INFLUENCE OF THERMAL PROCESSING ON THE AMINO ACID COMPOSITION OF WHITE WHEAT BREAD

2018 ◽  
Author(s):  
И.М. ПОЧИЦКАЯ ◽  
Ю.Ф. РОСЛЯКОВ ◽  
В.В. ЛИТВЯК ◽  
А.Н. ЮДЕНКО
Keyword(s):  
Heat Treatment ◽  
Amino Acids ◽  
Treatment Time ◽  
Heating Time ◽  
Effect Of Temperature ◽  
Wheat Bread ◽  
Time Interval ◽  
White Wheat ◽  
Tyrosine Content ◽  
Increasing Temperature

Исследовано влияние температуры и длительности нагревания на деградацию аминокислот в пищевых продуктах. Образцы белого пшеничного хлеба подвергали термической обработке при температурах 90, 120, 150 и 180°С с интервалом в 30 мин в течение 2 ч. Количество аминокислот определяли методом высокоэффективной жидкостной хроматографии с предколоночной дериватизацией с использованием о-фталевого альдегида. Установлено, что с повышением температуры и увеличением длительности нагревания наблюдается снижение содержания аминокислот. Определены особенности реагирования аминокислот на воздействие температуры. Установлено, что на снижение содержания аспарагиновой кислоты в большей степени влияет высокая температура, чем время термообработки. Заметное снижение содержания тирозина в образцах выявлено при термообработке в течение 30–60 мин при температуре 180°С. Для аргинина характерно линейное снижение содержания при температуре 120–180°С. Содержание гистидина медленнее снижается при незначительном повышении температуры, а при высоких температурах увеличение времени термообработки ускоряет реакцию. Количество лизина существенно снижается при повышении температуры, а время нагревания влияет незначительно, причем чем выше температура, тем меньше влияние продолжительности нагревания. Отмечено повышение содержания отдельных аминокислот, что, возможно, связано с процессом ресинтеза. The aim of the work – study the effect of temperature and heating time on the degradation of amino acids. In the studies, samples of white wheat bread were heat treated at temperatures of 90, 120, 150 and 180°C with a time interval of 30 min for 2 h. Determination of the number of amino acids was carried out using HPLC from pre-columnar derivatization using o-phthalic aldehyde. It is established that with temperature increase and increase in duration of heating decrease in content of amino acids is observed. Some peculiarities of the reaction of amino acids to the effect of temperature have been established. For example, the decrease in the content of aspartic acid is more affected by the high temperature than the time of heat treatment. A noticeable decrease in tyrosine content is observed during heat treatment for 30–60 min at a temperature of 180°C. For arginine it is characterized by a linear decrease of the content in the range of 120–180°C. Histidine slows down with a slight increase in temperature, and at high temperatures, an increase of the heat treatment time accelerates the reaction. The amount of lysine falls more strongly with increasing temperature, and the heating time affects slightly, and, the higher the temperature, the less time affects. An increase in the content of individual amino acids is also noted, which is probably connected with the process of resynthesis.

INFLUENCE OF HEAT TREATMENT ON AROMA AND COLOR CHARACTERISTICS OF WHEAT BREAD

2021 ◽  
Author(s):  
И.М. ПОЧИЦКАЯ ◽  
Ю.Ф. РОСЛЯКОВ ◽  
В.В. ЛИТВЯК ◽  
Н.В. КОМАРОВА ◽  
Е.И. КОВАЛЕНКО
Keyword(s):  
Heat Treatment ◽  
Color Change ◽  
Consumer Preferences ◽  
Heating Temperature ◽  
Wheat Bread ◽  
Time Interval ◽  
White Bread ◽  
Color Changes ◽  
Color Characteristics ◽  
Essential Contribution

