Silva-Espinoza Marilú Andrea, Camacho María Del Mar, Martínez-Monzó Javier, Martínez-Navarrete Nuria
Food Investigation and Innovation Group, Food Technology Department, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
Foods. 2021 Nov 10;10(11):2756. doi: 10.3390/foods10112756.
Nowadays, the consumer is looking for healthier, more attractive, ready-to-eat, and safer foodstuffs than fresh products. Despite freeze drying being known for providing high added value products, it is a slow process which is conducted at low pressures, so, in terms of energy consumption, it turns out to be quite costly for the food industry. With the purpose of obtaining a freeze-dried orange puree, previously formulated with gum Arabic and bamboo fiber, which can be offered to consumers as a snack at a low economic cost, the impact of the process conditions on energy consumption has been considered. The product temperature evolution and the energy consumption were registered during the drying of frozen samples at different combinations of chamber pressures (5 and 100 Pa) and shelf temperatures (30, 40 and 50 °C). In each case, the time processing was adapted in order to obtain a product with a water content under 5 g water/100 g product. In this study, the secondary drying stage was considered to start when the product reached the shelf temperature and both the pressure and the temperature affected the duration of primary and secondary drying stages. The results obtained led to the conclusion that the shorter duration of the process when working at 50 °C results in significant energy saving. Working at a lower pressure also contributes to a shortening of the drying time, thus reducing the energy consumption: the lower the temperature, the more marked the effect of the pressure.
如今，消费者正在寻找比新鲜产品更健康、更具吸引力、即食且更安全的食品。尽管冷冻干燥以提供高附加值产品而闻名，但它是一个在低压下进行的缓慢过程，因此，就能源消耗而言，对食品工业来说成本相当高。为了获得一种预先用阿拉伯胶和竹纤维配制的冷冻干燥橙汁泥，并能以较低的经济成本作为零食提供给消费者，研究了工艺条件对能源消耗的影响。在不同的腔室压力（5和100帕）和搁板温度（30、40和50℃）组合下对冷冻样品进行干燥时，记录了产品温度的变化和能源消耗。在每种情况下，调整处理时间以获得水分含量低于5克水/100克产品的产品。在本研究中，当产品达到搁板温度时，认为二次干燥阶段开始，压力和温度都会影响一次和二次干燥阶段的持续时间。所得结果得出结论，在50℃下工作时，较短的工艺持续时间可显著节省能源。在较低压力下工作也有助于缩短干燥时间，从而降低能源消耗：温度越低，压力的影响越明显。
