Browsing by Subject "ice cream"

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  • Heikkilä, Pirketta (Helsingfors universitet, 2011)
    The focus of the literature review of the study was on ice cream, different kinds of coatings used in the food industry and coating methods. In addition, the typical combosition of chocolate, rheological properties of liquid chocolate and the interaction between the consistency and rheological properties were reviewed. The objective of the study was to find out how consistency and coating temperature affects viscosity, yield value, solidification time and the amount of the coating layer in ice cream stick. The idea was primarily to find out how the amount of the coating layer could be controlled. Variables selected in this study were the amount of fat and emulsifiers in the milk chocolate coating and the coating temperature. The amount of coating layer, solidification time of the coating and viscosities and yield values of liquid coating were measured. The xperiment was planned using a Box-Behnken design. Results were calculated with regression analysis. Response surface methodology was used to estimate how the changes in fat amount, emulsifier amount and temperature affected the amount, solidification time, viscosity and yield value of coating. Increasing the amount of fat significantly decreased the amount, solidification time, viscosity and yield value of the coating. Increasing the amount of emulsifier decreased the amount, solidification time and yield value of the coating. Increasing temperature of the coating decreased the amount and viscosity of the coating, but increased solidification time of the coating. From the results, temperature, fat content and emulsifier content of the coating were found to affect the amount of the milk chocolate coating layer on an ice cream stick. Response surface methodology foud to be suitable method for investigating the amount of chocolate coating. Methods to control the amount of coating layer were examined by means of response surface methodology.
  • Toivola, Johanna Maria (Helsingin yliopisto, 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.
  • Neffling, Jonna (Helsingfors universitet, 2009)
    The literature review of this thesis deals with light, conventional light sources and the effects of light on the quality of foods. Impacts of light on the quality of frozen foods were also discussed. Effects of fluorescent light on frozen food have been previously reported in the literature, but effects of LED light have not. The literature review also deals with the quality changes of foods caused by freezing and frozen storage. The significance of package during frozen storage was reviewed. The aim of the experimental study was to investigate whether there are differences between the effects on frozen food when exposed to fluorescent or LED light. Frozen strawberries, shrimps, lamb loins and ice cream were exposed to fluorescent and LED light for 4 weeks. The samples were packed in transparent LDPE pouches except the lamb loins, which were vacuum-packed in transparent PA/PE film. References were packed in aluminium foil. Temperature of the samples was monitored by the sensors attached to the surfaces of the packages. The colour of the samples was measured every week using a spectrophotometer. Thiobarbituric acid (TBA) values of the shrimps and lamb loins were analysed after 0, 2 and 4 weeks of exposure. The odour of shrimps was evaluated with sensory evaluation using a multiple comparison test. Sensory evaluations of ice cream was conducted by trained panelists using a multiple comparison test. All the sensory evaluations were conducted after 2 and 4 weeks of exposure. In addition, ice cream was exposed to light under a yellow plastic film to find out the effects of riboflavin, which is known to operate as a sensitiser. After 4 weeks of exposure to the fluorescent light the total colour difference of the samples was higher than that of the products exposed to the LED light. Differences were pronounced especially in ice cream exposed to light under transparent film. The smell and taste of ice cream were affected when exposed to light under transparent or yellow plastic films. There were no statistically significant differences in the taste of ice cream when exposed to fluorescent or LED light for 4 weeks, but the smell of ice cream appeared to be more divergent from the reference when exposed to LED light under transparent film for 4 weeks than the smell of ice cream exposed to fluorescent light for 4 weeks. On the basis of this study, fluorescent light affected the colour of the frozen food more than LED light. Light sources did not differ from each other, when the results of the sensory evaluation of shrimps were considered. Because TBA values of lamb loins and shrimps also increased in reference samples, the effects of light could not be separated. Sensory properties of ice cream were affected by light exposures, but on the basis of sensory evaluation it is not possible to state which light source was more detrimental to the quality of ice cream.