Browsing by Subject "määritysmenetelmä"

At low concentrations, biogenic amines (BA) promote natural physiological activity, but at higher concentrations they can cause a wide variety of health hazards, especially for more sensitive individuals. The BA determination in wine is challenging due to the variation in physicochemical properties and the potential matrix effects of other compounds in the sample. It is important to develop efficient sample purification methods to minimize matrix interference. Derivatization is required for most biogenic amines due to the absence of chromophores. The conditions that promote the origin or formation of biogenic amines in wines are not yet fully understood, as many factors contribute to their formation. The main sources or stages of BA formation during wine-making should be identified in order to reduce BA levels by corrective measures. Currently, the analytical community is striving for more environmentally friendly methods. The literature review examines methods for determination of biogenic amines in wines from 2005 until 2020. The methods are high-performance liquid chromatography, ultra-high-performance liquid chromatography, high-temperature liquid chromatography, nano-liquid chromatography, micellar liquid chromatography, capillary electrophoresis, micromachined capillary electrophoresis, gas chromatography, immunoassay, sensor, colorimetric method, thin-layer chromatography and ion chromatography. The health disadvantages of biogenic amines and the problem areas associated with their determination from a complex wine matrix, such as matrix effect and derivatization, are also surveyed. In addition, changes in the BA profile during different stages of winemaking and storage, as well as the effect of the grape variety and lactic acid bacterial strain on the BA profile, are surveyed. Validation determines the suitability of a method for its intended use. In the methods for determining the literature review, measurement uncertainty - possibly the most important validation parameter - had not been determined in any of the validations. The aim of the research project was to obtain a functional and validated method for the determination of biogenic amines in wines for the Alcohol Control Laboratory at Alko Inc. In the method tested, histamine, tyramine, putrescine, cadaverine, phenylethylamine and isoamylamine derivatized with diethyl ethoxymethylene malonate were determined by high-performance liquid chromatography and diode array detector. The method was not sufficiently reliable, so a competitive enzyme-linked immunosorbent assay for the determination of histamine in wines was introduced, which provided a useful method for the Alcohol Control Laboratory. The validation determined specificity/selectivity, recovery, repeatability, systematic error, estimation of random error, measurement uncertainty, expanded measurement uncertainty, limit of detection and limit of quantification. The European Food Safety Authority has confirmed histamine and tyramine as the most toxic amines. The International Organization of Vine and Wine has not set legal limits for BA levels, but some European countries have had recommended maximum levels for histamine. Many wine importers in the European Union require a BA analysis even in the absence of regulations. Based on the literature review, high BA levels were found in the wines under study, including levels of histamine, tyramine, and phenylethylamine that exceeded the toxicity limits. Some wines had biogenic amines below the detection limit, so the production of low-amine wines is possible. In addition, certain strains of lactic acid bacteria were found to significantly reduce the BA levels in wine. High-performance liquid chromatography is the most widely used determination method. An increasing trend is to develop simpler methods such as the portable sensor-based method.

Vastasyntyneillä varsoilla ei ole lainkaan vasta-aineita veressään, minkä vuoksi ne tarvitsevat heti synnyttyään ternimaitoa, josta vasta-aineita imeytyy ruuansulatuskanavan kautta verenkiertoon. Mikäli vasta-aineiden saaminen epäonnistuu, varsat eivät pysty taistelemaan ympäristön patogeeneja vastaan ja ovat suuressa riskissä sairastua vakaviin yleistulehduksiin, jotka voivat johtaa sepsikseen ja kuolemaan. Epäonnistunutta vasta-aineiden saantia kutsutaan FPT:ksi (failure of passive transfer) eli vasta-ainepuutokseksi. FPT on tärkeä tunnistaa nopeasti ja luotettavasti heti sairaan varsan vierellä. Yliopistollisessa Hevossairaalassa FPT:n tunnistamiseen käytetään SNAP-foal IgG -pikamenetelmää, jolla mitataan varsan veren vasta-ainepitoisuutta semikvantitatiivisesti. Menetelmä ei kuitenkaan ole täysin luotettava, minkä vuoksi tutkimus vaihtoehtoisista menetelmistä oli tarpeen. Lisensiaatintyön tutkimusosuudessa verrattiin SNAP-testiä uuteen LUCIA foal IgG -menetelmään ja tulokset tarkistettiin SRID:llä (Single Radial Immunodiffusion), joka on vasta-ainepitoisuuden määrityksessä käytetty standardimenetelmä. Tutkimukseen käytettiin Hevossairaalan potilasvarsoista kerättyjä ylijäämäverinäytteitä. Kaikki menetelmät suoritettiin valmistajien ohjeiden mukaisesti. Lisäksi tutkittiin LUCIA-menetelmään vaikuttavia mahdollisia virhelähteitä, kuten näytteiden pitkää säilytysaikaa ja eri verituotteesta määritystä, sillä näitä ei ollut tutkittu aikaisemmin. Molemmille vertailtaville menetelmille laskettiin niiden luotettavuudesta kertovat herkkyys ja tarkkuus sekä ennustearvot. Odotuksena oli, että LUCIA täysin kvantitatiivisena menetelmänä on luotettavampi. Aiempien tutkimusten perusteella odotettiin, että SNAP-testin tarkkuus olisi heikko. Tutkimuksessa todettiin odotusten mukaisesti, että LUCIA on herkempi kuin SNAP-menetelmä ja sen negatiivinen ennustearvo on huomattavasti parempi. Vastoin odotuksia, molemmat testit olivat kuitenkin tarkkuudeltaan yhtä hyviä. Tutkimuksessa todettiin, että LUCIA:n tuloksiin ei vaikuttanut näytteiden pitkä jääkaappisäilytys eikä käytetty verituote. SNAP-testin käytössä oli suurempi todennäköisyys virheisiin ja sen tulokset olivat vaikeampia tulkita kuin numeerisen vastauksen antavan LUCIA-testin. LUCIA todettiin kaiken kaikkiaan luotettavammaksi menetelmäksi ja sen antama numeerinen tulos voi helpottaa hoitopäätösten tekoa

A range of different factors affect the composition of a sausage. The main objectives of this thesis were to research and define which factors have an impact on the firmness of the gel in sausages and to develop a method to define the composition of a warm sausage. Anchoring agents and fillers are added into sausages to improve the composition and flavour and to decrease the manufacturing costs. Most of the anchoring agents are proteins, however starch is also used. Starches are very viable anchoring agents. Gelatinised starches absorb or bind water and make it possible to have more water in a sausage. The research was composed of two phases in which the variables were the ingredients of the sausages. The factors that have an impact on the composition of sausages were analysed using statistical tests and variance analysis. In the first phase of the research a method to measure the firmness of a warm sausage was developed. The density of the gel was measured by sensory analysis and by Instron mechanical testing using the research method. The method was based on raising the core temperature of sausages above 49 °C to make the solid collagen soluble. Using a double boiler the core temperatures of the samples were adjusted to the desired level after which the samples were placed in the Instron mechanical tester in a styrox mold to limit the heat conduction. In addition to the mechanical tests a consumer survey to define the optimal eating temperature was included in the development of the research method. The results obtained by using the research method and the results from the sensory test had a correlation. In the future it is possible to skip sensory testing and use only this method to define the composition of a warm sausage. The method was used in the second phase of the research when studying the effects of different ingredients on the firmness of the gel in sausages. The results indicated that the composition of a sausage does undergo changes when heated.