Showing papers in "Journal of Food Science in 1994"
TL;DR: In situ transesterification (ISTE) as discussed by the authors was used to determine overall fatty acid composition of foods by heating lipid-containing foods at 90°for 10 min after adding 0.5N NaOH in methanol for methanolysis and continued heating another 10 min for further methylation after adding 14% BF3 in methenol.
Abstract: Lipid extraction preceding fatty acid methyl esters (FAME) preparation for gas chromatography is time-consuming and cumbersome. We omitted the lipid extraction and performed in situ transesterification (ISTE) by heating lipid-containing foods at 90°for 10 min after adding 0.5N NaOH in methanol for methanolysis and continued heating another 10 min for further methylation after adding 14% BF3 in methanol. FAME prepared by ISTE showed fatty acid composition virtually identical to FAME prepared after lipid extraction from powder, liquid, phospholipid-rich, and tissue products. Due to its simplicity, speed, and reduced organic solvent usage, ISTE should be useful to determine overall fatty acid composition of foods.
493 citations
TL;DR: In this paper, fish protein hydrolysates were prepared using minced fillets and Al-calase and papain from raw herring and from herring defatted by ethanol extraction, cooking and pressing.
Abstract: Fish protein hydrolysates were prepared, using minced fillets and Al-calase and papain, from raw herring and from herring defatted by ethanol extraction, cooking and pressing. Physicochemical, sensory and storage properties as well as the molecular weight sizes in spraydried hydrolysates were evaluated. Fat extraction before hydrolysis reduced degree of hydrolysis. Alcalase hydrolyzed samples to a higher degree than papain. Ethanol extraction reduced fishy odor to barely detectable levels. Papain hydrolysates were more bitter than those made with Alcalase. Color and nonenzymic browning measurements indicated darkening during 3 mo storage at room temperature (∼20°C).
404 citations
TL;DR: In this paper, heat treatment, protein concentration, and pH effects on water vapor permeability (WVP) of plasticized whey protein films were examined, and the best film formation conditions were neutral pH, aqueous 10% (w/w) protein solutions heated for 30 min at 90°.
Abstract: Heat treatment, protein concentration, and pH effects on water vapor permeability (WVP) of plasticized whey protein films were examined. The best film formation conditions were neutral pH, aqueous 10% (w/w) protein solutions heated for 30 min at 90°. Isoelectric point adjustment of whey protein with calcium ascorbate buffer increased WVP with increasing buffer concentration, The importance of vacuum application to minimize film pore size was identified using scanning electron microscopy. Polyethylene glycol, glycerol and sorbitol plasticizer concentration affected film WVP. Determining the effects of relative humidity on WVP for plasticized whey protein films enabled prediction of film behavior under any water vapor partial pressure gradient.
387 citations
TL;DR: In this paper, the effects of functional protein additives on texture and colors were investigated using medium-grade Alaska pollock surimi and differential scanning calorimetry tests were applied to measure gel strength, gel deformability, and calcorimetric properties.
Abstract: Medium-grade Alaska pollock surimi was used to investigate the effects of functional protein additives on texture and colors. Torsion failure and differential scanning calorimetry tests were applied to measure gel strength, gel deformability, and calorimetric properties. CIE Lab color values were also measured. Shear stress values of gels and peak temperature of DSC thermograms were all increased. Shear strain, a good indicator of protein-protein interaction, was increased only by addition of egg white and beef plasma protein. Yellowness (b*) values were affected by all additives except frozen egg white. Whiteness index (L*-3b*) was a more effective indicator to differentiate additives.
279 citations
TL;DR: In this article, the effects of thermal processing on vitamin A and C retention in "jalapeno" peppers were determined by HPLC, and the results showed that thermal processing resulted in a 25% decrease of total provitamin A activity and a 75% decrease in total ascrobic acid.
Abstract: Alpha and beta carotene, provitamin A activity, dehydroascorbic acid, L-ascorbic acid and total ascorbic acid content of “jalapeno,”“bell,” long green/red “chile,”“serrano” and “yellow wax” peppers (Cupsicum annuum L.) at green and red stages of maturity were determined by HPLC. Effects of thermal processing on vitamin A and C retention in “jalapeno” peppers was also determined. Provitamin A activity ranged from 27.3 to 501.9 Retinol Equivalents (RE/100g). Ascorbic acid concentration ranged from 76.1 to 243.1 (mg/100g). Provitamin A activity and ascorbic acid content increased with maturity in all cultivars. Thermal processing of “jalapeno” cultivars resulted in a 25% decrease of total provitamin A activity and a 75% decrease in total ascrobic acid.
