The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Fikret Kargi - One of the best experts on this subject based on the ideXlab platform.
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effect of initial bacteria concentration on hydrogen gas production from cheese Whey Powder solution by thermophilic dark fermentation
Biotechnology Progress, 2012Co-Authors: Fikret Kargi, Nur Seza Eren, Serpil OzmihciAbstract:Dark fermentative hydrogen gas production from cheese Whey Powder solution was realized at 55°C. Experiments were performed at different initial biomass concentrations varying between 0.48 and 2.86 g L−1 with a constant initial substrate concentration of 26 ± 2 g total sugar (TS) per liter. The highest cumulative hydrogen evolution (633 mL, 30°C), hydrogen yield (1.56 mol H2 mol−1 glucose), and H2 formation rate (3.45 mL h−1) were obtained with 1.92 g L−1 biomass concentration. The specific H2 production rate decreased with increasing biomasss concentration from the highest value (47.7 mL g−1 h−1) at 0.48 g L−1 biomass concentration. Total volatile fatty acid concentration varied beetween 10 and 14 g L−1 with the highest level of 14.2 g L−1 at biomass concentration of 0.48 g L−1 and initial TS content of 28.4 g L−1. The experimental data were correlated with the Gompertz equation and the constants were determined. The most suitable initial biomass to substrate ratio yielding the highest H2 yield and formation rate was 0.082 g biomass per gram of TS. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 931–936, 2012
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bio hydrogen production from cheese Whey Powder cwp solution comparison of thermophilic and mesophilic dark fermentations
International Journal of Hydrogen Energy, 2012Co-Authors: Fikret Kargi, Nur Seza Eren, Serpil OzmihciAbstract:Abstract Cheese Whey Powder (CWP) solution was used as the raw material for hydrogen gas production by mesophilic (35 °C) and thermophilic (55 °C) dark fermentations at constant initial total sugar and bacteria concentrations. Thermophilic fermentation yielded higher cumulative hydrogen formation (CHF = 171 mL), higher hydrogen yield (111 mL H 2 g −1 total sugar), and higher hydrogen formation rate (3.46 mL H 2 L −1 h −1 ) as compared to mesophilic fermentation. CHF in both cases were correlated with the Gompertz equation and the constants were determined. Despite the longer lag phase, thermophilic fermentation yielded higher specific H 2 formation rate (2.10 mL H 2 g −1 cells h −1 ). Favorable results obtained in thermophilic fermentation were probably due to elimination of H 2 consuming bacteria at high temperatures and selection of fast hydrogen gas producers.
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hydrogen gas production from cheese Whey Powder cwp solution by thermophilic dark fermentation
International Journal of Hydrogen Energy, 2012Co-Authors: Fikret Kargi, Nur Seza Eren, Serpil OzmihciAbstract:Abstract Hydrogen gas production from cheese Whey Powder (CWP) solution by thermophilic dark fermentation was investigated at 55 °C. Experiments were performed at different initial total sugar concentrations varying between 5.2 and 28.5 g L−1 with a constant initial bacteria concentration of 1 g L−1. The highest cumulative hydrogen evolution (257 mL) was obtained with 20 g L−1 total sugar (substrate) concentration within 360 h while the highest H2 formation rate (2.55 mL h−1) and yield (1.03 mol H2 mol−1 glucose) were obtained at 5.2 and 9.5 g L−1 substrate concentrations, respectively. The specific H2 production rate (SHPR = 4.5 mL h−1 g−1cells) reached the highest level at 20 g L−1 total sugar concentration. Total volatile fatty acid (TVFA) concentration increased with increasing initial total sugar content and reached the highest level (14.15 g L−1) at 28.5 g L−1 initial substrate concentration. The experimental data was correlated with the Gompertz equation and the constants were determined. The optimum initial total sugar concentration was 20 g L−1 above which substrate and product (VFA) inhibitions were observed.
