Shah Yash, Zhou Xu, Tang Juming, Takhar Pawan Singh
Department of Food Science and Human Nutrition, University of Illinois, Urbana-Champaign, Urbana, Illinois, USA.
Department of Industrial & Systems Engineering, University of Washington, Seattle, Washington, USA.
J Food Sci. 2025 Aug;90(8):e70441. doi: 10.1111/1750-3841.70441.
Fried foods have a widespread appeal worldwide, but consumers are cautious about their high-calorie density and oil content. We evaluated microwave frying (MF) at 2.45 and 5.8 GHz frequencies as potential alternatives to conventional frying (CF) to produce fried foods containing less oil. MF is expected to lead to higher magnitudes of pressure in the food matrix than CF, which can provide higher resistance to oil penetration into the food. Real-time temperature and pressure measured using fiber optic sensors showed that MF resulted in faster sample heating and generated higher internal pressure than CF. The peak sample temperature and internal gauge pressure were the highest for MF at 2.45 GHz (107.3°C, 24.9 kPa), followed by MF at 5.8 GHz (104.1°C, 20.8 kPa) and CF (100.5°C, 13.8 kPa). The results indicated that the microwaves were not completely attenuated while traveling through the bulk oil and could penetrate the French fries. Below a sample moisture content of 3 g/g solids, the oil content increased rapidly with reducing moisture content for CF; the increase in oil content was relatively slower for MF at 5.8 GHz and negligible for MF at 2.45 GHz. This indicated that MF is an effective substitute for CF to produce lower oil content French fries with similar endpoint moisture content. The stress relaxation data showed that MF at 5.8 GHz produced stiffer (crunchier) French fries, which could be due to the intense crust heating. PRACTICAL APPLICATIONS: The current study showed that microwave frying can reduce frying times and produce French fries with lower oil content than conventional frying. This can help the food industry reduce processing times and offer consumers healthier fried foods. The insights generated from this work can help design process optimization studies and guide the physics-based modeling of microwave frying.
油炸食品在全球范围内广受欢迎，但消费者对其高热量密度和含油量有所顾虑。我们评估了2.45吉赫兹和5.8吉赫兹频率下的微波油炸（MF）作为传统油炸（CF）的潜在替代方法，以生产含油量更低的油炸食品。预计MF在食品基质中产生的压力比CF更高，这可以为油渗入食品提供更高的阻力。使用光纤传感器测量的实时温度和压力表明，MF导致样品加热更快，并且比CF产生更高的内部压力。样品峰值温度和内部表压在2.45吉赫兹的MF时最高（107.3°C，24.9千帕），其次是5.8吉赫兹的MF（104.1°C，20.8千帕）和CF（100.5°C，13.8千帕）。结果表明，微波在穿过大量油时并未完全衰减，并且可以穿透薯条。在样品水分含量低于3克/克固体时，CF的含油量随着水分含量的降低而迅速增加；5.8吉赫兹的MF含油量增加相对较慢，而2.45吉赫兹的MF含油量增加可忽略不计。这表明MF是CF的有效替代品，可生产出具有相似最终水分含量但含油量更低的薯条。应力松弛数据表明，5.8吉赫兹的MF产生的薯条更硬（更脆），这可能是由于外皮强烈加热所致。实际应用：当前研究表明，微波油炸可以缩短油炸时间，并生产出比传统油炸含油量更低的薯条。这可以帮助食品行业减少加工时间，并为消费者提供更健康的油炸食品。这项工作产生的见解可以帮助设计工艺优化研究，并指导微波油炸的基于物理的建模。
