Department of Food Engineering and Process Management, Faculty of Food Sciences, Warsaw University of Life Sciences, SGGW, 159c Nowoursynowska St, Warszawa, 02-776, Poland.
J Texture Stud. 2017 Apr;48(2):131-142. doi: 10.1111/jtxs.12224. Epub 2016 Sep 14.
The influence of the structure formed by the type of hydrocolloids (low-methoxyl pectin, the mixture of xanthan gum, and locust bean gum, and mixture of xanthan gum, and guar gum) and the aeration time (3, 5, 7, and 9 min) on textural properties of freeze-dried gels were investigated. The hardest texture generating the strongest acoustic emission was obtained by freeze-dried pectin gel, characterised by the lowest porosity and the largest pore diameter. Aeration time significantly affected mechanical and acoustic properties of the pectin gel lyophilisate. No effect of gel aeration time on tested characteristics of samples with mixture of hydrocolloids was observed. Strong positive correlations between acoustic energy as well as the maximum force and work and negative ones between porosity and pore diameter indicate that greater resilience and stronger acoustic emission of freeze-dried gels was caused by the reduction of porosity and the increase in the pore size of the material.
The research is expected to show the phenomenon of structure formation when preparing and freeze-drying gels and explain the influence of the process parameters (time of aeration, the type of hydrocolloids) on the formation of the internal structure and physical properties of a dried product, especially mechanical and acoustic properties. This achievement will contribute to the development of the science of food and human nutrition, especially within the context of the popular research on aerated diet products. The expected result will be the ability to develop a new technology for producing food with a delicate texture, using the phenomenon of sublimation. As a result, designing changes in the structure of freeze-dried fruit gels with a delicate structure will be possible due to the choice of ingredients and aeration parameters in order to develop innovative food characterised by favorable nutritional, health and functional properties, which will be attractive for the consumers.
研究了由不同类型水胶体（低甲氧基果胶、黄原胶和槐豆胶混合物、黄原胶和瓜尔胶混合物）形成的结构以及通气时间（3、5、7 和 9 分钟）对冻干凝胶结构特性的影响。通过冷冻干燥果胶凝胶获得了产生最强声发射的最硬质地，其具有最低的孔隙率和最大的孔径。通气时间显著影响果胶凝胶冻干物的机械和声学特性。混合水胶体凝胶通气时间对样品测试特性无影响。声能和最大力与功与孔隙率呈强正相关，与孔径呈负相关，表明冻干凝胶的弹性恢复力和更强的声发射是由孔隙率降低和材料孔径增大引起的。
该研究有望展示在制备和冷冻干燥凝胶时的结构形成现象，并解释工艺参数（通气时间、水胶体类型）对干燥产品内部结构和物理性能形成的影响，特别是对机械和声学性能的影响。这一成果将有助于食品科学和人类营养科学的发展，尤其是在人们对充气饮食产品的研究背景下。预期的结果是能够利用升华现象开发出一种生产质地细腻的食品的新技术。因此，通过选择成分和通气参数，可以改变冻干水果凝胶的结构，从而开发出具有良好营养、健康和功能特性的创新食品，这将对消费者具有吸引力。
