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Effect of Vacuum Frying on Toxin Formation, Retention of Quality Attributes, and Consumer Acceptability as a Means to Eliminate Reconditioning After Long Term Cold Storage in White-, Red-, and Purple- Fleshed Potato Chips

Ms Christine Koestler, MS Candidate, Department of Food Science

Date and Location

When (Date/Time)

May 21, 2018, 10:00 AM - 11:00 AM

Where

252 Erickson Food Science Building

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Potatoes (Solanum tuberosum L.) are the largest fresh market vegetable crop in the United States. Americans consume, on average, 111.2 pounds/ person/ year with 17.8 pounds being consumed as potato chips. Color-fleshed potato chips are receiving more attention from consumers and producers as they are a rich source of phenolic compounds which have been shown to work as antioxidants, reduce the occurrence of certain cancers, and function as anti-inflammatory agents. In order to maintain a constant supply of potatoes year-round, potatoes are stored at low temperatures (2-10 °C). During cold storage, the starch in potatoes is converted to sugars. Accumulation of free reducing sugars produces more browning in fried potato products due to the Mallard reaction. To counter the accumulation of reducing sugars, potatoes are reconditioned at higher temperatures (15-20 °C) for up to three weeks prior to processing where as much as 80% of the reducing sugars are converted back to starch. Reconditioning is costly as it requires an additional storage room and additional energy input to maintain the controlled environment. Additionally, reconditioning causes a break in the cold-induced dormancy of potatoes which induces sprouting, resulting in a high economic loss. White-fleshed potatoes have been bred to withstand sprouting during reconditioning. However, color-fleshed potatoes have not, and are thus underutilized in potato processing.

Deep-fat (i.e., conventional) frying of potato chips at high temperatures increases the rate of the Maillard reaction resulting in the formation of toxins such as acrylamide, 5-hydroxymethylfurfural, and advanced glycation end-products. Therefore, there is a need to develop new technologies to reduce the formation of these toxic compounds.

This study investigated vacuum frying as an alternative processing technique to deep fat frying so that potatoes can be fried directly from cold storage, without reconditioning, which has the potential to remove the cost of reconditioning and reduce Maillard reaction products, all while maintaining chip quality parameters resulting in the production of an acceptable chip similar to a conventionally fried chip that has been reconditioned.

Vacuum frying (130 °C for 4.5 minutes) of Atlantic, Mountain Rose, and Purple Majesty potatoes, with and without reconditioning, produced chips that were more similar in color, texture, and moisture to commercially available samples, as compared to conventional fried (170 °C for 2.6 minutes), with and without reconditioning, as determined by industry used instrumental techniques. Acrylamide levels were found to be between 1,500-1,800 ppb (LD50 = 107 mg/kg). Reconditioning resulted in lower levels of acrylamide regardless of the frying method. However, vacuum frying led to higher levels of acrylamide than conventional frying regardless of the presence or absence of a reconditioning step. Conventional frying without reconditioning resulted in higher levels of 5-hydroxymethylfurfural as compared to conventional frying with reconditioning and vacuum frying with and without reconditioning, levels were found in the range of 20-125 ppb (LD50 = 2,500 mg/kg). 5-hydroxymethylfurfural values for vacuum frying, with and without reconditioning, were not statistically significant. Advanced glycation end-product concentrations were not statistically significant between samples and concentrations were found in the range of 20-30 ppb (LD50 = not reported).

In blinded sensory evaluations, consumers preferred chips that were vacuum fried without reconditioning over the conventional fried chips, with and without reconditioning. Additionally, consumers were willing to purchase colored chips at a higher price than white chips, once they were told that there was a potential health benefit associated with these chips.

The results of this study indicate that vacuum frying without reconditioning does not reduce the overall levels of toxins as expected which suggests that reconditioning is still necessary regardless of frying method. Even though vacuum frying did not lower the levels of toxins, the amounts found in the tested potato chips were all below levels of concern. Finally, consumer testing indicated that there was an overall preference for vacuum fried chips without reconditioning compared to conventional fried chips, with and without reconditioning. This indicates vacuum frying without reconditioning could be utilized as an alternative to conventional frying, either with or without reconditioning, to produce a high-quality chip.