scholarly journals EFFECT OF CHEMICAL AND THERMAL TREATMENTS ON INHIBITION OF PEROXIDASE ACTIVITIE OF PURPLE SKIN EGGPLANT (SOLANUMMELONGENA L.)

2021 ◽  
Vol 9 (04) ◽  
pp. 304-313
Author(s):  
Jocelyn Constant Yapi ◽  
◽  
Jean Bedel Fagbohoun ◽  
Zranseu Ange Benedicte Deffan ◽  
Elvis Gbocho Serge Ekissi ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Inactivation ◽  
Solanum Melongena ◽  
Thermal Treatments ◽  
Optimal Temperature ◽  
Spectrophotometric Methods ◽  
Acid Effect ◽  
Fresh Cut ◽  
D Values ◽  
Increasing Temperature

Peroxidase (POD) associated with the browning of fresh-cut fruits and vegetableswas extracted from purple skin eggplant(Solanum melongena L.) and characterised using reliable spectrophotometric methods. Maximal POD activity was found at 35 °C and pH 6.0 with guaiacol as the substrate. The enzyme was stable at his optimal temperature (35 °C) and hisat pH stability was in the range of 5.6 - 6.6.Peroxidase retained its full activity in the presence of ion K+, Cu2+, Na+, Pb2+ and Ba2+ but were inhibited strongly by the ion Fe2+ and Mg2+ and the reducing agents as sodium thiosulfateand ascorbic acid. Effect of heattreatment on eggplant peroxidase showed that D-values decreased with increasing temperature, indicating faster peroxidase inactivation at higher temperatures.At 60 °C, the D-values ranged from 20.42 to 54.24 min. Hence, heat treatment at 60 °C for 30 min reduced browning of eggplant fruit.These data can be used to predict prevention of browning in the purple skin eggplantby thermal inactivation and the use of chimical agents onthe enzyme.

Thermal Inactivation of Listeria monocytogenes in Chicken Gravy

1992 ◽  
Vol 55 (7) ◽  
pp. 492-496 ◽  
Author(s):  
I-PING D. HUANG ◽  
AHMED E. YOUSEF ◽  
ELMER H. MARTH ◽  
M. EILEEN MATTHEWS
Keyword(s):  
Heat Treatment ◽  
Listeria Monocytogenes ◽  
Heat Resistance ◽  
Thermal Inactivation ◽  
Refrigerated Storage ◽  
Department Of Agriculture ◽  
Large Numbers ◽  
Z Value ◽  
D Values ◽  
The U.S

Heat resistance of Listeria monocytogenes strains V7 and Scott A in chicken gravy and changes in heat resistance during refrigerated storage were studied. After chicken gravy was made, it was cooled to 40°C, inoculated with 105 CFU L. monocytogenes per ml of gravy, and then stored at 7°C for 10 d. Gravy was heated at 50, 55, 60, and 65°C immediately after inoculation and after 1, 3, 5, and 10 d of refrigerated storage. The D values for strains Scott A and V7 in gravy heated at 50°C at day 0 were 119 and 195 min and at day 10 they were 115 and 119 min, respectively, whereas at 65°C comparable values at day 0 were 0.48 and 0.19 min and at day 10 they were 0.014 and 0.007 min. Heat resistance (expressed as D values) was greater at day 0 than at the end of refrigerated storage. The z values ranged from 3.41 to 6.10°C and were highest at the early stages of chill storage and then decreased at the later stages. Strain V7 was more heat resistant than Scott A at 50°C. Strain Scott A always had a higher z value than did strain V7 at the same storage interval. A heat treatment greater than the 4-D process recommended by the U.S. Department of Agriculture was required to inactivate the large numbers of L. monocytogenes that developed in chicken gravy during refrigerated storage.

Saccharomyces cerevisiae Thermal Inactivation Kinetics Combined with Ultrasound

1999 ◽  
Vol 62 (10) ◽  
pp. 1215-1217 ◽  
Author(s):  
A. LÓPEZ-MALO ◽  
S. GUERRERO ◽  
S. M. ALZAMORA
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Thermal Inactivation ◽  
Order Reaction ◽  
Heat Inactivation ◽  
Inactivation Kinetics ◽  
Thermal Treatments ◽  
Combined Treatments ◽  
First Order ◽  
D Values ◽  
Kinetics Of