В формировании потребительских предпочтений важная роль отводится внешнему виду и аромату пищевых продуктов. При выпечке хлебобулочных изделий в процессе меланоидинообразования происходит изменение цвета и появление характерного хлебного запаха. Целью работы явилось исследование ароматобразующих веществ и цветовых характеристик белого пшеничного хлеба, подверженного термической обработке. Объектами исследований служили образцы белого пшеничного хлеба, нагревание которых проводили в сушильном шкафу при температурах 90, 120, 150, 180 и 210°С с интервалом в 10 мин на протяжении 2 ч. Исследование летучих компонентов осуществляли методом газовой хроматографии с масс-селективным детектированием. Образцы фиксировали фотоаппаратом Canon EOS 750D. В результате исследований обнаружено более 120 летучих веществ, идентифицировано 76, из них 31 существенно влияет на аромат белого хлеба. В основном это карбонильные соединения и низшие жирные кислоты, а также спирты, сложные эфиры и некоторые серосодержащие соединения. Анализ изменения цветовых характеристик белого пшеничного хлеба показал, что с увеличением температуры нагревания наблюдается значительное потемнение образцов. Если при температуре 90°С происходит еще незначительное изменение цвета, даже после 2-часового воздействия, то при увеличении температуры до 180–210°С цвет образцов хлеба темнеет в первые 10 мин и в последующем меняется незначительно. Таким образом, результаты исследований показали, что температуру и длительность обжарки необходимо оптимизировать для создания наиболее востребованных потребительских свойств продукта. In the formation of consumer preferences FOR food an important role belongs to appearance and aroma. At baking as a result of the melanoid formation process the color changes and typical of bread aroma appears. The purpose of work was studying the aroma-forming substances and color characteristics of the white bread at heat treatment. The objects of the research were samples of white bread heated in a drying oven at temperatures of 90, 120, 150, 180 and 210°C with a time interval of 10 minutes for 2 hours. The volatiles were investigated by gas chromatography with mass-selective detection. The image was recorded on a Canon EOS 750D camera. As a result of the research more than 120 volatile substances were detected, it is identified 76 from which 31 make an essential contribution to aroma of white bread. Basically, these are carbonyl compounds and lower fatty acids, as well as alcohols, esters and some sulfur-containing compounds. An analysis of the change in the color characteristics of white bread showed that with an increase in the heating temperature a significant darkening of the samples is observed. At a temperature of 90°C there is still a slight color change even after a 2-hour exposure to temperature, then as the temperature increases to 180–210°C, the color of the bread samples becomes darker within the first 10 minutes and then changes insignificantly. Thus, the results of research have shown that the temperature and duration of roasting should be optimized to create the most popular consumer properties of the product.

Influence of Post-deposition Heating Time and the Presence of Water Vapor on Sputter-coated Calcium Phosphate Crystallinity

2003 ◽  
Vol 82 (10) ◽  
pp. 833-837 ◽  
Author(s):  
Y. Yang ◽  
K.-H. Kim ◽  
C.M. Agrawal ◽  
J.L. Ong
Keyword(s):  
Heat Treatment ◽  
Water Vapor ◽  
Calcium Phosphate ◽  
Treatment Time ◽  
Heating Time ◽  
Heat Treatments ◽  
Titanium Implants ◽  
X Ray Diffraction ◽  
Bone Response ◽  
Post Deposition

Extensive research suggested that calcium phosphate (CaP) coatings on titanium implants are essential for early bone response. However, the characterization of CaP crystallinity and the means to control coating crystallinity are not well-established. In this study, the effect of a 400°C heat treatment for 1, 2, or 4 hours, and in the presence or absence of water vapor, on CaP crystallinity was investigated. Scanning electron microscopy indicated dense as-sputtered coatings. Increase in coating crystallinity was observed to be consistent with the increasing number of PO4 peaks observed as a result of different heat treatments. In addition, x-ray diffraction analyses indicated amorphous as-sputtered coatings, whereas crystalline CaP coatings in the range of 0-85% were observed after different post-deposition heat treatments. It was concluded that the presence of water vapor and post-deposition heat treatment time significantly affect the crystallinity of CaP coatings, which may ultimately affect bone healing.

scholarly journals PENENTUAN KOEFISIEN TRANSFER MASSA EKSTRAKSI KALIUM DARI ABU BATANG PISANG

Konversi ◽  
2012 ◽  
Vol 1 (1) ◽  
pp. 39
Author(s):  
Primata Mardina ◽  
Ajang Gunawan ◽  
Muhammad Imam Nugraha
Keyword(s):  
Mass Transfer ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Extraction Process ◽  
Effect Of Temperature ◽  
Average Error ◽  
Time Interval ◽  
Dimensionless Equation ◽  
The One ◽  
Increasing Temperature