232 citations
TL;DR: In this paper, simple and acylated anthocyanins and other phenolics in ten cultivars and hybrids of low-bush and one cultivar of high-bush blueberries were extracted, isolated and quantified by reversed phase HPLC and capillary gas liquid chromatography.
Abstract: Simple and acylated anthocyanins and other phenolics in ten cultivars and hybrids of lowbush and one cultivar of highbush blueberries were extracted, isolated and quantified by reversed phase HPLC and capillary gas liquid chromatography. All cultivars contained nonacylated glucosides and galactosides of delphinidin, cyanidin, petunidin, peonidin, and malvidin. Each anthocyanin also occurred in the acetylated form in eight of eleven cultivars. Total anthocyanins in blueberries ranged from 110 to 260 mg/100g of fresh berries. ‘Blomidon’ berries contained the lowest and ‘Chignecto’ berries the highest level. Acetylated anthocyanins made up to 35% of the total anthocyanins in ‘Chignecto’. Chlorogenic acid was the major colorless phenolic of lowbush and highbush blueberries, at 50–100 mg/100 g fresh fruit.
226 citations
TL;DR: In this article, the effect of heat and enzymatic treatments on physical and moisture barrier properties of soy protein isolate (SPI) edible films were evaluated at three plasticizer levels.
Abstract: The effect of heat and enzymatic treatments on physical and moisture barrier properties of soy protein isolate (SPI) edible films were evaluated at three plasticizer levels. Heat treatment produced a film which was smoother and more transparent than unheated SPI films. Heated films had decreased water vapor permeability (WVP) and increased % elongation at break (%E) and % soluble protein when compared to unheated films. Treatment with horseradish peroxidase provided no further improvement in WVP, but increased tensile strength and % protein solubility and decreased %E. Enzymatic treatment caused protein degradation in addition to crosslinking.
208 citations
TL;DR: In this paper, the shelf life of minimally processed (peeled, deseeded, and diced) honeydew melon, kiwifruit, papaya, pineapple, and cantaloupe stored at 4°C was studied.
Abstract: Shelf life of minimally processed (peeled, deseeded, and diced) honeydew melon, kiwifruit, papaya, pineapple, and cantaloupe stored at 4°C was studied. Sensory assessments were carried out at 3-day intervals by highly trained panels until the end of shelf life. Microbiological counts were made immediately after dicing fruit and at the end of shelf life. Results indicated that both the length of shelf life and type of spoilage were related to fruit species. Minimally processed fruit had longer shelf life at 4°C than at temp. recommended for whole fruit when these were >4°C. Spoilage of 4°C-stored kiwifruit, papaya, and pineapple pieces was found to be not as a consequence of microbial growth
207 citations
TL;DR: In this paper, the effects of heating rate, storage temperature and water activity on surface caking and advanced caking of dairy-based infant formula powders were determined by the modified ampule and sealed glass test tube methods, respectively.
Abstract: The effects of heating rate, storage temperature and water activity on surface caking (Tsc) and advanced caking (Tac) of several dairy-based infant formula powders were determined by the modified ampule and sealed glass test tube methods, respectively. The glass transition temperature, Tg, was determined by differential scanning calorimetry. Observed Tsc and Tac values were higher at faster scan rates (5 and 10°C/min) compared to a slower heating rate (1°C/3 min). In addition, because of the sample size and the difference in viscous flow time constants, Tac≥ Tsc≥ Tg. As expected, stability towards collapse and sticking decreased with Increasing amounts of low-molecular-weight carbohydrate. The predicted stable storage water activities at room temperature based on Tsc were higher than those observed during storage; however, the water activity at which Tstarage= Tg gave a good prediction of the %RH when collapse begins.
202 citations
TL;DR: In this paper, the authors investigated the influence of gelling reaction conditions on the strength of protein gels prepared with microbial transglutaminase (TGase) in a micro well plate.
