Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 15

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
Dekstrynę modyfikowano chemicznie przez estryfikacje mieszaniną diwodorofosforanu sodu i wodorofosforanu sodu, wysycanie jonami żelaza (III) oraz poprzez ogrzewanie z glicyną w 160°C. Uzyskane preparaty modyfikowano fizycznie poprzez działanie pola mikrofalowego w kuchenkach mikrofalowych o mocy 300 W i 750 W, lub prażenie w suszarce laboratoryjnej w temperaturze 160°C. Określano takie cechy sporządzonych modyfikatów dekstryny białej jak: rozpuszczalność sporządzonych preparatów (w temperaturze 30°C), lepkość 20% kleików oraz podatność na działanie enzymów amylolitycznych. Produkty estryfikowania dekstryny białej oraz ogrzewania jej z glicyną odznaczały się obniżoną rozpuszczalnością i lepkością tworzonych roztworów oraz mniejszą podatnością na działanie α-amylazy i glukoamylazy. Wysycanie dekstryny jonami żelaza (III) nie wpływało na jej właściwości. Poddawanie działaniu pola mikrofalowego oraz prażeniu dekstryn nie modyfikowanych chemicznie i dekstryn wysycanych jonami żelaza (III) powodowało podwyższenie ich rozpuszczalności, zmniejszenie lepkości ich roztworów oraz obniżenie podatności na działanie α-amylazy i glukoamylazy. Prażenie dekstryny estryfikowanej i poddanie działaniu pola mikrofalowego o mocy 750 W wywoływało podwyższenie rozpuszczalności oraz obniżenie podatności na działanie α-amylazy i glukoamylazy otrzymanego produktu. Poddawanie dekstryny modyfikowanej glicyną prażeniu i działaniu mikrofal powodowało niewielkie zmniejszenie jej rozpuszczalności oraz lepkości sporządzonych z niej roztworów.
Badano aktywność kwasotwórczą oraz stan fizjologiczny szczepu Y. lipoly- tica Wratislavia 1.31 podczas półciągłej biosyntezy kwasu cytrynowego z glicerolu odpa­dowego. Proces rozpoczęto jako hodowlę fed-batch, a następnie przeprowadzono 8 cykli hodowlanych, różniących się objętością wymienianego podłoża. W pierwszych czterech cyklach wymieniano około 30% (0,4 dm3), w kolejnych 40% (0,5 dm3) objętości robo­czej bioreaktora. Wymiana 0,4 dm3 podłoża umożliwiała otrzymanie do 175 g-dm-3 kwasu cytrynowego z wydajnością 0,66 g-g-1. Zwiększenie wymienianej objętości podłoża wpłynęło na obniżenie stężenia kwasu cytrynowego do 120 g-dm"3; wzrost stężenia bio­masy, erytrytolu oraz wzrost udziału w populacji komórek o objętości powyżej 60 m3. Ocena stanu fizjologicznego drożdży podczas długoterminowego procesu wykazała ich dobrą żywotność oraz wysoką stabilność genetyczną i fenotypową.
4
100%
The objective of this study was to determine the effect of heating a water dispersion of corn starch to various temperatures, followed by its freezing and defrosting, on selected properties of re-formed starch pastes. A suspension of starch was heated to various temperatures ranging from 59 to 94°C, and afterwards frozen and defrosted. The differential scanning calorimetry (Mettler Toledo, 822E) thermal characteristics of starch pre-heated to temperatures not inducing complete pasting revealed transitions of: (I) retrograded amylopectin, (II) non-pasted starch, (III) amylose-lipid complexes, (IV) retrograded amylose, and (V) highly thermostable starch structures. The application of higher temperatures during heating caused disappearance of transitions II and V. The increase of pre-heating temperature induced firstly a decrease and then stabilization of the swelling power as well as a successive decrease in starch solubility. Pastes pre-heated to temperatures over 79°C contained large macroparticles that were increasing viscosity of the re-formed starch paste (their size was positively correlated with viscosity value).
5
100%
This study was aimed at determining the effect of acetylation degree and crosslinking of retrograded starch with adipic acid on selected rheological properties of prepared pastes and gels. The esterification of retrograded starch allowed obtaining preparations with various degrees of substitution with residues of acetic (0.7–11.2 g/100 g) and adipic acids (0.1–0.3 g/100 g). Acetylation and crosslinking caused a decrease in amylose content of the preparations (3–21 g/100 g). Solubility of the preparations in water, in a wide range of variability, was increasing along with an increasing degree of acetylation and with a decreasing degree of crosslinking (19–100 g/100 g). Values of most of the rheological coeffi cients determined based on the flow curves of the prepared pastes and mechanical spectra of gels (3.5
The aim of the study was to obtain soluble and extruded starch preparations from potato starch, then to subject them to roasting with phosphates and/or glycin as well as to assess the effect of the order of double chemical modifications on their properties. The soluble starch was prepared by Lintner method, whereas the extruded starch was obtained using a single-screw extruder at 140-160-180°C. The starch preparations were produced using single chemical modification (roasting at 160°C with phosphates or glycin) as well as double modification of starch with a various order of the processes applied. The content of phosphorus, water solubility at a temperature of 30 and 80°C, resistance to amyloglucosidase activity and flow curves of the gelatinised starches were determined. The modifications carried out caused considerable changes in starch properties, and direction and extent of those changes were found to depend on the type and order of modifications. The modifications allowed obtaining the preparations of soluble starch with the resistance to amyloglucosidase activity accounting for nearly 20%.