Inactivation kinetics of Saccharomyces cerevisiae during thermal treatments at moderate temperatures (45.0, 47.5, 50.0, 52.5, or 55.0°C) combined with application of 20 kHz of ultrasound were evaluated. S. cerevisiae inactivation under the combined effects of heat and ultrasound followed first-order reaction kinetics, with decimal reduction times (D) that varied from 22.3 to 0.8 min. D values in treatments that combined heat and ultrasound were significantly smaller (P < 0.05) than D values obtained for thermal treatments and were more noticeable at temperatures below 50°C. The dependence of the D value on temperature had a significantly (P < 0.05) greater z value for combined treatments. Yeast heat inactivation kinetics revealed decreased thermal resistance caused by ultrasound.

scholarly journals Inactivation Kinetics and Thermodynamics Parameters of Polyphenol Oxidase and Peroxidase Activities in an Extract from of Violet Eggplant (Solanum melongena L.)

2021 ◽  
pp. 83-92
Author(s):  
Jocelyn Constant Yapi ◽  
Gbocho Serge Elvis Ekissi ◽  
Kouame Claude Ya ◽  
Patrice Lucien Kouamé
Keyword(s):  
Polyphenol Oxidase ◽  
Thermal Inactivation ◽  
Solanum Melongena ◽  
Inactivation Kinetics ◽  
Kinetic Properties ◽  
Thermostable Enzymes ◽  
Polyphenol Oxidases ◽  
Thermodynamics Parameters ◽  
Z Value ◽  
Increasing Temperature

Enzymatic browning is associated with the action of polyphenol oxidases (PPO) and peroxidases (POD). The products of these enzymes cause undesirable changes of color and flavor of processed eggplant products. The present study aimed to evaluate kinetic properties and thermodynamics parameters of PPO and POD activities for controlling this undesirable process in extract from of violet eggplant. The effect of heat treatment on polyphenol oxidase and peroxidase activities in violet eggplant were studied over a range of 30 to 80 °C. T1/2-values of enzymatic activities are between 6.15 ± 0.03 and 13,27 ± 0,04 min at 80 °C, they decreased with increasing temperature, indicating a difference thermostability of each enzyme. D- and k-values decreased and increased, respectively, with increasing temperature, indicating faster of these enzymes inactivation at higher temperatures. Results suggested that polyphenol oxydase and peroxidase were relatively thermostable enzymes with a Z-value which from 50.25 and from 88.33 °C and Ea of 41.21 and of 27.78 kJmol-1. Thermodynamic parameters were also calculated. The Gibbs free energy ΔG values range from 43.24 ± 0,03 to 91.45 ± 0,01 kJ/mol. These kinetic data can be used to predict prevention of browning in the violet eggplant (Solanum melongena L.) by thermal inactivation of enzymes.

scholarly journals Physicochemical Characterization and Effect of Thermal Treatments on the Enzymatic Browning Inhibition of Violet Eggplant (Solanum melongena L.) Cultivated in Daloa (Côte d’Ivoire)

2021 ◽  
pp. 69-78
Author(s):  
Yapi Jocelyn Constant ◽  
Deffan Zranseu Ange Bénédicte ◽  
Fagbohoun Jean Bedel ◽  
Kouame Lucien Patrice
Keyword(s):  
Fruits And Vegetables ◽  
Physicochemical Characterization ◽  
Solanum Melongena ◽  
Physicochemical Characteristics ◽  
Enzymatic Browning ◽  
Thermal Treatments ◽  
Negative Effects ◽  
Polyphenol Oxidases ◽  
Browning Inhibition ◽  
D Values