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fermentation of cheese Whey Powder solution to ethanol in a packed column bioreactor effects of feed sugar concentration
Journal of Chemical Technology & Biotechnology, 2009Co-Authors: Serpil Ozmihci, Fikret KargiAbstract:BACKGROUND: Cheese Whey Powder (CWP) is a concentrated source of lactose and other essential nutrients for ethanol fermentation. CWP solution containing different concentrations of total sugar was fermented to ethanol in an up-flow packed-column bioreactor (PCBR) at a constant hydraulic residence time (HRT) of 50 h. Total sugar concentration in the feed was varied between 50 and 200 g L -1 and a pure culture of Kluyveromyces marxianus was used for ethanol fermentation of lactose. Variations of ethanol and sugar concentrations with the height of the column and with the feed sugar concentration were determined. RESULTS: Ethanol concentration increased and total sugar decreased with the column height for all feed sugar contents. The highest effluent ethanol concentration (22.5 g L -1 ) and ethanol formation rate were obtained with feed sugar content of 100 g L -1 . Percentage sugar utilization decreased with increasing feed sugar content above 100 g L -1 yielding lower ethanol contents in the effluent. The highest ethanol yield coefficient (0.52 gE g -1 S) was obtained with a feed sugar content of 50 g L -1 . Biomass concentration also decreased with column height, yielding low ethanol formation in the upper section of the column. CONCLUSION: The packed column bioreactor was found to be effective for ethanol fermentation from CWP solution. The optimum feed sugar content maximizing the effluent ethanol and the specific rate of ethanol formation was found to be 100 g L -1 . High sugar content above 100 g L -1 resulted in low ethanol productivities due to high maintenance requirements.
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ethanol production from cheese Whey Powder solution in a packed column bioreactor at different hydraulic residence times
Biochemical Engineering Journal, 2008Co-Authors: Serpil Ozmihci, Fikret KargiAbstract:Cheese Whey Powder (CWP) solution containing 50 g L −1 total sugar was fermented to ethanol in a contin- uously operated packed column bioreactor (PCBR) using olive pits as support particles for cell attachment. Pure culture of Kluyveromyces marxianus (DSMZ 7239) was used in the PCBR for ethanol formation from lac- tose content of CWP solution. Sugar utilization and ethanol formation were investigated as function of the hydraulic residence time (HRT) between 17.6 and 64.4 h. Sugar concentration decreased with increasing ethanol concentration along the height of the column. Percent sugar utilization increased while effluent sugar concentration was decreasing with HRT between 17.6 and 50 h. Similarly, effluent ethanol con- centration increased while ethanol productivity was decreasing with increasing HRT up to 50 h. Further increases in HRT above 50 h resulted in decreases in effluent ethanol concentration. The ethanol yield coefficient also increased with increasing HRT and reached the highest level of 0.54 gE g −1 Sa t an HRT of 50 h. Due to cell settling to the bottom of the column, high fermentation rates were obtained in the lower section of the system. Therefore, the system can be operated with a height of 36 cm from the inlet to obtain high ethanol contents in the effluent with an HRT of 18 h.
Serpil Ozmihci - One of the best experts on this subject based on the ideXlab platform.