The influence of resistant starch RS 4 on fatty acids composition in blood serum and liver of laboratory rats was investigated. 4 week experiment involved 32 males and 40 females of laboratory Wistar rats allotted in 4 groups in each sex. Control rats were fed ad libitum with standarized synthetic diet AIN-93. In experimental groups the animals were given modified feed enriched with 5% resistant starch. Monophosphate of potato starch (S1), monophosphate of potato starch soluble (S2) and monophosphate of potato starch heated with glycine and microwaved (S3), were examined. During the experiment period amount of consumed feed was monitored every two days and the rats were weighed once a week. Fatty acids composition in blood serum and liver was determined by gas chromatography method. Diet enrichment with resistant starch influenced fatty acids composition in blood serum of the animals. Obtained results show that the amount of total polyunsaturated fatty acids (PUFA) increased and simultaneously the amount of total monounsaturated fatty acids (MUFA) decreased in blood serum of the males. In blood serum of males and females fed the diets containing resistant starch (RS) favourable increase of arachidonic acid level was observed.
The retrogradation susceptibility of starch determines consumer suitability of food products rich in this polymer. Starch isolated from flour obtained from rye variety ‘Amilo’, which displays very low amylolytic activity, contains highest amounts of amylose and exhibits strong retrogradation susceptibility. Flour from rye ‘Dankowskie Złote’ and commercial rye flour type 720, that have higher amylolytic activity in comparison to ‘Amilo’, contain starch with lower amounts of amylose and reduced retrogradation susceptibility. Wheat starch displays lower degree of retrogradation in comparison to rye, because of larger amounts of phosphorus (phospholipids).
Starch is extensively used in the food industry as a texture modifier, a fat substitute, and in other applications. To optimise starch functional properties for specific use, it is subjected to various modifications. High-voltage electrical discharge (HVED) treatment, as a non-thermal and rapid process, was applied in this research as a single method and in combination with phosphorylation in order to explore its potential for improving starch physicochemical properties. Maize, wheat, potato, and tapioca starches were modified, and Na₅P₃O₁₀ and Na₂HPO₄ were used for phosphorylation. Starch gelatinisation parameters (by DSC); paste clarity; and contents of amylose, damaged starch, and resistant starch were determined; and FTIR-ATR spectra were recorded. All modifications reduced the enthalpy of gelatinisation and decreased contents of amylose, resistant starch, and damaged starch. The effect of the HVED treatment on starch properties depended on starch type and combinations with chemicals. HVED could act as an aid in the starch phosphorylation process since the properties analysed were more effectively improved when HVED was combined with phosphorylation than by phosphorylation alone.
Background. Resistant starch (RS) is part of potato starch that is not digested in the gastrointestinal tract. RS4 is a chemically modified starch (for example by oxidation and esterification) and physically (by heating). Objective. The study was aimed at determining the effect of resistant starch on lipid metabolism and activity of hepatic enzymes in Wistar strain rats fed high-fat diets containing 15% of lard or 15% of soybean oil. Material and methods. Four types of diets were administered to the animals (4 groups of males, n=32): control diet (K1) containing 15% of soybean oil; control diet (K2) containing 15% of lard as well as two groups receiving the same diets with 10% addition of resistant starch RS4 (K1S and K2S). Results. The mean concentration of total cholesterol was lower in the group of animals fed a diet with vegetable oil (39.9 mg/dl) as compared to that reported in the group of rats fed the lard-supplemented diet (55.2 mg/dl). Compared to the control groups in both groups of animals receiving the diet supplemented with resistant starch RS4 the total cholesterol concentration in serum decreased by ca. 25% (differences were statistically significant). In groups of rats receiving oil- or lard-containing diets with the addition of the resistant starch preparation the concentration of triglycerides in serum decreased by ca. 47% and 10%, respectively. Conclusions. A beneficial effect of the resistant starch RS4 added to Wistar rats diets on the lipid metabolism has been shown. The concentrations of total cholesterol and triglycerides in the serum were lower and concentration of HDL-cholesterol was higher in the rats fed with the diets containing the addition of the RS4 preparation as compared to the control groups. Based on the activity of hepatic enzymes the degree of liver damage was lower in groups of rats fed with diets containing resistant starch RS4 as compared to the control groups.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 1 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.