Gabonaminősítő módszerek fejlesztését megalapozó kutatások

Egy búzaalapú termék fejlesztésénél, minőségének stabilizálása során szükséges tudnunk, hogy milyen tényezők befolyásolják az adott minőséget. A minőségközpontú búzanemesítés is igényli a minőség-összetétel közötti kapcsolatok tisztázását, a befolyásoló tényezők hatásának megismerését. A nemzetközi gyakorlatban hasonló célra is különböző módszereket alkalmaznak, másrészt sok esetben csak kis mennyiségű minta áll rendelkezésre. A kutatómunka eredményei: - 30 fajtaazonos búzából készült liszt minősítését végeztük el valamennyi, nemzetközileg elfogadott vizsgálati módszerrel, illetve eszközzel, úgymint: Valorigráf, Farinográf és Mixográfos, Alveográf, nyújthatóság, Zeleny-index, esésszám, gyors viszkoanalizátor (RVA). Egyes paraméterek között szoros összefüggést tártunk fel. - Egyes vizsgálatokat a részben a Tanszéken kifejlesztett mikro-módszerekkel is elvégeztük. A validálás eredményei a mikro-módszerek alkalmazhatóságát bizonyítják. - Egyes adott fehérje alegységek, és azok aránya (Glu/Gli arány), valamint a technológiai paraméterek között összefüggés állapítható meg. - Az idegen fehérjék (pl. amaránt, hüvelyes fehérjék) általában rontják a hagyományos sütőipari minőséget, ami jórészt a fehérjeszerkezet különbözőségéből adódik. - Az eredmények véleményünk szerint a gyakorlatban is jól használhatók. Pl. a módszerek számának csökkentése, paraméterbecslés az összefüggések alapján; fehérje-alegységek beépítése a nemesítése során, illetve a mikro-módszer alkalmazása a gyakorlatban. | At the product development or in the breeding process, the knowledge about the relationship between the quality and the chemical composition is necessary. However, different methods are used for the determination of wheat or flour quality, depending on the goal of the utilisation, the tradition, or the accepted standards. In some cases ?like breeding, or R+D experiments- only limited amount of samples are available. The main results of this research work are the following: - The quality of 30 different wheat species was studied with all, internationally accepted methods: Valorigraf, Farinograf és Mixograph, Alveográph, Extensograph Zeleny-test, falling number method, rapid visco-analyser (RVA) vas used in studies. Sicnificant relationships were detected is some cases between different parameters. - Micro-methods were also used in cases of valorigraph, farinograph, extenzograph and Zeleny-test. These methods and instruments were partly developed at the Department. The results of validation established and confirmed the adaptability of the new procedures. - In some cases, relationships were found between given protein subunits or the rates of glutenin and gliadin, and the different measured parameters. - Usually, the addition of non-wheat proteins to the wheat flours decreases the quality parameters. The possible reason is the very different protein structure. - In our opinion, these results are also utilisable in the every-day practice

STUDY OF THE RHEOLOGICAL PROPERTIES OF MYOSIN-PLANT PROTEIN SYSTEMS DURING THERMOTROPIC GELATION

Model systems containing myosin mixed with native and slightly preheated plant protein preparations (soy glycinin, sunflower seed protein isolate, wheat gluten, wheat gliadin and wheat glutenin) and experimental sausages from beef meat and added protein preparations were studied after heat treatment for textural properties using an Instron 1140 apparatus. All non-meat preparations caused decrease in cohesivity and elasticity except glutenin. Vital gluten and soy glicinin had some advantages in comparison to sunflower seed protein. Preheating of gluten for 30 and 45 minutes resulted in significant increase in hardness and chewiness but not in elasticity. Preheating of soy glycinin for 45 minutes caused significant changes in work of compression, elasticity and chewiness

INVESTIGATION OF THE FOAMING PROPERTIES OF SOME FOOD PROTEIN PREPARATIONS

The foaming properties of 10 different protein isolates and protein preparations (wheat germ-, barley germ-, maize germ protein, lentil-, pea-, soy protein, ovalbumin, bovine serum albumin = BSA, casein and lysozyme) were investigated using volumetric and conductometric methods. According to the volumetric method casein and BSA had the best foaming power. Good foaming power was observed with maize germ-, soy-, pea-, barley germ proteins and ovalbumin. The foam forming ability of wheat germ protein and lysozyme was the lowest. On the basis of conductometric results the proteins investigated may be divided in to the same three groups: However, within the group some changes in the order of proteins may occur. In calculating the linear correlation between the two methods an improvement of correlation (r = 0.93) was achieved by modifying the evaluation of conductometric curves. Maize germ-, soy and lentil protein showed the best foam stability and barley germ protein the lowest one according to conductometric results. The correlation between the foam stability data obtained by the two methods is very poor