Abstract: Influence of gelling reaction conditions on the strength of several protein gels prepared with microbial transglutaminase (TGase) was investigated. A method was developed to gel proteins and measure gel breaking strength in a micro well plate. Enzyme concentration range for maximum gel breaking strength varied from 10 to 40 units/g protein. Maxima gel breaking strengths were achieved at 50°C for SPI, caseinate and gelatin and 65°C for egg yolk and egg white proteins. Optimum pH resulting in strong gels was pH 9 for SPI, caseinate, and egg yolk, and pH 6 for gelatin and egg white. Adjusting pH was promoted in egg white the formation of ɛ-(γ-glutamyl)lysine crosslinks and increased its gel breaking strength.
197 citations
TL;DR: In this article, tomatoes at breaker and pink stage maturities were coated with corn-zein film, which delayed color change and loss of firmness and weight during storage.
Abstract: Tomatoes at breaker and pink stage maturities were coated with corn-zein film. Color, weight and firmness changes and sensory quality were compared with noncoated tomatoes during storage at 21 o C. Corn-zein film delayed color change and loss of firmness and weight during storage. Shelf life was extended by 6 days with film coatings as determined by sensory evaluation
TL;DR: In this article, the effects of temperature and soluble solids on degradation of anthocyanins in sour cherry concentrate were determined over temperature ranges (-18 to 37)°and 50 to 80°C.
Abstract: The effects of temperature and soluble solids on degradation of anthocyanins in sour cherry concentrate were determined over temperature ranges (-18 to 37)°and 50 to 80°C. Anthocyanin degradation could be modeled as a first-order rate reaction, with rates of 33.97 × 10minus;3. hrminus;1 (15°CBrix), 59.19 × 10minus;3. hrminus;1 (45°CBrix) and 97.14 × 10minus;3. hrminus;1 (71°CBrix) at 80°C. Temperature dependence of reaction was described by the Arrhenius relationship. Activation energy for a solids content of 15-71°C Brix ranged from 16.37-19.14 kcal.moleminus;1 with an average of 17.45 kcal.moleminus;1
TL;DR: In this article, potato starch with anomalous stable (constant with time) paste viscosity has been proposed as a natural replacement for cross-linked starch, but its behavior and the influencing factors are not well understood.
Abstract: Potato starch with anomalous stable (constant with time) paste viscosity has been proposed as a natural replacement for cross-linked starch, but its behavior and the influencing factors are not well understood. Starch from 44 samples of potato tubers representing 34 genotypes was analyzed for phosphorus, mean granule diameter, amylose, calcium, magnesium, sodium, and potassium. Except for granule diameter, sodium, and potassium, each of those properties correlated significantly with one or more of five paste characteristics determined using the Brabender Visco-amylograph. Three samples had a stable viscosity in 1 yr of the study, but their behavior was not associated with unusual values of the other measured properties. The stable viscosity is probably a heritable trait influenced by cultural and climatic factors.
TL;DR: Purified Pacific whiting cathepsin L hydrolyzed myofibrils, myosin and native and heat-denatured collagen, and the degradation pattern of my ofibrils by the protease was the same as the autolytic pattern of surimi.
Abstract: Cathepsin B was the most active cysteine protease in Pacific whiting fish fillets; cathepsin L was predominant in surimi. Cathepsin L showed highest activity at 55°C in both fish fillets and surimi, indicating its function in myosin degradation during conventional heating of fillets and surimi, gels. Washing during surimi processing removed cathepsin B and H but not cathepsin L. Myosin heavy chain was the primary substrate during autolysis of surimi paste and actin and myosin light chain showed limited hydrolysis during 2 hr incubation. Purified Pacific whiting cathepsin L hydrolyzed myofibrils, myosin and native and heat-denatured collagen. The degradation pattern of myofibrils by the protease was the same as the autolytic pattern of surimi.
TL;DR: In this article, the effect of high pressure on bacteriostasis was studied using thermoduric spores of Bacillus stearothermophilus, and the synergistic effect of such high pressurization on the action of sucrose fatty acid ester was investigated.
Abstract: TO ESTABLISH a sterilization method with minimal heating, the effect of high pressure on bacteriostasis was studied using thermoduric spores of Bacillus stearothermophilus. After exposure to 800 MPa for 60 min at 60°C, the spore count decreased from 106 to 102/mL. However, exposure to the same pressure at room temperature did not cause significant change in spore numbers. The synergistic effect of high pressurization on the bacteriostatic action of sucrose fatty acid ester at low concentration (< 10 ppm) was pronounced with sucrose palmitic acid ester but not with sucrose stearic acid ester. Oscillatory pressurization was more effective for spore sterilization. Six cycles oscillation of 5-min pressurization with 400 MPa at 70°C decreased the spore count from 106 to 102/mL, and with 600 MPa, complete sterilization was achieved.
