IMPINGEMENT DRYING OF POTATO CHIPS

The effect of superheated steam temperature (115, 130, and 145C) and convective heat transfer coefficient (100 and 160 W/m²C) on the drying rate and product quality attributes (shrinkage, density, porosity, color, texture, and nutrition loss) of potato chips was investigated. Furthermore, potato chips dried by impinging superheated steam (130 and 145C, h = 100 W/m²C) were compared to air dried (same conditions), commercial, and fried potato chips. Temperature and convective heat transfer coefficient had a significant effect on the drying rate during superheated steam impingement drying. Potato chips dried at higher drying temperature and convective heat transfer coefficient showed less shrinkage, lower bulk density, higher porosity, and darker color when compared to chips dried at lower temperatures and convective heat transfer coefficients. They were also less hard and had a lower vitamin C content. A higher rate of evaporation during the falling rate period was obtained when superheated steam drying was compared to air impingement drying. Potato chips produced using superheated steam impingement drying showed more shrinkage, higher bulk density, lower porosity, and lighter color than chips dried with air under the same temperature and with the same convective heat transfer coefficient (130, and 145C, h = 100 W/m²C). Moreover, superheated steam‐dried potato chips retained more vitamin C during the drying process.     

MICROWAVE and CONVECTIVE DRYING of POTATO SLICES

Potato slices were dried using microwave drying, combined microwave and convective drying, and convective drying. Rehydration kinetics were also studied. Drying rates of the different drying methods were determined and microwave drying was compared with convective drying. Microwave drying has a potential for producing better quality dried products while considerably reducing drying duration (i.e., 10 min vs. 10 h). Effective moisture diffusivity profiles were calculated using Fick's diffusion model in one dimension. Statistical analysis showed diffusivity to increase with increasing internal temperature but to decrease (in microwave drying) with increasing moisture content, with high correlation (R²≥ 0.973).     

节能型微波干燥马铃薯片的特性研究

通过对微波干燥马铃薯片的特性研究，得出了在微波干燥条件下马铃薯片的失水及耗电特性。并在此基础上，得出了各指标的回归方程，从而对各参数进行了优化设计，得出了各参数的最佳组合。     

EVALUATION OF OLEIC SAFFLOWER OIL IN FRYING OF POTATO CHIPS

SUMMARY– A recently introduced variety of safflower, UC-1, produces an oil in which oleic:linoleic acid ratios of ordinary safflower oil are reversed, giving an oil with iodine value 90. This oil was compared with cottonseed oil and hydrogenated vegetable oil (HVD) for frying potato chips. After accelerated storage at ambient temperature under fluorescent light, the quality of chips fried in oleic safflower oil was ranked equal to that of chips fried in hydrogenated oil, Chips fried in either oil were more stable than those fried in cottonseed oil. Effect of propyl gallate antioxidant was negligible.     

MICROWAVE FREEZE DRYING

A critical review of recent work in microwave freeze drying of food products is presented. This is followed by a general evaluation and recommendation for future work. The major technical problems that would prevent commercial use of microwave freeze drying have been solved. Economic studies show that processing costs for microwave freeze drying are lower than the costs for conventional freeze drying. Thus there has been adequate research and development for commercialization. A discussion is presented for improving the transfer of technology to aid commercialization. Recommendations are made for additional research and development.     

KINETICS OF ACRYLAMIDE FORMATION DURING TRADITIONAL AND VACUUM FRYING OF POTATO CHIPS

Acrylamide is considered a carcinogen in animals and a possible carcinogen in humans. It has been found in starch‐rich foods cooked at high temperatures. Vacuum frying (10 Torr) was investigated as a possible alternative to reduce acrylamide formation in potato chips. The cultivar Atlantic was used to determine the kinetics of acrylamide formation during traditional and vacuum frying at different temperatures. There was a 94% decrease in acrylamide content when potatoes were fried to the same final moisture content (1.5% ± 0.3% w.b.) under vacuum compared to those fried under atmospheric conditions. Acrylamide accumulation under vacuum frying was modeled using first‐order kinetics (during traditional frying, the logistic kinetic model was used). The behavior of the kinetics of acrylamide content in potato chips fried under the two processes was different mainly because of the different temperatures used. During traditional frying, higher temperatures are used (150 to 180C) and acrylamide after some time is produced but starts degrading, producing a constant level of acrylamide content at longer times. During vacuum frying (10 Torr), acrylamide increased exponentially (but at lower levels) for all frying times.     

微波干燥在亚麻纺织工业的应用

介绍了微波干燥的原理和主要特点,研究了利用微波干燥亚麻纱管的工艺,探讨了微波辐射时间、微波功率对亚麻纱管脱水率的影响,考察了工业微波干燥机的干燥能力,并将实验结果与传统烘房干燥后亚麻纱的色差和断裂强度进行了比较。     

RELATIONSHIP BETWEEN INSTRUMENTAL AND SENSORY ANALYSIS OF TEXTURE AND COLOR OF POTATO CHIPS

The instrumental and sensory analysis of the texture and color of commercial potato chips were compared. The instrumental measurement was a puncture test with an Intron Universal Testing Machine, and the parameters used were fracture force, deformation and stiffness. The instrumental color quantification was a computerized video image analysis technique, and the color was expressed as L*a*b* values. Sensory evaluation of texture and color was performed by a sensory panel especially trained in evaluating potato chips. The sensory attributes were "hardness", "chewiness", "crunchiness", and "tenderness" for texture analysis, and "yellow color", "burnt aspect", "sugar colored aspect" and "transparency" for color analysis. The factor analysis of the sensory attributes indicated that texture can be divided into two principal components, one represented by "hardness", "crunchiness" and "chewiness", and the other by "tenderness" alone. The factor analysis of the color can be divided into two principal components, one including "yellow color" and "burnt aspect", and the other "sugar colored aspect" and "transparency". Discriminant analysis showed that "tenderness" and "crunchiness" could predict correctly over 90% of the data. Fracture force correlated well with all of the sensory attributes (R² > 0.76), and L* with the sensory color attributes (R² > 0.79). The "Tenderness" was the individual sensory attribute which had the highest correlation (R²= 0.95) with fracture force.