 Abstrak-Kalium sebagai mineral alam bisa didapatkan dari batang pisang dengan cara ekstraksi padat-cair pada abu batang pisang menggunakan pelarut methanol. Penelitian ini bertujuan untuk mengetahui pengaruh suhu pada proses ekstraksi kalium dari abu batang pisang koefisien transfer massa proses tersebut. Proses ekstraksi ini dilakukan secara batch pada labu leher tiga yang dilengkapi dengan motor pengaduk, pendingin balik, termometer dan media pemanas. Abu batang pisang sebanyak 25 gram dan metanol 250 mL dimasukkan ke dalam labu leher tiga sebagai sampel. Ekstraksi dimulai dengan memanaskan sampel sampai suhu yang diinginkan, yaitu 30oC, 45 oC dan 60 oC, kemudian motor pengaduk dijalankan pada kecepatan yang telah ditentukan. Sampel diambil dalam selang waktu tertentu 0, 15, 30, 60, 120 180 dan 240 menit. Dari proses ekstraksi kalium dapat diketahui koefisien transfer massa. Hasil penelitian menunjukkan bahwa koefisien transfer massa semakin besar dengan semakin tinggi suhu operasi. Nilai koefisien transfer massa terbesar adalah 0,0235/menit pada suhu 60oC. Hubungan antara koefisien transfer massa dengan variabel-variabel yang mempengaruhinya dapat dinyatakan dengan persamaan dalam bentuk kelompok tak berdimensi sebagai berikut: Dengan ralat rata-rata 6,56 % Keywords: Ekstraksi, kalium, abu batang pisang,  Abstract-Potassium is the one of chemical compounds which can be extracted from ash of pseudo stem of banana by methanol solid-liquid extraction method. The experiment investigated the effect of temperature on mass transfer coefficient of potassium extraction process from ash of banana’s pseudo stem. This experiment conducted in a three necks flask which equipped with mechanical stirrer, condenser, thermometer and heating mantle. The sample was heated to desired temperature, 30oC, 45 oC and 60 oC. and maintained constant while reaction time. The reaction was timed as soon as the mechanical stirrer was turned on. Samples were drawn at specified time interval 0, 15, 30, 60, 120, 180 and 240 minutes. The result showed increasing temperature increased mass-transfer coefficient. The highest value of mass-transfer coefficient was 0,0235 /minute at 60oC.The correlation between mass transfer coefficient and investigated variables is shown in the dimensionless equation below: The average error is 6.56 % Keywords: Extraction, potassium, ash of banana’s pseudo stem.

scholarly journals Temperature dependence of amino acid hydrophobicities

2015 ◽  
Vol 112 (24) ◽  
pp. 7484-7488 ◽  
Author(s):  
Richard Wolfenden ◽  
Charles A. Lewis ◽  
Yang Yuan ◽  
Charles W. Carter
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Numerical Range ◽  
Thermal Environment ◽  
Equilibrium Constants ◽  
Effect Of Temperature ◽  
Side Chains ◽  
Surface Areas ◽  
Folded Proteins ◽  
Increasing Temperature

The hydrophobicities of the 20 common amino acids are reflected in their tendencies to appear in interior positions in globular proteins and in deeply buried positions of membrane proteins. To determine whether these relationships might also have been valid in the warm surroundings where life may have originated, we examined the effect of temperature on the hydrophobicities of the amino acids as measured by the equilibrium constants for transfer of their side-chains from neutral solution to cyclohexane (Kw>c). The hydrophobicities of most amino acids were found to increase with increasing temperature. Because that effect is more pronounced for the more polar amino acids, the numerical range of Kw>c values decreases with increasing temperature. There are also modest changes in the ordering of the more polar amino acids. However, those changes are such that they would have tended to minimize the otherwise disruptive effects of a changing thermal environment on the evolution of protein structure. Earlier, the genetic code was found to be organized in such a way that—with a single exception (threonine)—the side-chain dichotomy polar/nonpolar matches the nucleic acid base dichotomy purine/pyrimidine at the second position of each coding triplet at 25 °C. That dichotomy is preserved at 100 °C. The accessible surface areas of amino acid side-chains in folded proteins are moderately correlated with hydrophobicity, but when free energies of vapor-to-cyclohexane transfer (corresponding to size) are taken into consideration, a closer relationship becomes apparent.

