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Browsing by Subject "sitruunahappo"

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  • Erilaisten saostinaineiden soveltuvuus emulsiogeelin valmistukseen härkäpapuproteiinista 
    Rissanen, Janina (2020)
    Securing an adequate protein intake raises questions for the future, and various plant protein products have grown in popularity in recent years. Tofu is one of the most popular vegetable protein products due to its versatility. Also, its different structural types are appealing to consumers. One way to increase the value of other grain legumes closer to soybeans would be to develop a tofu analogue from them. Faba beans are potential for this purpose, as they can be cultivated under the northernmost conditions, they are as rich in protein like soybeans and the proteins within soybean and faba bean are similar in structure. This study complements research related to the gelation of faba bean proteins. The aim was to study how different coagulants, their contents and different faba bean protein contents in the emulsion affect the resulting gel structure. The gels produced by each coagulant were examined separately so that the variables, i.e., coagulant and protein contents, were given three different values. The protein content of the emulsion was either 6, 7 or 8% (w/v), and the contents of coagulants were as follows: transglutaminase (TG) 5, 25 or 50 U/g of protein, gluconodeltalactone (GDL) 0.3, 0.65 or 1%, citric acid 0.14, 0.16 or 0.18% and calcium sulphate (CaSO4 · 2 H2O) 0.5, 1 or 1.5% (w/w). The structures of the gels were compared based on the results of Texture Profile Analysis (TPA) and sensory observations, and in addition, the samples were examined for the interactions formed between the proteins. This was done by dissolving the gels in various solvents. Of the gels studied, the most different structure was produced by transglutaminase, which provided a solid-like gel structure at the highest content combined with the highest protein content in the emulsion. Its TPA value for hardness was the highest. The interactions between proteins also differed most when comparing the results of other gels to transglutaminase gels. A probable explanation for these results was the strong isopeptide bonds formed by TG. GDL, citric acid or calcium sulfate did not produce such a solid gel structure, but the structures of the samples were much softer, part almost liquid. The protein content had a statistically significant effect on the hardness of gels coagulated with TG and calcium sulfate, among others. The coagulant content also affected the results of the TPA measurements, but they had less effect than the protein content.
  • Pinnan vaalenemisen hallitseminen kuoritussa porkkanassa 
    Hyytiäinen, Heli (2021)
    Peeling of carrot removes the epidermis and some sub-epidermal tissue. The new outer layer of cells is damaged, and it causes leakage of cellular fluids. The peeled surface is replaced by a new protective layer which is white material. Surface whitening is most likely due to drying of the outer tissue, lignin synthesis, or decreased carotenoid levels during storage of the carrot. The aim of the dissertation was to find efficient processing methods for controlling the surface whitening of carrot. Controlling surface whitening is important because from a consumer perspective it is a sign of a loss of freshness. Efforts were made to control the discoloration of the carrot surface with help of enhanced polishing, acidity control and edible film. The processing methods were as follows: twice polished (A), three times polished (B), three times polished + citric acid (C), three times polished + edible film (D). After polishing all the samples were immersed in ozonated water (0,3 ppm, 4 min). The samples were packed in LDPE or OPP packages. The samples were stored for 16 days at temperature of +4–6 ̊ C. Quality changes of the samples were assessed by packaging gas content, surface pH, colour measurements, images, microscopic images, microbiological quality and sensory evaluation. Processing with citric acid (C) and edible film (D) slowed formation of white surface for up to seven days, after that the differences between the processing methods decreased so much that they could not be detected any more. Sensory evaluation was done after nine days of storage. The appearance of the fresh-cut carrots was least white when the processing method was D and packaging material LDPE. Off-flavours detected were most likely due to natural taste variation of carrots.

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