CONCENTRATIONS OF CITRATE AND KETONE BODIES IN COW´S RAW MILK

The milk composition of high-yielding dairy cows is highly related to their nutrition. The energy deficiency in dairy cows can cause subclinical or clinical ketosis. In ketotic state the concentration of ketone bodies (acetone, AC; acetoacetic acid, ACAC; and β-hydroxybutyric acid, BOHB) increases in the different body fluids and simultaneously, changes in concentration of other compounds are also expected. The authors´ hypothesis is that the members of the TCA-cycle, such as citric acid (CA) also change in association of increased formation of ketone body. To support this hypothesis the concentrations of ketone body components and CA were parallel measured and their relationship was studied in raw milk samples. Based on the AC concentration of the milk samples two groups were formed retrospectively: High Acetone (HA) Group (n=41) of AC concentration >0.4mM and Low Acetone (LA) Group (n=78) with the AC level ≤ 0.4 mM. In all samples very low ACAC level was found, which is a consequence of the spontaneous decarboxylation of ACAC to AC during the usual sample storage. Focusing on the results of HA Group the authors found significant relationship between CA and ketone bodies and a parallel drop of AC and CA during the metabolically crucial first 1-4 weeks of lactation. For this reason they suggest to introduce simple, easy, automated methods to determine AC and/or CA concentration in raw milk

The behavior of hypersensitivitycausing proteins during food processing

Since the components causing hypersensitivity reactions (allergies, celiac disease) are usually proteins, therefore, learning about their potential changes is important from the food safety point of view. If the proteins undergo various structural modifications during processing, their determination in foods could be problematic. Nevertheless, the fact that these altered proteins cannot be detected using analytical methods does not necessarily mean that they cannot cause adverse reactions in the human body. Answering the questions that arise in connection with this topic requires the cooperation of patients, clinicians and analysts as well. Foods intended for final consumption undergo several processing steps while going from raw material to final product. Each process that alters the structure of proteins is also expected to have an effect on their binding to antibodies. Food processing procedures cause a number of physical, chemical and biochemical changes that can affect the allergenic properties of a protein. Depending on the properties of the protein, the type, length and intensity of the processing operation, or the matrix, the allergenic effect of a protein can be increased, decreased, or left unchanged by processing. ELISA tests, which are currently used in routine methods, employ various antibodies, so the epitopes targeted in the immune responses can also be different. The various epitopes can undergo different modifications during food processing, therefore, their affinity to the antibody can also change, which can affect the results provided by the method. This phenomenon calls attention to the fact that the accuracy of commercially available methods is questionable, and so both the improvement and harmonization of immunoanalytical methods is necessary

Az élelmiszerallergének mérésének lehetőségei ma - kihívások, megoldások, a fejlesztés irányai = Possibilities of allergen analysis at present - challenges, solutions and directions of development

Az élelmiszerekkel szemben jelentkező túlérzékenységi reakciók (allergia, intolerancia) a népesség egyre növekvő hányadát érintik. Ezen betegségek egyetlen hatékony kezelési módja az érzékenyítő komponensek étrendből történő teljes elhagyása. Az EU jelenleg 14 olyan allergén komponenst tart számon, melyek jelölése kötelező az élelmiszerek csomagolásán. A szabályozás betartásához megfelelő technológiára és ennek támogatására érvényesített (validált) analitikai módszerekre van szükség. Napjainkban az allergének mérésére az immunanalitikai módszerek (ELISA, LFD) a legelterjedtebbek. Ezen módszerek fejlesztése és validálása több nehézségbe ütközik. A reakciót kiváltó fehérjék összetétele nem minden esetben ismert, valamint nem állnak rendelkezésre sem referencia-anyagok, sem referenciamódszerek. Em ellett a feldolgozási folyamat hatásait is meg kell ismerni és figyelembe kell venni. A problémamegoldás egyik iránya allergén fehérjét deklarált mennyiségben tartalmazó feldolgozott élelmiszermátrix fejlesztése, mely kutatásaink egyik fő célja. Siker esetén a mintamátrix referencia-anyagként is használható, melynek segítségével lehetőség nyílik a feldolgozási folyamat hatásainak vizsgálatára, valamint a kereskedelmi forgalomban kapható ELISA tesztek összehasonlító elemzésére is. Hypersensitivity reactions (allergy and intolerance) triggered by certain food proteins affect an increasing rate of population. The only effective treatm ent of these illnesses is the total avoidance of the problem atic proteins from p atien t’s diet. At the m om ent the labelling regulations of E uropean Union defines 14 foodstuffs or com ponents which are responsible for the highest number of these cases. In order to comply the regulation, right technological solutions and validated analytical methods are needed. At present, the most commonly used methods in allergen analysis are immune-analytical based ELISA or LFD kits. The development and validation of these methods cause many challenges. The compositions of allergenic proteins are not welldefined, furthermore neither reference materials nor reference methods exist. Finally the effects of food processing steps on the allergenic proteins and the results of the analytical methods are not described well. One direction towards overtaking the problems is the developm ent of incurred real food matrices which contains dedicated amount of allergenic protein, which was the main goal of this work. These model matrices can be used as incurred reference material (IRM) and opened the door to investigate the influence of food processing. Reference material also give the opportunity to make a comparative study of ELISA kits and other analytical methods

