The small-scale machine for making soft-serve ice cream using liquid nitrogen as a refrigerant

Autor: Yu-Yu Chou, 周祐宇
Rok vydání: 2016
Druh dokumentu: 學位論文 ; thesis
Popis: 104
The aim of this study was to set the model of home liquid nitrogen soft-serve ice cream machine which combined home, commercial ice cream machine and recently, liquid nitrogen churning mixer. Base on past soft-serve optimal formula, in these years more and more discussions on commercial liquid nitrogen ice cream formula for stabilizer whether it will be added or not. In the light of this, variety of objective detection, consumer acceptable testing and descriptive analysis were used to determine the optimum formula for liquid nitrogen soft-serve. It’s an application for direct heat exchange between liquid nitrogen and cream mixture in this device. There’re three methods : refrigerant buried before cream mixture adding, refrigerant injection under cream mixture, and test of refrigerant dropped in cream mixture. The only feasible one for churning freezing is the third. The design of stirring wing is falling into, 0.405、0.59、0.91, three kinds of inner/outer diameter ratio, and it’s ture that the longer width of diameter, the less ice crystal agglomeration on the edge side. So we design of d/D, 0.99, optimal scraped agitator, trying to find out the optimal churning condition in different liquid nitrogen dropping flow with 10g/2.5s、15g/3.7s、20g/4.5s、25g/6.3s、30g/7.7s around 4g/s per time at 150 rpm. There’s optimal dropping condition with 25g/5s per time before cream mixture frozen. And 20/5s～15g/3.7s per time after freezing. The experimental ice cream variable formulas according to references were skimmed milk powder (11%, 12%, 13%, 14%, w/w) as milk solids-not-fat, distilled monoglyceride (0.1%, 0.2%, 0.35%, 0.5%w/w) as emulsifier, and different kind of stabilizer, including locust bean gum (0.25%, 0.375%, 0.5%, w/w), sodium carboxymethyl cellulose (0.15%, 0.175%, 0.2%, w/w), and carrageenan–κ (0.01%, 0.02%, 0.03%, w/w). The mixtures were put in self-made liquid nitrogen churning freezer, and products like soft-serve were extracted by 1/2 inch tube.The most viscosity of product at specific temperature was 7.04×10⁵ (cps, at -4.5°C). Also, frozen warming thermal analysis on Freezing stage by freeze dryer, melting test at room temperature (25°C). First droplet time of 35g sample, melting liquid volume within 30 minute were determined by these formulas. Whether it’s added stabilizer in the optimal soft-serve ice cream mixing formula at different freezing rate or not, there’re rang of supercooling between -11.22 to -24.25, rang of ice crystal between 21.78 to 704.60 μm², rang of density between 0.74 to 0.93, rang of overrun ratio 16.37 to 42.68%, rang of L value between 87.27 to 91.50, a value between -3.48 to 9.71, b value between 8.45 to 15.97 in color measurement, and rang of hardness value on texture profile analyzer in their physical properties. As the result of consumer sensory evaluation for the soft-serve ice cream,the scores of the optimum sample in the aspects of taste texture, whole favor and purchase intention separately were 6.57, 6.30, 3.60 which were respectively higher than the others without liquid nitrogen or without stabilizer. Statistically,the optimum one in taste texture performed the significant difference of all and especially between liquid nitrogen group exclusive and inclusive of stabilizer.According to this result,it is necessary for liquid nitrogen ice cream to add stabilizer.Last but not least,as regard to the total power consumption, liquid nitrogen churning freezer usage was about 49~52% that of general soft-serve ice cream maker, KD-100, which could be taken as basis of the development of modern machines.This study furthermore will provide commercial appliance research and development unprecedented way.
Databáze: Networked Digital Library of Theses & Dissertations
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