Lue-lue Huang

Studies on Decreasing Energy Consumption for a Freeze-Drying Process of Apple Slices

The shape, color, flavor, and rehydration capacity of freeze-dried (FD) products are all better than other dried products. However, the energy consumption during FD is very high, which limits the application of this drying method for common materials. In this article, microwave vacuum drying (MWVD) was applied before or after FD to decrease the energy consumption during FD. Moreover, energy consumption was divided into two parts: valid and invalid energy consumption. Apple slices were used as an example to calculate the saving percentage of invalid energy consumption by comparing combination drying with FD. Apple slices freeze dried for 8.28 h first and then dried by MWVD have the best appearance, with a savings of 39.20% in invalid energy consumption. But apple slices freeze dried for 6 h first followed by MWVD have the highest savings of invalid energy consumption, 54.02%, while still maintaining an acceptable appearance.

Trends in Development of Dried Vegetable Products as Snacks

Diverse types of vegetable snacks made using different drying methods are becoming increasingly commercially important for the food processing industry worldwide because they are also recognized as healthy for human consumption. Here we consider four aspects of drying snacks: unit operations currently used in the industry, novel or emerging methods with nontraditional means, combined (or hybrid) drying methods, and the quality changes during storage. Each drying method has its own advantages and limitations. Hybrid drying techniques are being developed to maximize the benefits of different drying techniques to produce better quality vegetable snacks that are attractive to the consumer. The merits and limitations of more than 10 drying techniques used for making dried vegetable snacks are discussed. Moreover, several new vegetables snacks dried using new drying methods are presented and discussed. A comprehensive review of the recent progress in production of dried vegetable snacks is presented and recommendations are made for future research.

Study of the optimisation of puffing characteristics of potato cubes by spouted bed drying enhanced with microwave

BACKGROUND In commercial deep-fat frying of potato chips, the oil content of the final products ranges from 35 to 45 g 100 g(-1) (wet basis). High-temperature frying may cause the formation of acrylamide, making the products unhealthy to the consumer. The aim of this research was to explore a new method, spouted bed microwave drying, to produce healthier puffed snack potato cubes as possible alternatives to oil-fried potato chips. The influence of drying conditions of the spouted bed microwave drying on puffing characteristics of potato cubes were studied and compared with the direct microwave and hot air drying method. RESULTS Tandem combination drying of microwave-enhanced spouted bed drying (MWSB) could achieve a good expansion ratio, breaking force and rehydration ratio. The puffing characteristics of potato cubes were significantly affected (P < 0.05) by moisture content before starting microwave power in spouted bed microwave drying, by microwave (MW) power, and by the original size of potato cubes. CONCLUSION The optimum processing parameters were the moisture content at the start of microwave power (60%), the size of potato cubes (10-12 mm), and microwave power (2-2.5 W g(-1))

Freeze Drying of Apple Slices with and without Application of Microwaves

In this study, Fuji apple slices were dehydrated using freeze drying (FD) combined with microwave assisted with vacuum drying (VMD). The optimal parameter for the diversion point of moisture content from FD to VMD process was at the moisture level of 21%, and for VMD the optimal parameter for vacuum pressure was at 9.15 kPa and microwave power density was at a level of 3.18 w/g. The results show that the two-step technique can significantly reduce total FD time required by up to 40%, while the nutritional value of the dried apple chips remained unchanged compared to FD used alone.

Effect of two drying methods on antioxidant activity and hypoglycemic action of polysaccharides in three cultivars of lychee pulp

ABSTRACT Effect of air drying and freeze drying on polysaccharides of lychee with three cultivars was determined in terms of polysaccharides yield, antioxidant capacity and hypoglycemic action. The results show that Guiwei lychee pulp had the highest crude polysaccharide yield among three lychees. However, Feizixiao lychee had the lowest EC50 concentration and the highest FRAP (Ferric reducing antioxidant power) value. Moreover, Guiwei lychees dried by air drying had the best effect for improving glucose tolerance of normal mice and diabetic mice. Three freeze dried lychees had no significant effect. The effect of air dried Guiwei samples on decreasing TG was the best and it was even better than dapagliflozin group. Only freeze-dried Guiwei lychee could significant decrease the TC content in blood among all lychee samples. In a word, Feizixiao lychees had the best antioxidant capacity and Guiwei lychees had the best hypoglycemic effect. Air drying was better drying method for lychee polysaccharides than freeze drying in this study.

Studies on Controlling Surface Accumulation of Glucose on Dehydrated Cabbage

Dehydrated cabbage pretreated with glucose before drying can easily become covered with a thin white film of glucose during storage due to glucose transfer from the inside to the surface. Lactose and high-maltose syrup were added as partial substitutes for glucose in the process of the pretreatment using glucose before drying. In both conditions, good results were obtained concerning extending the period needed for glucose accumulation on the surface of the dried product, particularly in the presence of high-maltose syrup. In this work, effects of blanching time and ambient relative humidity during storage on glucose accumulation were also studied. The results show that dehydrated cabbage blanched for 90s and stored in a low-humidity environment displays reduced glucose accumulation on the surface of the products and extends the accumulation time without reducing glucose content from 12 days to 28 days.