Kis molekulatömegű polipeptidek hatása a polimer glutenin polimerizációs fok szerinti eloszlására és a sikérkomplex reológiai sajátságaira = The effect of low molecular weight polypeptides on the polymerization degree distribution of polymeric glutenin

A búza sikéralkotó fehérjéinek a bioszintézisét tanulmányoztuk a búzaszem fejlődése során a virágzástól számított 12. naptól kezdve a szemek teljes beéréséig. Öt magyarországi termestésű búzafajtát vontunk be a kísérletbe és három évjárat termésének a vizsgálatára került sor. A búza termesztése részben kísérleti gazdaságokban (Martonvásár, Monor) , részben üzemi buzatermelőknél (Mezőterm, Lórév). Fontosabb megállapításainkat a következőkben foglaljk össze. Bár az egy szemre számított teljes fehérjetartalom növekedését általában szigmoid jellegű görbe jellemzi, a termelési feltéelek hatására jelentő eltérések léphetnek fel. Az egyes fehérjék szintézisének sorrendje és a transzláció sebessége jelentősen változik. A metabolikusan aktív fehérjék szintézisét követően már a korai fejlődési szkszban megindul a sikéralkotó polpeptidek szintézise gliadinok, LMW, HMW peptidek sorrendben. A glutenin alegységek polimerizációja csak egy kritikus koncentráció elérés után indul meg. A sikér kialakulás megkezdődésének még további feltétele a glutenin meghatározott átlagos polimerizációs fokának az elérése. A sikéroldatok relatív viszkozitásának a követése alkalmasnak bizonyult a polimerizációs folyamat követésér. A vizsgálati adatok megerősíették a glutenin polimer linearis jellegét. | The biosynthesis of gluten forming polypeptides was studied starting from 12-th day after anthesis till full ripeness of wheat kernels. Five wheat cultivars, grown in Hungary were used in experiments and three years crops were studied. The wheat was grown partly in experimental stations (Martonvásár, Monor) and partly in commercial wheat producing farms (Mezőterm, Lórév). The most important statements of research are the following ones: Although the total protein content (calculated on single kernel) may be characterized by a sigmoid curve, the growing conditions may sinificantly change its form. The sequence and rate of translation of individual proteins is diffrent. After synthesis of metabolically active proteins, even in early phase of kernel development starts the synthesis of gluten forming peptides, in an order: gliadins, LMW- and HMW polypeptides. The polymerization of glutenin subunits starts only after the concntraton of subunits reches a critical concentration. The prerequisite of gluten formation is n addition a critical average polymerization level of polymeric glutenin. The follow of the relative viscosity of gluten solution was suitable for the control of growing average polymerization degree of glutenin. The experimetal data of viscosity measurements and their evaluation confirmed the linear character of molecules of polymeric glutenin

Development of separation techniques for complex characterization of plant proteins and carbohydrates

In the Research Group of Cereal Science and Food Quality at the Department of Applied Biotechnology and Food Science of BME, separation technique has been part of the methods used for the complex quality assessment of food and food ingredients for a long time. Our colleagues working in our current and predecessor department achieved serious results with the help of their separation technique methods, for example in the analysis of protein and carbohydrate composition, analysis of lipids (fatty acids), quantitative and qualitative evaluation of biogenic amines and amino acids, etc. In addition to determining the composition of the raw material, the impact of different molecules on quality and technological properties was always an important question. It was always possible to investigate this using the modern tools and methods of the time, so the application of gel chromatography, high-performance liquid chromatography, gas chromatography and electrophoretic techniques determined the quality of both research and education. In recent years, the research group has mainly dealt with the quality of grains, their composition, their technological potential and their evaluation from a food safety aspect. For the research of these areas, molecular level (mainly protein and fibre composition) examinations have become essential, for which modern electrophoretic and chromatographic methods are excellent tools. However, their proper application is a great challenge, because in most cases, serious method development and/or method adaptation and partial validation tasks are required for their routine use. In the following, we provide a brief overview of the projects and results achieved in our research group in the field of separation techniques through a few application examples