5-hydroxymethyl furfural formation and reaction kinetics of different pekmez samples: effect of temperature and storage

2012 ◽  
Vol 8 (4) ◽  
Author(s):  
Rasim Alper Oral ◽  
Mahmut Dogan ◽  
Kemal Sarioglu ◽  
Ömer Said Toker
Keyword(s):  
Reaction Kinetics ◽  
Arrhenius Equation ◽  
Storage Period ◽  
Effect Of Temperature ◽  
Temperature Changes ◽  
Juniperus Communis ◽  
Hydroxymethyl Furfural ◽  
Different Temperatures ◽  
And Storage ◽  
Kinetics Of

Abstract Pekmez (molasses) is a traditional food commonly produced from grape and other kind of fruit juices by evaporation processes. In this study, 5-Hydroxymethylfurfural (HMF) level of various pekmez samples was investigated during storage at different temperatures. HMF content of apricot, mulberry, carob, grape, Juniperus communis pekmez changed from 133.0 ppm to 1060.5 ppm, from 88.2 to 1921.5 ppm, from 11.1 to 1153.6 ppm, from 75.5 to 2077.0 ppm, from 19.9 to 280.1 ppm throughout eight months storage period, respectively. Samples of pekmez from the Juniperus communis had the minimum k values for each temperature that means HMF formation in these samples were slower than other pekmez types. The kinetic data analysis for HMF formation during storage was performed and an Arrhenius equation was used to determine the effect of temperature on reaction kinetics of 5-HMF formation in pekmez samples. Ea values were found between 10.58–37.73 (kcal/mol). Apricot pekmez was found as the least sensitive sample to HMF formation resulted from temperature changes.

scholarly journals Effect of Temperature during Drying and Storage of Dried Figs on Growth, Gene Expression and Aflatoxin Production

Toxins ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 134
Author(s):  
Ana Isabel Galván ◽  
Alicia Rodríguez ◽  
Alberto Martín ◽  
Manuel Joaquín Serradilla ◽  
Ana Martínez-Dorado ◽  
...  
Keyword(s):  
Gene Expression ◽  
Aflatoxin Production ◽  
Effect Of Temperature ◽  
Mycotoxin Production ◽  
Industrial Processing ◽  
Factors Associated ◽  
Different Temperatures ◽  
Major Producer ◽  
Main Factors ◽  
And Storage

Dried fig is susceptible to infection by Aspergillus flavus, the major producer of the carcinogenic mycotoxins. This fruit may be contaminated by the fungus throughout the entire chain production, especially during natural sun-drying, post-harvest, industrial processing, storage, and fruit retailing. Correct management of such critical stages is necessary to prevent mould growth and mycotoxin accumulation, with temperature being one of the main factors associated with these problems. The effect of different temperatures (5, 16, 25, 30, and 37 °C) related to dried-fig processing on growth, one of the regulatory genes of aflatoxin pathway (aflR) and mycotoxin production by A. flavus, was assessed. Firstly, growth and aflatoxin production of 11 A. flavus strains were checked before selecting two strains (M30 and M144) for in-depth studies. Findings showed that there were enormous differences in aflatoxin amounts and related-gene expression between the two selected strains. Based on the results, mild temperatures, and changes in temperature during drying and storage of dried figs should be avoided. Drying should be conducted at temperatures >30 °C and close to 37 °C, while industry processing, storage, and retailing of dried figs are advisable to perform at refrigeration temperatures (<10 °C) to avoid mycotoxin production.

A STUDY OF THE MECHANISM AND KINETICS OF THE SULPHITE PROCESS

1939 ◽  
Vol 17b (4) ◽  
pp. 121-132 ◽  
Author(s):  
J. M. Calhoun ◽  
F. H. Yorston ◽  
O. Maass
Keyword(s):  
Temperature Coefficient ◽  
Arrhenius Equation ◽  
Practical Interest ◽  
Effect Of Temperature ◽  
Wood Meal ◽  
Spruce Wood ◽  
Mechanism And Kinetics ◽  
Kinetics Of

The rate of delignification of resin extracted spruce wood-meal has been determined in calcium-base sulphite liquor at temperatures from 130 °C. down to 50 °C. No break was found in the temperature coefficient curve at the lower temperatures, the reaction following the Arrhenius equation closely. Possible mechanisms of the reaction are discussed in the light of existing theories, and the effect of temperature on the yield of pulp is pointed out for its practical interest.

scholarly journals Reaction Kinetics of Iron Oxides in Ok Tedi Magnetite Skarn Ore

2020 ◽  
pp. 1-13
Author(s):  
Mary Kama ◽  
Kaul Gena ◽  
Tindi Seje Nuru
Keyword(s):  
Reaction Kinetics ◽  
Papua New Guinea ◽  
Iron Reduction ◽  
New Guinea ◽  
Reaction Rate Constant ◽  
Close Monitoring ◽  
Significant Difference ◽  
Different Temperatures ◽  
C 30 ◽  
Kinetics Of