TL;DR: In this paper, high-pressure pretreated and frozen green beans, carrot dice or potato cubes were fluidized bed dried and compared to untreated, pressure-treated or water-blanched dried samples.
Abstract: High-pressure pretreated and frozen green beans, carrot dice or potato cubes were fluidized bed dried and compared to untreated, pressure-treated or water-blanched dried samples. Drying rates varied with pre-treatments. Freezing resulted in highest drying rates. Pressure-treated and water-blanched samples retained highly acceptable colors. Freezing or hot-water blanching or high-pressure pretreatment, followed by freezing, gave good rehydration. High-pressure treatment resulted in incomplete rehydration but combined with freezing, water uptake was between 2.1 and 4.8 mL/g. Retention of cell wall structures of frozen samples during drying was presumed responsible for more efficient mass transfer. Texture measurements revealed significant effects of pretreatments. Pressure-treated samples had texture nearest that of the raw material. No major differences in color were observed.
TL;DR: This paper found that low-fat frankfurters (10% fat, 12.5% protein) with olive, corn, sunflower or soybean oils had 67% lower total fat, 40-45% lower saturated fatty acids, 50-53% lower calories, reduced cholesterol and 20% higher protein.
Abstract: Low-fat frankfurters (10% fat, 12.5% protein) with olive, corn, sunflower or soybean oils, compared to control (29.1% animal fat, 10.4% protein) had 67% lower total fat, 40–45% lower saturated fatty acids, 50–53% lower calories, reduced cholesterol and 20% higher meat protein. Although they had darker red color they were 6–7.2% lower in processing yield and had higher purge accumulation, were firmer and less juicy. The type oil had no effect (P>0.05) on these characteristics but affected fatty acid composition. Frankfurters with olive oil had 41.8% higher monounsaturated fatty acids and those with seed oils 5–7 times higher polyunsaturated fatty acids. Soybean oil increased lin-olenic acid content and negatively affected overall acceptability and shelf-life.
TL;DR: The objective was to develop a method of sterilizing Bacillus stearothermophilus spores with minimal heating, and inactivation was achieved by spore destruction through six cycles of oscillatory pressurization at 70 o C and 600 MPa.
Abstract: Our objective was to develop a method of sterilizing Bacillus stearothermophilus spores with minimal heating. Inactivation was achieved by spore destruction through six cycles of oscillatory pressurization at 70 o C and 600 MPa, but inactivation was not complete within 60-min with continuous pressurization. Four pressurization cycles at 600 MPa and 5 min/cycle decreased the spore count from 10 6 to 10 2 /mL, and six cycles decreased the count from 10 6 to <10 0 . Spore inactivation was dependent on the adiabatic expansion velocity. On the other hand, protein denaturation by high pressures was due to phase changes of water under high pressure, and was not affected by adiabatic expansion velocity
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TL;DR: A chemically defined medium with glutamic acid as nitrogen source was devised for the culture of two species of Monascus (M. ruber and M. purpureus), resulting in optimum production of their pigments and their chemical structures (both free and complexed) were compared as discussed by the authors.
Abstract: A chemically defined medium with glutamic acid as nitrogen source was devised for the culture of two species of Monascus (M. ruber and M. purpureus), resulting in optimum production of their pigments and their chemical structures (both free and complexed) were compared. Structural data on two major complex pigments in aqueous solution were obtained by IR, UV, NMR and MS. They were free pigments linked to glutamic acid by amino groups, where nitrogen replaced the pyronoid oxygen.
TL;DR: In this paper, the physicochemical properties of legume starches were compared for physicochemical differences that may explain differences in functional properties, such as amylose, swelling power and solubility.
Abstract: Legume starches were compared for physicochemical properties that may explain differences in functional properties. Field pea starch had higher amylose, greater swelling power and solubility, and lower pasting temperatures than pinto and navy bean starches. Scanning electron microscopy (SEM) showed that field pea starch had larger, more irregularly shaped granules and more broken large granules than pinto or navy starches. The most starch damage was observed for field pea. Pinto and navy bean starches had greater resistance to swelling at 60 o C than field pea indicating a more strongly bonded micellar network. Nigher cold paste viscosity was observed for navy bean and field pea
TL;DR: Structural changes of actomyosin, the major protein of muscle, on heating have been estimated on ATPase activity using biophysical and biochemical techniques and fragmentation of actin filaments was observed, which was associated with the dissociation of myosin molecules.