Background: The polyphenol oxidase (PPO) responsible for the enzymatic browning of fruits and vegetables, has been involved in the undesirable brown discolouration of food products that resulted in negative effects on colour, taste, and nutritional value. This is a generally undesired process and needs to be prevented in food technology. Objective: The present work was carried out to evaluate the effect of chemical and thermal treatments on browning inhibition of eggplant fruit (Solanum melongena L.). Materials and Methods: A screening of PPOs activities from eggplant was carried out. The physicochemical characteristics and thermal stability of main PPOs activities were determined in order to develop methods of anti-browning. Results: Dopamine oxidase and pyrocatechol oxidase activities were the most active main eggplant fruit PPO activities. Maximal PPO activity was found at 30°C, pH 7.0 for dopamine and 25°C, pH 6.6 for pyrocatechol. The enzymes were stable and retained almost all of their catalytic activity at their optimum temperature (30 and 25°C) for 120 min and their pH stability was in the range of 5.0 - 7.0. Polyphenol oxidases (dopamine oxidase and pyrocatechol oxidase) remained their full activity in the presence of ion Na+, Cu2+, Pb2+ (1 mM) but were inhibited strongly by the ion Fe2+ and Pb2+ (5 mM). On the other hand, the ion K+, Ba2+ and chemical agents, EDTA, citric acid have virtually no effect on dopamine oxidase and pyrocatechol oxidase activities. Energy for inactivation (Ea) obtained using dopamine and pyrocatechol were 30.8 kJ/mol and 7.1 kJ/mol from respective substrates. Conclusion: Ascorbic acid was a better inhibitor where 82.32% of PPOs inhibition was achieved. At 65°C, their D-values ranged from 44.72 to 72.72 min. Hence, heat treatment at 65°C for 30 min reduced browning of eggplant fruit. These data regarding the properties of PPO should enhance understanding of the browning reaction in eggplant and lead to the development of techniques for controlling this undesirable process.

Development of Thermal Surrogate Microorganisms in Ground Beef for In-Plant Critical Control Point Validation Studies

2007 ◽  
Vol 70 (4) ◽  
pp. 952-957 ◽  
Author(s):  
LI MA ◽  
JEFFREY L. KORNACKI ◽  
GUODONG ZHANG ◽  
CHIA-MIN LIN ◽  
MICHAEL P. DOYLE
Keyword(s):  
Validation Studies ◽  
Thermal Inactivation ◽  
Control Point ◽  
Ground Beef ◽  
Thermal Treatments ◽  
Pediococcus Acidilactici ◽  
Food Grade ◽  
Critical Control Point ◽  
D Values ◽  
Salmonella Senftenberg

In search of a suitable surrogate microorganism for in-plant critical control point validation, we compared the rates of thermal inactivation of three bacteria, Enterococcus faecium B2354, Pediococcus parvulus HP, and Pediococcus acidilactici LP, to those of Listeria monocytogenes and Salmonella. Ground beef samples containing 4 and 12% fat were inoculated with E. faecium, L. monocytogenes, and Salmonella Senftenberg 775W and heated at 58, 62, 65, or 68°C. The decimal reduction times (D-values) for E. faecium B2354 in 4 and 12% fat ground beef were 4.4 to 17.7 and 3.6 to 14.6 times greater, respectively, than those for L. monocytogenes or Salmonella Senftenberg 775W at all temperatures tested, with the greatest differences in D-values occurring at 58 and 62°C. Higher fat content protected bacteria from thermal inactivation in general, especially at temperatures lower than 68°C. The heat resistance in a broth medium at 62°C of two food-grade bacteria, P. parvulus HP and P. acidilactici LP, was compared with that of the three strains under study. The D-values of P. parvulus HP and P. acidilactici LP were lower than those of E. faecium B2354 but 4.1 and 2.5 times greater, respectively, than those of Salmonella Senftenberg 775W, the most resistant pathogen. These results indicate that thermal treatments of ground beef at 58 to 68°C that kill E. faecium B2354 will also kill Salmonella and L. monocytogenes, and the two Pediococcus isolates may serve as alternate surrogates for validation studies when a less heat-resistant surrogate is desired. However, additional studies in ground beef are needed with the Pediococcus strains in the desired temperature range intended for validation purposes.

scholarly journals Study on browning mechanism of fresh-cut eggplant (Solanum melongena L.) based on metabolomics, enzymatic assays and gene expression

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Xiaohui Liu ◽  
Aidong Zhang ◽  
Jing Shang ◽  
Zongwen Zhu ◽  
Ye Li ◽  
...  
Keyword(s):  
Gene Expression ◽  
Fruits And Vegetables ◽  
Solanum Melongena ◽  
Downward Trend ◽  
Glutathione Metabolism ◽  
Phenylpropanoid Metabolism ◽  
Kegg Pathways ◽  
Maximum Value ◽  
Cut Time ◽  
Fresh Cut