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effect of initial bacteria concentration on hydrogen gas production from cheese Whey Powder solution by thermophilic dark fermentation
Biotechnology Progress, 2012Co-Authors: Fikret Kargi, Nur Seza Eren, Serpil OzmihciAbstract:Dark fermentative hydrogen gas production from cheese Whey Powder solution was realized at 55°C. Experiments were performed at different initial biomass concentrations varying between 0.48 and 2.86 g L−1 with a constant initial substrate concentration of 26 ± 2 g total sugar (TS) per liter. The highest cumulative hydrogen evolution (633 mL, 30°C), hydrogen yield (1.56 mol H2 mol−1 glucose), and H2 formation rate (3.45 mL h−1) were obtained with 1.92 g L−1 biomass concentration. The specific H2 production rate decreased with increasing biomasss concentration from the highest value (47.7 mL g−1 h−1) at 0.48 g L−1 biomass concentration. Total volatile fatty acid concentration varied beetween 10 and 14 g L−1 with the highest level of 14.2 g L−1 at biomass concentration of 0.48 g L−1 and initial TS content of 28.4 g L−1. The experimental data were correlated with the Gompertz equation and the constants were determined. The most suitable initial biomass to substrate ratio yielding the highest H2 yield and formation rate was 0.082 g biomass per gram of TS. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 931–936, 2012
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bio hydrogen production from cheese Whey Powder cwp solution comparison of thermophilic and mesophilic dark fermentations
International Journal of Hydrogen Energy, 2012Co-Authors: Fikret Kargi, Nur Seza Eren, Serpil OzmihciAbstract:Abstract Cheese Whey Powder (CWP) solution was used as the raw material for hydrogen gas production by mesophilic (35 °C) and thermophilic (55 °C) dark fermentations at constant initial total sugar and bacteria concentrations. Thermophilic fermentation yielded higher cumulative hydrogen formation (CHF = 171 mL), higher hydrogen yield (111 mL H 2 g −1 total sugar), and higher hydrogen formation rate (3.46 mL H 2 L −1 h −1 ) as compared to mesophilic fermentation. CHF in both cases were correlated with the Gompertz equation and the constants were determined. Despite the longer lag phase, thermophilic fermentation yielded higher specific H 2 formation rate (2.10 mL H 2 g −1 cells h −1 ). Favorable results obtained in thermophilic fermentation were probably due to elimination of H 2 consuming bacteria at high temperatures and selection of fast hydrogen gas producers.
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hydrogen gas production from cheese Whey Powder cwp solution by thermophilic dark fermentation
International Journal of Hydrogen Energy, 2012Co-Authors: Fikret Kargi, Nur Seza Eren, Serpil OzmihciAbstract:Abstract Hydrogen gas production from cheese Whey Powder (CWP) solution by thermophilic dark fermentation was investigated at 55 °C. Experiments were performed at different initial total sugar concentrations varying between 5.2 and 28.5 g L−1 with a constant initial bacteria concentration of 1 g L−1. The highest cumulative hydrogen evolution (257 mL) was obtained with 20 g L−1 total sugar (substrate) concentration within 360 h while the highest H2 formation rate (2.55 mL h−1) and yield (1.03 mol H2 mol−1 glucose) were obtained at 5.2 and 9.5 g L−1 substrate concentrations, respectively. The specific H2 production rate (SHPR = 4.5 mL h−1 g−1cells) reached the highest level at 20 g L−1 total sugar concentration. Total volatile fatty acid (TVFA) concentration increased with increasing initial total sugar content and reached the highest level (14.15 g L−1) at 28.5 g L−1 initial substrate concentration. The experimental data was correlated with the Gompertz equation and the constants were determined. The optimum initial total sugar concentration was 20 g L−1 above which substrate and product (VFA) inhibitions were observed.
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fermentation of cheese Whey Powder solution to ethanol in a packed column bioreactor effects of feed sugar concentration
Journal of Chemical Technology & Biotechnology, 2009Co-Authors: Serpil Ozmihci, Fikret KargiAbstract:BACKGROUND: Cheese Whey Powder (CWP) is a concentrated source of lactose and other essential nutrients for ethanol fermentation. CWP solution containing different concentrations of total sugar was fermented to ethanol in an up-flow packed-column bioreactor (PCBR) at a constant hydraulic residence time (HRT) of 50 h. Total sugar concentration in the feed was varied between 50 and 200 g L -1 and a pure culture of Kluyveromyces marxianus was used for ethanol fermentation of lactose. Variations of ethanol and sugar concentrations with the height of the column and with the feed sugar concentration were determined. RESULTS: Ethanol concentration increased and total sugar decreased with the column height for all feed sugar contents. The highest effluent ethanol concentration (22.5 g L -1 ) and ethanol formation rate were obtained with feed sugar content of 100 g L -1 . Percentage sugar utilization decreased with increasing feed sugar content above 100 g L -1 yielding lower ethanol contents in the effluent. The highest ethanol yield coefficient (0.52 gE g -1 S) was obtained with a feed sugar content of 50 g L -1 . Biomass concentration also decreased with column height, yielding low ethanol formation in the upper section of the column. CONCLUSION: The packed column bioreactor was found to be effective for ethanol fermentation from CWP solution. The optimum feed sugar content maximizing the effluent ethanol and the specific rate of ethanol formation was found to be 100 g L -1 . High sugar content above 100 g L -1 resulted in low ethanol productivities due to high maintenance requirements.