Magnetic skarn ore (MSO) is one of the major copper bearing ore extracted by the Ok Tedi Copper Mine in Papua New Guinea (PNG). Copper minerals are recovered by flotation while the iron not associated with copper are discarded as tailings. The objective of this investigation was to determine the iron ore reduction kinetics for the Ok Tedi MSO and ascertain if it can be processed to produce sponge iron for a mini steel plant in Papua New Guinea. SEM-EDAX analyses of the Ok Tedi MSO indicated 10.1% C, 30% O, 0.6% Mg, 1.1% Si, 21.1% S, 0.8% Ca and 36.2 % Fe. Most of the iron is in sulfide form. Both naturally occurring and roasted sinters of Ok Tedi MSO samples of different particle sizes were reduced by charcoal carbon at three different temperatures and seven different reduction times. Analyses of the reduced products indicated a metallic iron content of more than 65 wt. % on average. Results showed that there was no significant difference in reduction between fluxed and control materials. Only a slight increase in kinetics with reduced particle size, hence the reaction rate constant (K) did not vary much within the temperatures investigated. Reaction kinetics increases with increasing reduction time at 900°C. Therefore, more iron reduction is observed with particles of 106 µm size. In addition, the results also confirmed that the reduction energy used was higher at 800°C and lower at 1000°C. In conclusion, iron reduction can be improved but close monitoring of temperature and reduction times are essential to determine the reaction kinetics of the Ok Tedi MSO.

scholarly journals Degradation Kinetics of Anthocyanins in Shalgam Beverage

2019 ◽  
Vol 7 (2) ◽  
pp. 282
Author(s):  
Adnan Bozdoğan ◽  
Kurban Yaşar
Keyword(s):  
Activation Energy ◽  
Reaction Kinetics ◽  
Half Life ◽  
Degradation Kinetics ◽  
Production Method ◽  
Order Reaction ◽  
Different Temperatures ◽  
Traditional Production ◽  
Effects Of Temperature ◽  
Kinetics Of

This research was performed to elucidate the effects of temperature on the degradation kinetics of anthocyanins in shalgam beverage. Shalgam beverage was produced according to traditional production method. Then, it was kept at three different temperatures (65°C, 75°C, and 85°C) for 12 hours, and the relevant quantities of anthocyanins were determined thereafter. The research revealed that degradation of the anthocyanins was well described with a 1st-order reaction kinetics model and the R2 values varied in the range of 0.9059-0.9715. Activation energy of the reaction was determined to be 48537 Joule/mole. The half-lives of anthocyanins at 65°C and 75° C, and 85°C were found to be 138.63, 136.72, and 51.57, respectively. Compared the half-life periods at different temperatures, anthocyanins were found to be more resistant at 65°C and 75°C than at 85°C.

Modeling the effect of temperature on survival rate of Listeria monocytogenes in yogurt

2016 ◽  
Vol 19 (2) ◽  
pp. 317-324 ◽  
Author(s):  
J. Szczawiński ◽  
M.E. Szczawińska ◽  
A. Łobacz ◽  
A. Jackowska-Tracz
Keyword(s):  
Listeria Monocytogenes ◽  
Survival Rate ◽  
Storage Time ◽  
Ph Value ◽  
Effect Of Temperature ◽  
Natural Logarithm ◽  
Primary Model ◽  
Different Temperatures ◽  
Mathematical Equations ◽  
And Storage

Abstract The aim of the study was to (i) evaluate the behavior of Listeria monocytogenes in a commercially produced yogurt, (ii) determine the survival/inactivation rates of L. monocytogenes during cold storage of yogurt and (iii) to generate primary and secondary mathematical models to predict the behavior of these bacteria during storage at different temperatures. The samples of yogurt were inoculated with the mixture of three L. monocytogenes strains and stored at 3, 6, 9, 12 and 15°C for 16 days. The number of listeriae was determined after 0, 1, 2, 3, 5, 7, 9, 12, 14 and 16 days of storage. From each sample a series of decimal dilutions were prepared and plated onto ALOA agar (agar for Listeria according to Ottaviani and Agosti). It was found that applied temperature and storage time significantly influenced the survival rate of listeriae (p<0.01). The number of L. monocytogenes in all the samples decreased linearly with storage time. The slowest decrease in the number of the bacteria was found in the samples stored at 6°C (D-10 value = 243.9 h), whereas the highest reduction in the number of the bacteria was observed in the samples stored at 15°C (D-10 value = 87.0 h). The number of L. monocytogenes was correlated with the pH value of the samples (p<0.01). The natural logarithm of the mean survival/inactivation rates of L. monocytogenes calculated from the primary model was fitted to two secondary models, namely linear and polynomial. Mathematical equations obtained from both secondary models can be applied as a tool for the prediction of the survival/inactivation rate of L. monocytogenes in yogurt stored under temperature range from 3 to 15°C, however, the polynomial model gave a better fit to the experimental data.

