| Factors contributing to potato chip color, flavor and texture were evaluated. A novel vacuum distillation method was developed to extract, concentrate, and analyze pyrazines from potato chips using solid phase microextraction and GC-MS. Ten new pyrazines were identified in potato chips, of which 2,5-dimethyl-3-ethyl pyrazine and 3,5-diethyl-2-methyl pyrazine were significant contributors to total pyrazine yield. Pyrazine formation was monitored in two model systems using potato slices that were infiltrated with reducing sugars (RS) and amides and then fried. The first model evaluated pyrazines produced by the reaction of RS, asparagine (Asn) and glutamine (Gln), individually and as a mixture. Similar pyrazines were formed for both amides, but varied in concentration. The amide mixture resulted in lower pyrazine yields than were predicted from the individual amides, which indicated competition for the available RS. Models containing Glu were found to have decreased hue angles, indicating increased browning. The second model evaluated the pyrazines formed from increasing concentrations of Asn and Gln (0--1.5% FW), and RS (0--0.32% FW) in a full factorial design to simulate metabolic changes in raw potatoes during long term storage. Increasing RS concentrations enhanced the yield of the predominant pyrazines, confirming their importance to potato chip flavor. Pyrazine concentrations were not significantly affected by high amide content at low RS levels (<0.08% FW), however at higher reducing sugar levels (0.16 and 0.32% FW) the amino acid levels impacted the yields of the most abundant potato chip pyrazines, which could have a negative effect on flavor. Lastly, whole potatoes of similar size and specific gravity were preheated in water to determine optimum conditions for improving the texture of fried chips. The core temperature of the potatoes was limited to <55°C to prevent starch gelation, and optimum time and temperature combinations were determined. The preheating conditions were then evaluated on potatoes of three size and specific gravity categories. Potato chips were analyzed for instrumental and sensory texture, color, and oil content. Instrumental and sensory texture attributes were related (r = 0.67) but preheating treatments did not affect color or oil uptake, which were solely attributed to raw potato size and specific gravity. |