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ethanol production from cheese Whey Powder solution in a packed column bioreactor at different hydraulic residence times
Biochemical Engineering Journal, 2008Co-Authors: Serpil Ozmihci, Fikret KargiAbstract:Cheese Whey Powder (CWP) solution containing 50 g L −1 total sugar was fermented to ethanol in a contin- uously operated packed column bioreactor (PCBR) using olive pits as support particles for cell attachment. Pure culture of Kluyveromyces marxianus (DSMZ 7239) was used in the PCBR for ethanol formation from lac- tose content of CWP solution. Sugar utilization and ethanol formation were investigated as function of the hydraulic residence time (HRT) between 17.6 and 64.4 h. Sugar concentration decreased with increasing ethanol concentration along the height of the column. Percent sugar utilization increased while effluent sugar concentration was decreasing with HRT between 17.6 and 50 h. Similarly, effluent ethanol con- centration increased while ethanol productivity was decreasing with increasing HRT up to 50 h. Further increases in HRT above 50 h resulted in decreases in effluent ethanol concentration. The ethanol yield coefficient also increased with increasing HRT and reached the highest level of 0.54 gE g −1 Sa t an HRT of 50 h. Due to cell settling to the bottom of the column, high fermentation rates were obtained in the lower section of the system. Therefore, the system can be operated with a height of 36 cm from the inlet to obtain high ethanol contents in the effluent with an HRT of 18 h.
Nur Seza Eren - One of the best experts on this subject based on the ideXlab platform.
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effect of initial bacteria concentration on hydrogen gas production from cheese Whey Powder solution by thermophilic dark fermentation
Biotechnology Progress, 2012Co-Authors: Fikret Kargi, Nur Seza Eren, Serpil OzmihciAbstract:Dark fermentative hydrogen gas production from cheese Whey Powder solution was realized at 55°C. Experiments were performed at different initial biomass concentrations varying between 0.48 and 2.86 g L−1 with a constant initial substrate concentration of 26 ± 2 g total sugar (TS) per liter. The highest cumulative hydrogen evolution (633 mL, 30°C), hydrogen yield (1.56 mol H2 mol−1 glucose), and H2 formation rate (3.45 mL h−1) were obtained with 1.92 g L−1 biomass concentration. The specific H2 production rate decreased with increasing biomasss concentration from the highest value (47.7 mL g−1 h−1) at 0.48 g L−1 biomass concentration. Total volatile fatty acid concentration varied beetween 10 and 14 g L−1 with the highest level of 14.2 g L−1 at biomass concentration of 0.48 g L−1 and initial TS content of 28.4 g L−1. The experimental data were correlated with the Gompertz equation and the constants were determined. The most suitable initial biomass to substrate ratio yielding the highest H2 yield and formation rate was 0.082 g biomass per gram of TS. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 931–936, 2012
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bio hydrogen production from cheese Whey Powder cwp solution comparison of thermophilic and mesophilic dark fermentations
International Journal of Hydrogen Energy, 2012Co-Authors: Fikret Kargi, Nur Seza Eren, Serpil OzmihciAbstract:Abstract Cheese Whey Powder (CWP) solution was used as the raw material for hydrogen gas production by mesophilic (35 °C) and thermophilic (55 °C) dark fermentations at constant initial total sugar and bacteria concentrations. Thermophilic fermentation yielded higher cumulative hydrogen formation (CHF = 171 mL), higher hydrogen yield (111 mL H 2 g −1 total sugar), and higher hydrogen formation rate (3.46 mL H 2 L −1 h −1 ) as compared to mesophilic fermentation. CHF in both cases were correlated with the Gompertz equation and the constants were determined. Despite the longer lag phase, thermophilic fermentation yielded higher specific H 2 formation rate (2.10 mL H 2 g −1 cells h −1 ). Favorable results obtained in thermophilic fermentation were probably due to elimination of H 2 consuming bacteria at high temperatures and selection of fast hydrogen gas producers.
