| Nowadays, the most of potato chips sold in the market in our country are producedby traditional deep-fry technique, which have two disadvantages, one is the high oilcontent arrived at 35.3％to 44.5％, the other is the short shelf-life due to the high oilcontent. Therefore, it is necessary to find a new processing technology decreasing theoil content of potato chips. At meantime, the traditional deep-fry technique is stricteron choosing raw potato tubers, which are required low content of reducing sugars andhigh content of dry material. But there are not enough eligible special varieties forprocessing potato chips. So we should discuss a new technology to widen the range ofchoosing varieties for processing potato chips. With coating or spraying oil combinedmicrowave baking, we produced low oil content potato chips whose overall qualitieswere the same as that produced by traditional deep-fry technique. The main resultswere summarized as following:1 Study on characteristics of microwave drying of sliced potatoIn order to understand the behaviors of sliced potato in microwave drying so as toprovide basic data for practical design, the sliced potatoes of thickness ranging from1.2mm to 2.0mm were selected as samples and the drying tests were carried out atmicrowave power levels from 9.6W/g～16W/g. Also, the temperature and moisturechanges were solved. It indicates that the sliced potatoes experience three periodsduring drying: a preheating period with only small amount of moisture removed, anisothermal period in which most moisture loses and food temperature depends on themicrowave power level and sample thickness, and a final period with drying ratedropping off and temperature rising rapidly. Under the same microwave power levelcondition, the drying rate was not related with the sample thickness. When the sample-s had the same thickness, microwave power mainly controlled drying rate andtemperature of the products. The higher microwave power was, the shorter dryingtime had. During the final period with drying rate dropping off and temperature risingrapidly, reducing the microwave power can avoid deterioration of the product'squality due to the high temperature. During microwave drying, taking the method thatcombined with the hot air drying or far-infrared drying can improve the quality ofpotato chips.2 Discussion on the Conditions of Microwave Techniques Producing Low OilContent Potato ChipsThe obiective of this work was to determine the effect of some treatments over the quality of products (crispness, color and oil content) during producing low oil contentpotato chips by microwave baking. The trials indicated that we could decrease the oilcontent of potato chips by microwave baking (the oil content below 20％), and thepre-drying treatment after blanching (air-dry temperature 85℃, air-dry time 30 min～35min),immersion in salty water prior to pre-drying treatment (1.5％～2.0％concentration of salty water, immersion time 5 min), and covering with soy milkpowder on the surface of potato chips before basting all could decrease the oil contentof potato chips and increase their crispness. At meantime, covering with a properdosage of soy milk powder could give potato chips favorable color. The right dosageof soy milk powder was at 4％～6％. However, freezing treatment prior to pre-dryingtreatment darkened products' color and showed a slight effect on crispness or oilcontent.3 Study on the Optimum Parameters of Microwave Techniques Producing Low OilContent Potato ChipsAccording to the results of single element experiment, we chose four elementssuch as potato variety, pre-drying time, concentration of salty water and coveringdosages to design L12(31×24) orthogonal experiment. By the experiment we got themicrowave products and compared with the products produced by traditional deep-frytechnique. The results show that potato chips produced by microwave contain oilbelow 12％, whose crispness degree and acrylamide content are at the same levelscompared with the potato chips produced by traditional deep-fry technique. The coloris better than the latter. Its peroxide Value and acid value are in the permission area ofcountry standard. It belongs to safe food. With microwave baking, although the potatochips qualities are influenced by the potatoes' varieties (the Favorite quality is the bestin this paper), potato chips from a variety of potato at will with microwave bakingexcel over the potato chips produced by traditional deep-fry technique. The power ofmicrowave and baking time both influence the quality of potato chips. Therefore,choosing higher power at first and lower power later can improve the integrate qualityof potato chips.Through the experiment, the result shows the optimum techniqueparameters in the microwave baking. That is choosing the best variety (Favorite),peeling off and slicing 1.2mm, immediately washing it with cold water, blanching1.5min at boil water, then dipping in 1.5％salty water 5 min,heated-air drying 30minat 85℃, swathing it with 4％soy milk powder, basting and baking with microwave.The microwave power contains pre-power and after-power. They are separately 800Wand 480 W. The baking time is 2 min at each power.
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