Abstract: Structural changes of actomyosin, the major protein of muscle, on heating have been estimated on ATPase activity. We investigated carp actomyosin molecule changes on heating based on biophysical and biochemical techniques. Actomyosin molecules began to unfold at ∼30°C. Hydrophobic amino acid residues and SH groups, which had been inside the molecule, emerged to the surface. Because of hydrophobic interactions and disulfide bonds, actomyosin molecules formed aggregates. At > 40°C, a part of myosin molecules was dissociated from actin filaments. Thus, dissociated myosin and the myosin-lacking molecules co-existed. In addition, fragmentation of actin filaments was observed, which was associated with the dissociation of myosin molecules. At ≥ 60 °C actomyosin molecules formed larger aggregates, in which no filamentous shape was observed. This aggregation occurred mainly by formation of SS bonds.
TL;DR: P pH profiles of residual proteolytic and autolytic activities of uncooked surimi showed pH profiles similar to those of fish juice with a pH optimum of 5.5, confirming the validity of the assay for measuring activity.
Abstract: Commonly used protease assays and substrates were compared for sensitivity and simplicity in analyzing proteolytic activity in Pacific whiting causing gel weakening of surimi during heat-setting. Assay based on detection of trichloroacetic acid (TCA)-soluble products, using azocasein as substrate, showed highest sensitivity. By that assay, optimal pH of the protease was 5.5, and optimal temperature, 55 o C. The validity of the assay for measuring activity was confirmed by pH profiles of residual proteolytic and autolytic activities of uncooked surimi. These analyses showed pH profiles similar to those of fish juice with a pH optimum of 5.5
TL;DR: Unrefined pomace of three apple cultivars was dried, powdered, analyzed and evaluated in pie filling and oatmeal cookies as discussed by the authors, and both food products were rated as liked moderately.
Abstract: Unrefined pomace of three apple cultivars was dried, powdered, analyzed and evaluated in pie filling and oatmeal cookies. Pomace had 2.2 - 3.3% seed, 0.4 - 0.9% stem, 70.0 - 75.7% apple flesh and 20.1 - 26.4% rice hull as filtering aid (DWB). Average dietary fiber was 36.8% and remaining carbohydrates were 54.4%, totalling 91.2%. Remaining components were protein, fat and ash. Average pH was 4.3; water activity, 0.13; and WHC, 3.7 mL/g. Hunter color was L = 51.8, a = 5.4, and b = 18.2. Two levels of pomace in pie filling or three levels in oatmeal cookies did not affect color, cookie size or sensory scores. Both food products were rated as liked moderately.
TL;DR: In this paper, potato homogenate was refluxed with water for 30 min, yielding a total concentration of 48 mg/100 g for four phenolic acids (chlorogcnic, gallic, protocatechuic, and caffeic).
Abstract: Phenolics were extracted from potato peel waste using water or methanol. Phenolic acids in the extracts were quantified by HPLC. The greatest amounts of phenolic acids resulted when potato homogenate was refluxed with water for 30 min, yielding a total concentration of 48 mg/100 g. Four phenolic acids (chlorogcnic, gallic, protocatechuic, and caffeic) were characterized as major components. Aqueous extracts were stored 20 days and after 7 days at 25 o C exposed to light, chlorogenic acid had degraded to caffeic acid
TL;DR: In this paper, a 0.5% or 1% CaCl 2 treatment maintained firmness and reduced microbial growth of carrot shreds at all temperatures, and resulted in lower tissue pH than in the water-dipped controls.
Abstract: Carrot shreds, sticks and slices were dipped in solutions of CaCl 2 alone, or with chlorine and stored at 0, 5 or 10 o C to determine the effects of calcium (Ca) on storage quality. A 0.5% or 1% CaCl 2 treatment maintained firmness and reduced microbial growth of carrot shreds at all temperatures. These treatments also resulted in lower tissue pH than in the water-dipped controls. Treatments increased Ca content slightly in sticks and slices and substantially in shreds and had no effect on storage quality of sticks or slices
TL;DR: Aqueous extracts of potato peel waste were freeze-dried, high performance liquid chromatography (PLC) revealed that chlorogenic (50.31%), gallic (41.67%), protocatechuic (7.81%), andcaffeic (0.21%) acids were the major phenolics as discussed by the authors.
