Browsing by Subject "storage temperature"
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(2015)Beta-glucan ((1-3),(1-4)-?-D-glucan) is a soluble cell wall polysachharide in the starchy endosperm and aleurone layer of cereal grains. It is able to form the viscose solution at low concentrations and it can form gels under certain conditions. The literature review focused on physicochemical properties of beta-glucan. Especially gelling properties and influencing contributors for gelling were discussed. Aim of the experimental studies was to study effects of different solubilization temperatures on solution properties of barley beta-glucan. Furthermore, alteration on structuring properties of beta-glucan during the storage was observed. The study explored how beta-glucan behaves in water solution and does it has a gelling properties at low concentration. In this study pure barley beta-glucan (Megazyme, 99,5 %) (concentration 1 % v/w) was solubilized in water at three different temperatures (37, 60 ja 85 °C). Samples were stored at room temperature (+21 °C) and in the cold (+5 °C) for one week. Viscoelastic properties of the samples were measured by the dynamic rhelogical measurement with two different probes. Samples were treated with calcofluor-reagent and imaged by fluorescencemicroscopy. Furthemore, photographs were taken in three or four different dates during the storage time. Structure forming and gelling properties of pure barley beta-glucan differed among the samples when different solubilization temperatures were used. The pure barley beta-glucan was partly solubilized and formed opaque and smooth gel-like structure when 60 °C solubilizing temperature were used. Fluorescence microscopy showed that many unsolubilized particles were remained in both room and cold stored 60 °C samples. Unsolubilized particles formed rapidly continuous network structures during storage, especially in cold stored sample. Both 60 °C samples showed viscoelastic behavior and had weak gel properties which were observed by dynamic rheological measurement. Sample which was solubilized at 37 °C had part of structures gel-like after storage. Large unsolubilized particles were observed in 37 °C sample after solubilization which was also revealed by fluorescence microscopy. Sample which was solubilized at 85 °C was well-dissolved and formed clear solution. In 85 °C sample were few and small particles and gel-like structure did not formed during storage. However, formation of particle clusters was observed by fluorescence microscopy in all samples with particle sizes and structures increasing after storage one week. The results of this study indicated that solubilization and storage temperatures effected on forming particles and structures of pure barley beta-glucan during storage. This study showed that solubilization temperature effected on gelling properties of pure barley beta-glucan at low concetration.
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(2021)The breaking of albumen during the mechanical peeling process of cooked eggs causes food waste. The aim of this thesis was to study the effect of housing system, storage temperature and age of hens on the albumen quality and gelation. In addition, the objective was to compare the properties of eggs collected from different quality batches of industrially cooked eggs. Uncooked eggs were collected from different batches before cooking, and the air cell size, albumen pH and dry matter content were measured. Haugh unit score describing the quality of egg was also measured. The same measurements were also made to eggs produced with two different housing systems, to eggs stored at 4°C and 14°C and to eggs from three different age groups of layers once a week during the total storage time of four weeks. The egg size was measured, and shape index, volume and surface area of eggs were calculated. Egg shell thickness was measured, and pore count was determined with stereomicroscope after dyeing the shells with methylene blue. The protein composition was examined with SDS-PAGE. A microwell plate analysis was tested in order to determine the S-ovalbumin content in albumen. Pieces of coagulated egg white were analysed with texture profile analysis and fracture study. The age of the hen had an impact on egg quality. Coagulated egg white samples made of eggs from old hens fractured more easily than samples made of eggs from young hens in all timepoints. The Haugh unit scores were lower in eggs from old hens and dry matter contents increased faster in eggs from young hens compared to the other age groups. Differences between production methods were also noted, and albumen from organic eggs fractured easier than albumen from barn eggs. Haugh unit scores and dry matter contents were lower and pH-values greater in organic eggs compared to barn eggs. Lysotzyme contents based on SDS-PAGE were lower in organic eggs compared to barn eggs. Shells were thinner and pore counts greater in organic eggs compared to barn eggs. Storage temperature had an impact on uncooked egg quality, and eggs stored at 14 °C had lower Haugh unit score and greater pH and dry matter content than eggs stored at 4°C. Textural properties of eggs stored at 14°C were better only in the first two timepoints. Eggs collected from low quality batches of industrially cooked eggs were laid by old layers and had albumen pH more basic and dry matter content and Haugh unit score lower than eggs collected from batches with good quality. Measuring these properties could be helpful when choosing the eggs for the cooking process, because great dry matter content had an positive impact on textural properties of cooked albumen, but the decrease in Haugh unit score over time possible had an negative impact on textural properties.
Now showing items 1-2 of 2