AbstractEnzymatic browning is one of the crucial problems compromising the flavor and texture of fresh-cut fruit and vegetables. In this study, an untargeted metabolomics approach based on liquid chromatography-mass spectrometry (LC–MS) was used to explore the browning mechanism in fresh-cut eggplant. Metabolomics studies showed that with the increase of fresh-cut time, the contents of 946 metabolites changed dynamically. The metabolites having the same trend share common metabolic pathways. As an important browning substrate, the content of chlorogenic acid increased significantly, suggesting that may be more important to fresh-cut eggplant browning; all 119 common differential metabolites in 5 min/CK and 3 min/CK contrastive groups were mapped onto 31 KEGG pathways including phenylpropanol metabolism, glutathione metabolism pathway, et al. In physiological experiments, results showed that the Phenylpropanoid-Metabolism-Related enzymes (PAL, C4H, 4CL) were changed after fresh-cut treatment, the activities of three enzymes increased first and then decreased, and reached the maximum value at 5 min, indicating the accumulation of phenolic substances. At the same time, ROS were accumulated when plant tissue damaged by cutting, the activities of related antioxidant enzymes (SOD, APX and CAT) changed dynamically after oxidative damage. SOD and APX content increased significantly and reached the maximum value at 10 min after cutting, and then showed a downward trend. However, CAT activity increased sharply and reached the maximum value within 3 min after cutting, then maintained the same activity, and showed a downward trend after 30 min. These data fully demonstrated that the activities of browning related enzymes and gene expression increased with the prolonging of fresh cutting time. We explained the browning mechanism of fresh-cut eggplant by combining metabolomics and physiology, which may lay the foundation for better understanding the mechanism of browning during the fruits and vegetables during processing.

scholarly journals The Influence of Temperature, Storage Conditions, pH, and Ionic Strength on the Antioxidant Activity and Color Parameters of Rowan Berry Extracts

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3786
Author(s):  
Elena Cristea ◽  
Aliona Ghendov-Mosanu ◽  
Antoanela Patras ◽  
Carmen Socaciu ◽  
Adela Pintea ◽  
...  
Keyword(s):  
Antioxidant Activity ◽  
Ionic Strength ◽  
Organic Acids ◽  
Bioactive Compounds ◽  
Acid Methyl Ester ◽  
Storage Conditions ◽  
Raw Material ◽  
Thermal Treatments ◽  
Spectrophotometric Methods ◽  
Berry Extracts

Recent trends in the food industry combined with novel methods in agriculture could transform rowan into a valuable raw material with potential technological applications. Thus, the aim of this research was to investigate the content of bioactive compounds in its fruits and to assess the color and antioxidant stability of the extracts prepared from such fruits during various thermal treatments and at different pH and ionic strength values. Various spectrophotometric methods, HPLC, and capillary electrophoresis were used to quantify the concentrations of bioactive compounds—polyphenols, carotenoids, organic acids, and to assess antioxidant activity and color. The results show that rowan berries contain circa 1.34–1.47 g/100 g of polyphenols among which include catechin, epicatechin, ferulic acid methyl ester, procyanidin B1, etc.; ca 21.65 mg/100 g of carotenoids including zeaxanthin, β-cryptoxanthin, all-trans-β-carotene, and various organic acids such as malic, citric, and succinic, which result in a high antioxidant activity of 5.8 mmol TE/100 g. Results also showed that antioxidant activity exhibited high stability when the extract was subjected to various thermal treatments, pHs, and ionic strengths, while color was mainly impacted negatively when a temperature of 100 °C was employed. This data confirms the technological potential of this traditional, yet often overlooked species.

Modeling the Effects of Temperature, Sodium Chloride, and Green Tea and Their Interactions on the Thermal Inactivation of Listeria monocytogenes in Turkey†

2014 ◽  
Vol 77 (10) ◽  
pp. 1696-1702 ◽  
Author(s):  
VIJAY K. JUNEJA ◽  
JIMENA GARCIA-DÁVILA ◽  
JULIO CESAR LOPEZ-ROMERO ◽  
ETNA AIDA PENA-RAMOS ◽  
JUAN PEDRO CAMOU ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Sodium Chloride ◽  
Protective Effect ◽  
Heat Resistance ◽  
Green Tea ◽  
Thermal Inactivation ◽  
Heating Temperature ◽  
Lethal Effect ◽  
Interactive Effects ◽  
D Values