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hydrogen gas production from cheese Whey Powder cwp solution by thermophilic dark fermentation
International Journal of Hydrogen Energy, 2012Co-Authors: Fikret Kargi, Nur Seza Eren, Serpil OzmihciAbstract:Abstract Hydrogen gas production from cheese Whey Powder (CWP) solution by thermophilic dark fermentation was investigated at 55 °C. Experiments were performed at different initial total sugar concentrations varying between 5.2 and 28.5 g L−1 with a constant initial bacteria concentration of 1 g L−1. The highest cumulative hydrogen evolution (257 mL) was obtained with 20 g L−1 total sugar (substrate) concentration within 360 h while the highest H2 formation rate (2.55 mL h−1) and yield (1.03 mol H2 mol−1 glucose) were obtained at 5.2 and 9.5 g L−1 substrate concentrations, respectively. The specific H2 production rate (SHPR = 4.5 mL h−1 g−1cells) reached the highest level at 20 g L−1 total sugar concentration. Total volatile fatty acid (TVFA) concentration increased with increasing initial total sugar content and reached the highest level (14.15 g L−1) at 28.5 g L−1 initial substrate concentration. The experimental data was correlated with the Gompertz equation and the constants were determined. The optimum initial total sugar concentration was 20 g L−1 above which substrate and product (VFA) inhibitions were observed.
Ihsan Bakirci - One of the best experts on this subject based on the ideXlab platform.
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Investigation of the use of Whey Powder and buttermilk Powder instead of skim milk Powder in yogurt production
Journal of Food Science and Technology, 2019Co-Authors: Neslihan Yıldız, Ihsan BakirciAbstract:The aim of this study was to determine some physical, chemical, microbiological and organoleptic properties of set-type yogurts made with six different skim milk Powder (SMP), Whey Powder (WP) and buttermilk Powder (BMP) during a 21-day period. Samples were taken from yogurts on day 1, 7, 14 and 21. Analyses were carried out on the total solids, fat, non-fat solids, protein, ash, viscosity, syneresis, pH, titratable acidity values. The counts of Streptococcus salivarius subsp. thermophilus, Lactobacillus delbrueckii subsp. bulgaricus and yeasts-molds were enumerated. Also, sensory evaluations were performed at the same times. The substitution effect of WP and BMP for SMP on ash, viscosity, syneresis and titratable acidity values of yogurts were found to be significant ( p
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Influence of inulin and demineralised Whey Powder addition on the organic acid profiles of probiotic yoghurts
International Journal of Dairy Technology, 2014Co-Authors: Arzu Kavaz, Ihsan BakirciAbstract:In this study, the effect of the different concentrations of inulin and demineralised Whey (d-Whey) Powder on the chemical characteristics and organic acid profiles of probiotic yoghurts were investigated. Analysis of chemical composition was performed on the first day, while pH and organic acid profiles were carried out during storage. The results indicated that different proportions of inulin and d-Whey Powder significantly influenced the levels of the organic acids, produced while the duration of storage affected the orotic, pyruvic, citric, lactic and acetic acid levels. There was a direct relationship between the level of d-Whey Powder and organic acid (except for butyric acid) concentration in the probiotic yoghurt.
Scott A. Rankin - One of the best experts on this subject based on the ideXlab platform.
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Short communication: Presence of galactose and glucose promotes browning of sweet Whey Powder.