Effect of Temperature on δ-Ferrite Morphology of Carbon Steel and Austenitic Stainless Steel Welds

2021 ◽  
Vol 1034 ◽  
pp. 23-32
Author(s):  
Le Thi Nhung ◽  
Nguyen Duong Nam ◽  
Pham Mai Khanh
Keyword(s):  
Heat Treatment ◽  
Sigma Phase ◽  
Treatment Temperature ◽  
Effect Of Temperature ◽  
Δ Ferrite ◽  
Steel Welds ◽  
Increasing Temperature ◽  
Hardness Values ◽  
Rate Research ◽  
Melted Metal

δ-ferrite was formed in the weld metal when the melted metal solidified to the room temperature. The δ-ferrite morphology depended on the composition, temperature gradient and growth rate. Research on the influence of heat treatment temperature (400°C, 600°C, 900°C) on the morphology changes and the δ-ferrite content is presented in this paper using optical microscopy, SEM, TEM. The δ-ferrite concentration reduced continuously in increasing temperature (from 23.5% after welding to 11% at 900°C for 10 hours). Besides, the formation of sigma phase and carbides at 600°C were the main cause of increasing hardness values in the fusion zone. However, the heat treatment at a temperature of 900°C eliminated both the sigma phase and brittleness.

scholarly journals Influence of Rapid Heat Treatment on the Shrinkage and Strength of High-Performance Concrete

Materials ◽  
2021 ◽  
Vol 14 (15) ◽  
pp. 4102
Author(s):  
Jan Stindt ◽  
Patrick Forman ◽  
Peter Mark
Keyword(s):  
Heat Treatment ◽  
High Performance ◽  
High Performance Concrete ◽  
Treatment Time ◽  
Precast Concrete ◽  
Concrete Strength ◽  
Shrinkage Strain ◽  
Temperature Treatment ◽  
Production Flow ◽  
Steel Fibres

Resource-efficient precast concrete elements can be produced using high-performance concrete (HPC). A heat treatment accelerates hardening and thus enables early stripping. To minimise damages to the concrete structure, treatment time and temperature are regulated. This leads to temperature treatment times of more than 24 h, what seems too long for quick serial production (flow production) of HPC. To overcome this shortcoming and to accelerate production speed, the heat treatment is started here immediately after concreting. This in turn influences the shrinkage behaviour and the concrete strength. Therefore, shrinkage is investigated on prisms made from HPC with and without steel fibres, as well as on short beams with reinforcement ratios of 1.8% and 3.1%. Furthermore, the flexural and compressive strengths of the prisms are measured directly after heating and later on after 28 d. The specimens are heat-treated between 1 and 24 h at 80 °C and a relative humidity of 60%. Specimens without heating serve for reference. The results show that the shrinkage strain is pronouncedly reduced with increasing temperature duration and rebar ratio. Moreover, the compressive and flexural strength decrease with decreasing temperature duration, whereby the loss of strength can be compensated by adding steel fibres.

scholarly journals Theoretical Effect of Temperature on Threshold in the Hodgkin-Huxley Nerve Model

1966 ◽  
Vol 49 (5) ◽  
pp. 989-1005 ◽  
Author(s):  
Richard Fitzhugh
Keyword(s):  
Relaxation Time ◽  
Relaxation Times ◽  
Giant Axon ◽  
Temperature Curve ◽  
Effect Of Temperature ◽  
Threshold Temperature ◽  
Ionic Conductances ◽  
And Shifts ◽  
The Right ◽  
Increasing Temperature

In the squid giant axon, Sjodin and Mullins (1958), using 1 msec duration pulses, found a decrease of threshold with increasing temperature, while Guttman (1962), using 100 msec pulses, found an increase. Both results are qualitatively predicted by the Hodgkin-Huxley model. The threshold vs. temperature curve varies so much with the assumptions made regarding the temperature-dependence of the membrane ionic conductances that quantitative comparison between theory and experiment is not yet possible. For very short pulses, increasing temperature has two effects. (1) At lower temperatures the decrease of relaxation time of Na activation (m) relative to the electrical (RC) relaxation time favors excitation and decreases threshold. (2) For higher temperatures, effect (1) saturates, but the decreasing relaxation times of Na inactivation (h) and K activation (n) factor accommodation and increased threshold. The result is a U-shaped threshold temperature curve. R. Guttman has obtained such U-shaped curves for 50 µsec pulses. Assuming higher ionic conductances decreases the electrical relaxation time and shifts the curve to the right along the temperature axis. Making the conductances increase with temperature flattens the curve. Using very long pulses favors effect (2) over (1) and makes threshold increase monotonically with temperature.

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