Abstract: Aqueous extracts of potato peel waste were freeze-dried, high performance liquid chromatography (PLC) of the freeze-dried extracts revealed that chlorogenic (50.31%), gallic (41.67%), protocatechuic (7.81%), andcaffeic (0.21%) acids were the major phenolics. During 15 days storage of the freeze-dried extract, no degradation of phenolics occurred. After 4 days storage at 63 o C, 5.00g of sunflower oil containing either the freeze-dried extract (200 ppm) or butylated hydroxyanisole (BHA) (200 ppm) reached peroxide values (PV) of 37.38 and 37.47 meq kg -1 respectively. L-ascorbic acid-6-palmitate was the best antioxidant (PV=10.65 meq kg -1 ) but the freeze-dried extract was as good as BHA
TL;DR: In this article, the authors developed an equation for calculating initial interfacial tension between a product and liquid, and found a power relationship between the initial tension and uptake of oil or other frying media.
Abstract: Fundamental theory of surface chemistry was utilized to develop an equation for calculating initial interfacial tension between a product and liquid. The relationship provides a practical approach to overcome the complexity of quantitatively determining interfacial tension of foods. The range of interfacial tension between a restructured potato product and the frying medium was 0.01 to 5.23–10−3 N/m. This range was determined using various frying media or additives. A power relationship was found between the initial interfacial tension and uptake of oil or other frying media. A model of capillary rise in porous media was implemented to explain the linear relationship between uptake and contact angle.
TL;DR: In this article, a review examines recent published suggestions that water dynamics may be applied instead of water activity determination to predict microbial stability of concentrated and intermediate moisture food systems, based on available experimental data.
Abstract: This review examines recent published suggestions that “water dynamics” may be applied instead of water activity (aw) determination to predict microbial stability of concentrated and intermediate moisture food systems. Factors such as the relative effectiveness of additives for antimicrobial stabilization through aw-lowering (i.e. glucose vs fructose, glycerol vs propylene glycol) and the importance of glass transition temperature as an indicator of microbial stability were examined, based on available experimental data. Determination of the glass-rubber transition characteristics and/or the use of the “water-dynamics” map does not enable prediction of the microbial stability of foods (i.e. inhibition of growth) with confidence. These were no more effective alternatives than the concept of water activity as a basis for predicting microbial growth in foods.
TL;DR: Fat in growth medium where Listeria monocytogenes cells were inoculated apparantly increased their resistance, and several methods may be useful for increasing inactivation rates.
Abstract: Listeria monocytogenes was inactivated by carbon dioxide at 35 and 45 o C under pressures of 70.3 and 210.9 μg/cm 2 . Inactivation rates were sensitive to temperature and pressure. Other factors such as pH, moisture content, and environmental conditions of cell growth also influenced the effectiveness of CO 2 treatment. Bacteria were more difficult to inactivate when they were suspended in the medium with fat or oil, which may have protected the cells from penetration by CO 2 . Fat in growth medium where Listeria monocytogenes cells were inoculated apparantly increased their resistance. Several methods may be useful for increasing inactivation rates
TL;DR: In this article, the effects of temperature, lactic acid (or pH), sodium chloride, and sodium nitrite on the non-thermal inactivation of a three strain mixture of Listeria monocytogenes were examined in brain heart infusion broth.
Abstract: The effects of temperature, lactic acid (or pH), sodium chloride, and sodium nitrite on the non-thermal inactivation of a three strain mixture of Listeria monocytogenes were examined in brain heart infusion broth. A total of 249 survivor curves representing 157 combinations of the four variables were generated. The survivor curves were described mathematically by fitting data using linear and nonlinear primary models. Supplemental studies demonstrated that (1) preculturing the microorganism in an acidic environment or in media containing glucose increased acid tolerance, (2) survivor curve tailing was not due to the presence of a more resistant subpopulation, and (3) the rate of non-thermal inactivation was independent of initial population density. Response surface models were developed for predicting the effects and interactions of the four independent variables on the inactivation of Listeria monocytogenes under adverse environmental conditions.