Journal of Dairy Science, 2010Co-Authors: A. Dattatreya, Won-jae Lee, Scott A. RankinAbstract:This research examined the role of sugar type on the browning of sweet Whey Powder during accelerated storage. Two model systems, a lactose-lysine system and a sweet Whey Powder system, were selected. Within each model system experiment were samples containing equimolar concentrations of lactose, galactose, and glucose, and model systems were studied at 3 pH values: 6.5, 6.0, and 5.5. Samples were analyzed for changes in color after accelerated browning at 80 degrees C for 24 h. The results showed that the samples containing galactose and glucose browned to a greater degree than those containing lactose. Browning in the control and lactose-enriched samples was more susceptible to changes in pH. This study indicates that the processing conditions of liquid Whey in which the lactose monomers glucose and galactose accumulate may predispose SWP to brown more readily.
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Sweet Whey Powder Color
2008Co-Authors: Anupama Dattatreya, Scott A. RankinAbstract:Sweet Whey Powder (SWP) is used in many food applications due to its desirable nutritive and functional properties. During storage SWP may brown due to non-enzymatic Maillard-type reactions, thus reducing its nutritional and functional value. SWPs show considerable variation in the rate at which they brown. Commercial SWP were analyzed for pH, moisture content, water activity (a w ), extent of proteolysis, and browning precursor content. Several model systems were also evaluated. Samples were analyzed for color after accelerated storage. These studies demonstrate that acidic conditions, pH history and residual sugar composition in SWP increase browning. The browning extent depended on the main variables and several interactions. The chemistry of browning reactions under acidic conditions have been presented. Understanding SWP browning chemistry will aid in modifying the processing and handling conditions to obtain high quality Whey Powders stable to browning.
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Solvent type affects the number, distribution, and relative quantities of volatile compounds found in sweet Whey Powder.
Journal of Dairy Science, 2007Co-Authors: R.a. Prososki, M.r. Etzel, Scott A. RankinAbstract:This study compares the performance of diethyl ether, methylene chloride, methyl formate, and pentane in the analysis of volatile flavor components in sweet Whey Powder. Extracts were prepared from sweet Whey Powder using each solvent. Volatile components were isolated by solvent extraction followed by solvent-assisted flavor evaporation. Gas chromatography-mass spectroscopy, coelution with known standards, and retention indices were used to identify the volatile compounds. Sixty total compounds were either positively or tentatively identified across all 4 solvents, but the number, distribution between the molecular classes, and relative quantities detected depended on solvent type. The highest number, widest distribution, and greatest relative quantities were found using methylene chloride and methyl formate, whereas diethyl ether and especially pentane were noticeably less effective. Results are characterized using molecular-based characteristics of solvents and solutes including dipole moment, dielectric constant, Log P (octanol-water partition coefficient), polarizability, water solubility, and Lewis acidity/basicity. Polarity and acidity/basicity were the primary factors that determined solvent performance. This work establishes a molecular-level basis for the selection of solvents in the analysis of sweet Whey Powder flavors.
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kinetics of browning during accelerated storage of sweet Whey Powder and prediction of its shelf life
International Dairy Journal, 2007Co-Authors: Anupama Dattatreya, Mark R Etzel, Scott A. RankinAbstract:Abstract Sweet Whey Powder (SWP) of different pH was prepared by exposing native SWP to acetic acid vapors in a desiccator. Samples were subjected to accelerated browning at temperatures of 40, 60 and 80 °C in sealed vials and the rate of color formation was measured. Sample lightness decreased over time and the rate of decrease was faster at higher temperature and lower pH. Results were modeled using a pseudo-first-order reaction kinetic equation. The shelf life of SWP was estimated using a time–temperature plot. Increasing the temperature and decreasing the pH strongly decreased the shelf life from greater than 2 years at 53 °C for native SWP (pH∼6.3) to 5.2 days at 60 °C for intermediate acid SWP (pH∼5.0). A time–temperature–tolerance approach involving the practical storage life was used to predict the impact of temperature abuse during manufacture, transportation or storage.
