Browsing by Subject "kovuus"

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  • Toivola, Johanna Maria (Helsingfors universitet, 2015)
    The purpose of this study was to investigate the structure of ice cream, especially the effects of temperature, sugar composition and stabilizer-emulsifier concentration on the melt down, hardness and moulding properties of ice cream. The aim was to produce a soft and easily mouldable ice cream that suits the intended purpose. A sensory evaluation was conducted to the ice creams with desired structural properties. The literature review deals with ice cream ingredients, manufacturing process and factors affecting ice cream structure. For the experimental study, 16 ice creams with different compositions were made. The ice creams contained 12 or 6 % fat, different types of sugar compositions (A, B, C, D, E, F) and different concentrations of two types of stabilizer and emulsifier blends (A, B). Ice creams were stored at different temperatures. The hardness of ice cream was measured with a Texture Analyser, the melting rate was determined and the moulding properties were analysed with a moulding test. The two ice creams with desired structure were compared to a commercial ice cream in a sensory evaluation. The results of the hardness measurements revealed, that temperature and sugar composition affected hardness the most. Stabilizer and emulsifier concentration and type did not have an effect. The softest ice creams were those stored at higher temperatures and those made with sugar composition C, D, E and F. The slowest melting ice creams were the ones containing greater amounts of stabilizers and emulsifiers. The ice cream made with sugar composition D melted the fastest. For the moulding test, the softer ice creams were the easiest to mould. The ice cream made with sugar composition D was found to be too soft, almost runny, and the ones made with sugar composition A and B were found to be too hard. The ice creams made with sugar composition C, E and F were found pleasing. The batches containing a greater amount of stabilizer and emulsifier were found to be a bit gummy. In the sensory evaluation there were only one difference in sweetness found between the study ice creams and the commercial one. There were no differences found in creaminess and over all liking. From this can be concluded that the study ice creams are accepted by the consumers as well.
  • Rauta, Janne (Helsingin yliopisto, 2019)
    Extrusion is a versatile thermomechanical food processing technology, and cereal based snack products made with extrusion are one of the most significant ready-to-eat products. The literature review covered extrusion process in general while the effect of different components of grain and milk powders in extrusion was examined more closely, and also different methods to evaluate the properties and the quality of extrusion products were examined. The objective of the experimental study was to study the effects of sugar content and composition as well as the effects of different milk protein and water contents of the mass on the properties (water content, expansion and hardness) and organoleptic quality of extrudates. Experiments were carried out by using twin-screw extruder and the main component of extrudates was a mixture of oat flour and waxy maize starch. Three different milk powders were used (one lactose-containing and two lactose-free skimmed milk powders) in experiments, so that the milk protein content of mass was 8, 10 and 12 % (from solids) and water content 14, 16 and 18 %. The effect of sugar composition (lactose vs. glucose/galactose mixture) and sugar content (lowering the milk sugar content to about 60 % from solids) in extrusion was also examined. The water content, hardness and expansion of extrudates were measured. In sensory analysis (n=6) the effect of different milk powders and water contents on extrudates were evaluated. More expanded and less hard extrudates were obtained by adding milk powder that contained lactose compared to lactose-free milk powders. Lowering the sugar content did not affect the properties of extrudates significantly. Increasing the milk protein content of the mass increased the typical positive features of extrudates when lactose-containing milk powder was used, but when lactose-free milk powders were used the effect was the opposite. Increasing the water content of the mass decreased the expansion and increased the hardness of extrudates. In sensory analysis the major differences were observed in the darkness of color and the diameter of the extrudates. According to the results of the present study it is possible to obtain extrudates with good structure using lactose-containing milk powder as well as lactose-free milk powder. However, lactose-containing milk powder may be a better alternative in extrusion compared to the lactose-free milk powder. It may be possible, to some extent, to lower the sugar content of the extrudates that contain lactose-free milk powders without compromising the structural and organoleptical quality of the extrudates.
  • Tuukkanen, Eija (Helsingin yliopisto, 2018)
    An edible coating is defined as a thin layer of material, which can be eaten as part of the whole product. The literature review focused on edible coating materials, the preparation of the coat-ings and coating applications. The aim of the experimental work was to determine the suitability of different coating materials as an edible coating on the surface of the fresh cut carrots and parsnips and how roasting affected the coatings and coated root vegetables. The root vegetables were coated with three types of emulsions which were made from the soy protein isolate, chi-tosan and hydroxypropyl methylcellulose (HPMC K4M) using the dipping method. Further-more, the thyme essential oil was added to the coatings, mainly to provide aroma. The study also contained uncoated root vegetables. The samples were stored in a plastic bag or without a plastic bag. The shelf life of root vegetables was measured as the change in the weight caused by the loss of water vapor. The effect on the roasting was studied by baking loss, firmness and colour measurements. All tested coatings improved the appearance of root vegetables after the roasting and they did not impair the taste of root vegetables. The chitosan coating was the most suitable for the fresh cut and roasted root vegetables though further studies are needed to achieve optimal edible coatings for roasting. The coated carrots in a bag were redder than the uncoated carrots in a bag thus the colour was better preserved in the coated carrots. The coating itself was not enough to keep the root vegetables fresh during the storage. After roasting the root vegetables without the bag were considerably harder than the root vegetables in the bag. It is challenging to develop edible coatings suitable for the fresh cut and roasted vegetables. Coating has to stay on the surface of the vegetable and the properties of the coating must be designed for the vegetable in question. The moisture, respiration and purpose of use of the vege-table must be taken into consideration when developing such a coating.