The interactive effects of heating temperature (55 to 65°C), sodium chloride (NaCl; 0 to 2%), and green tea 60% polyphenol extract (GTPE; 0 to 3%) on the heat resistance of a five-strain mixture of Listeria monocytogenes in ground turkey were determined. Thermal death times were quantified in bags that were submerged in a circulating water bath set at 55, 57, 60, 63, and 65°C. The recovery medium was tryptic soy agar supplemented with 0.6% yeast extract and 1% sodium pyruvate. D-values were analyzed by second-order response surface regression for temperature, NaCl, and GTPE. The data indicated that all three factors interacted to affect the inactivation of the pathogen. The D-values for turkey with no NaCl or GTPE at 55, 57, 60, 63, and 65°C were 36.3, 20.8, 13.2, 4.1, and 2.9 min, respectively. Although NaCl exhibited a concentration-dependent protective effect against heat lethality on L. monocytogenes in turkey, addition of GTPE rendered the pathogen more sensitive to the lethal effect of heat. GTPE levels up to 1.5% interacted with NaCl and reduced the protective effect of NaCl on heat resistance of the pathogen. Food processors can use the predictive model to design an appropriate heat treatment that would inactivate L. monocytogenes in cooked turkey products without adversely affecting the quality of the product.

Binding of 3-phosphoglycerate leads to both activation and stabilisation of ADP-glucose pyrophosphorylase from apple leaves

2005 ◽  
Vol 32 (9) ◽  
pp. 839
Author(s):  
Rui Zhou ◽  
Lailiang Cheng
Keyword(s):  
Heat Treatment ◽  
Thermal Stability ◽  
Enzyme Activity ◽  
Inorganic Phosphate ◽  
Thermal Inactivation ◽  
Specific Activity ◽  
Apple Leaves ◽  
Apparent Homogeneity ◽  
Adp Glucose Pyrophosphorylase ◽  
High Concentrations

Apple leaf ADP-glucose pyrophosphorylase was purified 1436-fold to apparent homogeneity with a specific activity of 58.9 units mg–1. The enzyme was activated by 3-phosphoglycerate (PGA) and inhibited by inorganic phosphate (Pi) in the ADPG synthesis direction. In the pyrophosphorolytic direction, however, high concentrations of PGA (> 2.5 mm) inhibited the enzyme activity. The enzyme was resistant to thermal inactivation with a T0.5 (temperature at which 50% of the enzyme activity is lost after 5 min incubation) of 52°C. Incubation with 2 mm PGA or 2 mm Pi increased T0.5 to 68°C. Incubation with 2 mm dithiothreitol (DTT) decreased T0.5 to 42°C, whereas inclusion of 2 mm PGA in the DTT incubation maintained T0.5 at 52°C. DTT-induced decrease in thermal stability was accompanied by monomerisation of the small subunits. Presence of PGA in the DTT incubation did not alter the monomerisation of the small subunits of the enzyme induced by DTT. These findings indicate that binding of PGA renders apple leaf AGPase with a conformation that is not only more efficient in catalysis but also more stable to heat treatment. The physiological significance of the protective effect of PGA on thermal inactivation of AGPase is discussed.

scholarly journals High temperatures during microsporogenesis fatally shorten pollen lifespan

2021 ◽  
Author(s):  
Maurizio Iovane ◽  
Giovanna Aronne
Keyword(s):  
Experimental Data ◽  
Heat Treatment ◽  
Heat Stress ◽  
High Temperature ◽  
Male Gametophyte ◽  
Crop Productivity ◽  
Anther Dehiscence ◽  
Optimal Temperature ◽  
Drastic Reduction ◽  
Crop Species

AbstractMany crop species are cultivated to produce seeds and/or fruits and therefore need reproductive success to occur. Previous studies proved that high temperature on mature pollen at anther dehiscence reduce viability and germinability therefore decreasing crop productivity. We hypothesized that high temperature might affect pollen functionality even if the heat treatment is exerted only during the microsporogenesis. Experimental data on Solanum lycopersicum ‘Micro-Tom’ confirmed our hypothesis. Microsporogenesis successfully occurred at both high (30 °C) and optimal (22 °C) temperature. After the anthesis, viability and germinability of the pollen developed at optimal temperature gradually decreased and the reduction was slightly higher when pollen was incubated at 30 °C. Conversely, temperature effect was eagerly enhanced in pollen developed at high temperature. In this case, a drastic reduction of viability and a drop-off to zero of germinability occurred not only when pollen was incubated at 30 °C but also at 22 °C. Further ontogenetic analyses disclosed that high temperature significantly speeded-up the microsporogenesis and the early microgametogenesis (from vacuolated stage to bi-cellular pollen); therefore, gametophytes result already senescent at flower anthesis. Our work contributes to unravel the effects of heat stress on pollen revealing that high temperature conditions during microsporogenesis prime a fatal shortening of the male gametophyte lifespan.

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