Study On The Technology Of Vacuum Frying For The Breaded Shrimp

Breaded shrimp is one of the most important deep-processing shrimp products andis welcomed by consumers due to its beautiful appearance, unique flavor and texture.The batter’s ingredients and frying technology are the key influencing factors. Numerousstudies have revealed that fried breaded shrimps produced by using present batter’singredients and traditional frying method contain large amounts of fat, which may beharmful to human health. In order to decrease the oil absorption of the breaded shrimp,improve its qualities, and prolong its shelf-life, influences of the addition of soy proteinisolate and gums in the batters on qualities of atmospheric fried breaded shrimp werestudied. Then, breaded shrimp products were produced by means of vacuum fryingtechnology, and the qualities of the product were discussed. In addition, packagingmethods and storage conditions of vacuum fried breaded shrimps were researched.The effects of soy protein isolate (SPI), guar and tamarind gums addition to thewheat flour-based batter on the qualities of atmospheric fried breaded shrimps wereevaluated. The coating pick-up, moisture loss, oil absorption, color, texture and sensoryattributes of the samples were determined. The results showed that SPI, guar andtamarind gums addition to the batters increased the coating pick-up of breaded shrimp,reduced moisture loss and oil absorption of atmospheric fried breaded shrimps withbetter brittleness. Compared with the atmospheric fried breaded shrimp added guar andtamarind gums, the samples added8g SPI to the batter provided the best texture propertyand highest sensory score with lowest oil content and without color degradation. Theoptimum formula of batters containing92%wheat flour,8%SPI,10%sugar and5%saltwas selected.Then the effects of vacuum frying on qualities of breaded shrimps were researched.The effects of oil temperature and frying time on the moisture loss, oil uptake,acrylamide content, texture and color of vacuum fried breaded shrimps were investigated.In addition, the experiment data measured about moisture content and oil absorption ofbreaded shrimps during vacuum frying were simulated. The results showed that changesof moisture loss and oil absorption could accurately be described by the exponentialmodel and the first order kinetic equation, respectively. The moisture loss and oil absorption of vacuum fried breaded shrimps were significantly (p <0.05) lower than theones obtained under traditional conditions. The moisture loss and oil absorption ofbreaded shrimps during vacuum frying increased with the increasing temperature andtime, but no significant difference was found (p>0.05). After ten minutes of frying, themoisture content and oil content of breaded shrimps fried at80,100and120℃undervacuum conditions were0.465±0.004,0.453±0.013and0.429±0.014gwater/gwet basis,and0.20±0.013,0.23±0.012and0.24±0.019goil/gdry solid, respectively, while the onesobtained under traditional condition (170℃) were0.306±0.010gwater/gwet basisand0.316±0.003goil/gdry solid, respectively. According to the results measured about texture andcolor, breaded shrimps with desirable color and lower hardness could be produced byusing vacuum frying technique. What’s more, vacuum frying could effectively decreasethe acrylamide content of breaded shrimps (p <0.05). The quality of breaded shrimpsproduced by vacuum frying at100℃for8min is the best.In order to discuss the shelf-life of vacuum fried breaded shrimps, influences ofModified Atmosphere Packaging (MAP) consisting of different packaging materials(polyethylene bag and Aluminum Foil bag) and different gas proportions (100%N2,30%CO2and70%N2,70%CO2and30%N2, and100%CO2) on the total viable count(TVC), total volatile basic nitrogen (T-VBN) value, acid value and sensory quality ofvacuum fried breaded shrimps were discussed during storage at room temperature in thispaper. The results showed that the packaging method for MAP, which consists of theAluminum Foil bag and gas proportions70%CO2and30%N2, is the optimum.Then the total viable count (TVC), total volatile basic nitrogen (T-VBN) value, acidvalue and sensory quality of vacuum fried breaded shrimps were measured duringstorage at different temperatures in this paper. In addition, the experiment data obtainedwere simulated by using the first order kinetics equation and Arrhenius equation. Theresults indicated that changes of T-VBN value fitted the first order kinetics equation best.The kinetics equation for the shelf-life of vacuum fried breaded shrimps wasSL=2.11×10-5e0.004/Tand the shelf-life of vacuum fried breaded shrimps at4,15and25℃was38.0,21.9and13.8days, respectively.