THE REACTION BETWEEN CYANATE AND HYPOCHLORITE

1956 ◽  
Vol 34 (4) ◽  
pp. 489-501 ◽  
Author(s):  
M. W. Lister
Keyword(s):  
Activation Energy ◽  
Ionic Strength ◽  
Rate Constant ◽  
Hypochlorous Acid ◽  
Effect Of Temperature ◽  
Slow Step ◽  
True Activation Energy ◽  
Rate Of Reaction ◽  
Different Temperatures ◽  
Kinetics Of

The reaction between sodium hypochlorite and potassium cyanate in the presence of sodium hydroxide has been examined. The main products are chloride, and carbonate ions and nitrogen; but, especially if much hypochlorite is present, some nitrate is formed as well. The rate of reaction is proportional to the cyanate and hypochlorite concentrations, but inversely proportional to the hydroxide concentration: the rate constant is 5.45 × 10−4 min.−1 at 65 °C, at an ionic strength of 2.2. The rate constant increases somewhat as the ionic strength rises from 1.7 to 3.5. The effect of temperature makes the apparent activation energy 25 kcal./gm-molecule. The kinetics of the reaction suggest that the slow step is really a reaction of hypochlorous acid and cyanate ions, and possible intermediate products of this reaction are suggested. Allowing for the different extent of hydrolysis of hypochlorite at different temperatures, the true activation energy is found to be 15 kcal./gm-mol., which is consistent with the observed rate of reaction.

scholarly journals Effect of Packaging and Storage on Quality Characteristics of Dried Wild Pomegranate Arils (Anardana) Prepared in Solar Tunnel Drier

2020 ◽  
pp. 8-23
Author(s):  
Abhimanyu Thakur ◽  
N. S. Thakur ◽  
Hamid . ◽  
Pradeep Kumar ◽  
Kanchan Bhatt
Keyword(s):  
Value Added ◽  
Storage Period ◽  
Titratable Acidity ◽  
Punica Granatum ◽  
Storage Condition ◽  
Storage Conditions ◽  
Quality Characteristics ◽  
Ambient Conditions ◽  
Hydroxymethyl Furfural ◽  
And Storage

Wild pomegranate (Punica granatum L.) fruits were procured from Karsog area of Mandi district of Himachal Pradesh, India (1265 m above mean sea level). The arils extracted from the fruits were dehydrated in a solar tunnel (30-45°C) drier to prepare value added product Anardana. The developed product was packed in three different packaging materials viz. gunny bags, aluminium laminated pouches (ALP) and aluminium laminated pouches with vacuum (ALPV) and stored under ambient and refrigerated temperature for a period of 12 months so as to evaluate overall effect of storage period, storage condition and packaging material. After 12 months of storage period, higher retention of various quality characteristics like TSS, titratable acidity, ascorbic acid, total sugars, anthocyanins content, sensory characteristic scores with less increase in moisture content, NEB (non-enzymatic browning),HMF (hydroxymethyl furfural) and furfural content was observed in Anardana packed in ALPV followed by ALP and gunny bags. The changes in the quality characteristics of the Anardana were slower in refrigerated storage conditions as compared to ambient conditions.

scholarly journals emperature and storage periods on the maintenance of chemical composition of medicinal plants

2019 ◽  
Vol 5 (1) ◽  
pp. 40
Author(s):  
Priscila Leão ◽  
Leandro Neves ◽  
Ronan Colombo ◽  
Muhammad Shahab ◽  
Jane Oliveira ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Medicinal Plants ◽  
Eucalyptus Grandis ◽  
Storage Period ◽  
Chlorophyll Contents ◽  
Lippia Alba ◽  
Randomized Design ◽  
Different Temperatures ◽  
Total Anthocyanins ◽  
And Storage

Determining the chemical composition of medicinal plants used for therapeutic purposes is of fundamental importance. These plants must meet quality standards for commercialization by ensuring pharmacological properties and efficacy. However, for the maintenance of their active compounds, it is very important to store them at a suitable temperature and ensure the safety of these compounds. The objective of this work was to evaluate the effect of different temperatures and storage periods in the maintenance of chemical composition of bushy lippia (Lippia alba), crajiru (Arrabidaea chica), eucalyptus (Eucalyptus grandis), lemon grass (Cymbopogon citratus), citronella (Cymbopogon nardus) and sage (Lippia microphylla) leaves. Leaves of these medicinal plants were stored for different periods (30, 60 and 90 days) at different temperatures (0, 17 and 24 °C). A complete randomized design was used with five replications, each one with 150g of leaves. For each combination of temperature and storage period, different variables were evaluated such as phenolic compounds, total anthocyanins, antioxidant activity (ORAC and DPPH), carotenoids and chlorophyll contents. Leaves stored at 0°C resulted in the most efficient preservation of chemical compounds at 30, 60 and 90 days. However, this temperature causes physiological damage to the leaves. Therefore, for commercial use, dried or crushed leaves in the form of powder is recommended. Storage at 17 °C keeps the chemical composition of the leaves at satisfactory levels, while at 24 °C there is a significant decrease over the periods of cold storage.

Sign in / Sign up

Export Citation Format

Share Document