Characterization of baked potato strips processed in a Radiant Wall Oven
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A Radiant Wall Oven (RWO) was used to produce potato strips with lower fat content while maintaining the similar quality to deep-fat fried product. Frozen par-fried potato strips purchased from commercial supplier were sorted and cut to have 5 x 1 x 1 cm3 dimensions, and baked in a RWO at temperatures of 290 – 365 °C with different processing times. Radiant, natural convective and overall heat transfer coefficients were determined for each RWO treatment by experimentally monitoring temperature and heat flux. Cutting force, puncture force, lightness, chroma and hue, moisture and fat contents of the RWO-baked potato strips were measured and compared to that of deep-fat fried samples (177 °C for 3 min). Correlation between heat transfer parameters and quality characteristics of the samples were also determined. The time-temperature treatment was used to develop a severity parameter to predict the quality characteristics of RWO-baked potato strips. Instrumental and trained panel sensory assessment of texture of the potato strips indicated that RWO-baked strips at 365 °C for 6.5 min had similar texture as deep-fat fried potato strips, yet contained 81.5% less fat. However, those potato strips were lighter and less brown in color, and had 18% more moisture than the deep-fat fried potato strips. Consumer acceptability of RWO-baked potato strips was 65.7% before and 85.7% after revealing the Nutrition Facts. Both were lower than the acceptability of deep-fat fried samples. However, 36.5% of consumers were willing to purchase RWO-baked samples. To reduce the processing time, heating by steam processing for 75 s or 90 s was used prior to potato strips were baked in RWO oven at temperatures of 450 – 550 °C for 1.5 – 3.5 min. Based on the instrumental and sensory analysis, RWO processing at 500 °C for 3 min after steam processing for 90 s resulted in the baked potato strips most similar to the control samples. Finally, a 41-member consumer panel indicated 51.2% acceptability and 35% willingness to purchase the RWO-baked pre-cooked potato strips. Even though RWO-baked potato strips needed improvement, consumers were willing to compromise sensory quality for calorie reduction in potato strips.