a brief introduction is given on the potential hurdles for foods, the hurdle effect, and the hurdle technology. However, emphasis is placed on the homeostasis, metabolic exhaustion, and stress reactions of microorganisms related to hurdle technology, and the prospects of the future goal of a multitarget preservation of foods.

Bacteria↗
PubMed1995

Bacteriocins: modes of action and potentials in food preservation and control of food poisoning.

Lactic acid bacteria (LAB) play an essential role in the majority of food fermentations, and a wide variety of strains are routinely employed as starter cultures in the manufacture of dairy, meat, vegetable and bakery products. One of the most important contributions of these microorganisms is the extended shelf life of the fermented product by comparison to that of the raw substrate. Growth of spoilage and pathogenic bacteria in these foods is inhibited due to competition for nutrients and the presence of starter-derived inhibitors such as lactic acid, hydrogen peroxide and bacteriocins (Ray and Daeschel, 1992). Bacteriocins, are a heterogenous group of anti-bacterial proteins that vary in spectrum of activity, mode of action, molecular weight, genetic origin and biochemical properties. Currently, artificial chemical preservatives are employed to limit the number of microorganisms capable of growing within foods, but increasing consumer awareness of potential health risks associated with some of these substances has led researchers to examine the possibility of using bacteriocins produced by LAB as biopreservatives. The major classes of bacteriocins produced by LAB include: (I) lantibiotics, (II) small heat stable peptides, (III) large heat labile proteins, and (IV) complex proteins whose activity requires the association of carbohydrate or lipid moieties (Klaenhammer, 1993). Significantly however, the inhibitory activity of these substances is confined to Gram-positive bacteria and inhibition of Gram-negatives by these bacteriocins has not been demonstrated, an observation which can be explained by a detailed analysis and comparison of the composition of Gram-positive and Gram-negative bacterial cell walls (Fig. 1). In both types the cytoplasmic membrane which forms the border between the cytoplasm and the external environment, is surrounded by a layer of peptidoglycan which is significantly thinner in Gram-negative bacteria than in Gram-positive bacteria. Gram-negative bacteria possess an additional layer, the so-called outer membrane which is composed of phospholipids, proteins and lipopolysaccharides (LPS), and this membrane is impermeable to most molecules. Nevertheless, the presence of porins in this layer will allow the free diffusion of molecules with a molecular mass below 600 Da. The smallest bacteriocins produced by lactic acid bacteria are approximately 3 kDa and are thus too large to reach their target, the cytoplasmic membrane (Klaenhammer, 1993; Stiles and Hastings, 1991). However, Stevens et al. (1991) and Ray (1993) have demonstrated that Salmonella species and other Gram-negative bacteria become sensitive to nisin after exposure to treatments that change the permeability barrier properties of the outer membrane (see below). This review will focus on the mode of action of lantibiotics (class I) and class II LAB bacteriocins and their potentials in food preservation and control of food poisoning.

Bacteriocins↗