Kathryn Gause

Date of Award

8-2014

Level of Access Assigned by Author

Campus-Only Thesis

Degree Name

Master of Science (MS)

Department

Plant, Soil, and Environmental Sciences

Advisor

Gregory Porter

Second Committee Member

Lewis Brian Perkins

Third Committee Member

Mary Ellen Camire

Abstract

Nutrient management can affect tuber biochemistry and processing quality, which in turn can play a role in the acrylamide concentration of processed potato products. Adoption of new potato varieties and careful nutrient management programs may help the potato industry minimize the risk posed by acrylamide formation during processing. The objectives of this project are to explore whether reduced rates of N and K fertilizer can help decrease the levels of acrylamide in fried potatoes while also maintaining yield, tuber size, and other quality attributes needed for processing. The industry standard potato variety, Russet Burbank, was compared to two promising new processing clones, Easton and AF3362-1. Three levels (0, 168, 336 kg/ha) of K fertilizer and three levels (0, 134, 268 kg/ha) of N fertilizer were applied at planting. Yield, tuber size, and specific gravity were determined at harvest. Tubers from 10°C storage were tested for fry quality and analyzed for the acrylamide precursors, asparagine and reducing sugars. Sucrose, lysine, tyrosine, and phenolic compounds, phytochemicals with the potential human health benefits, were also measured.

Acrylamide formation in French fries was driven by reducing sugar concentrations in this study, rather than increased concentrations of amino acids or phenolic compounds. The results of this research show that fry color, percent fries with non-uniform color, fructose concentration, and total reducing sugar concentrations were positively correlated with acrylamide concentration of French fries. Asparagine, tyrosine, lysine, chlorogenic acid, and caffeic acid concentrations were not significantly related to acrylamide formation in this study. N and K fertilizer rates significantly increased yield and tuber size and decreased specific gravity during both years. Hollow heart incidence decreased with increasing N and K. Acrylamide concentration in fries increased with increasing N in this study; however, the change in acrylamide concentration resulting from increasing the N rate from 134 to 268 kg ha-1 was very small. K rate did not affect acrylamide formation or fry color. N rate did not strongly affect fry color in this study, nor did it significantly affect tuber fructose, total reducing sugar, or amino acid concentrations, although increasing N rates did result in increased tuber glucose and total phenolic concentrations and decreased tuber chlorogenic acid and caffeic acid concentrations during one of two years.

Potato varieties differed in biochemical constituents; including reducing sugars, asparagine, and phenolic compounds and greatly affected the acrylamide concentration of French fries. Russet Burbank consistently had the highest acrylamide concentration in fries, highest reducing sugar concentrations, and darkest fry color. Easton was lowest in acrylamide concentration in fries, had the lowest reducing sugar concentrations, the lightest fry color, and the highest yields of the varieties in this study.

This experiment was able to tie consumer needs to grower practices. Based on this research, 134 kg N ha-1 and 168 kg K2O ha-1 were the best fertilizer rates for balancing tuber yields with a range of tuber quality attributes, including acrylamide- forming potential. Future research could be designed to more completely explore nutrient, storage and other management approaches to reduce acrylamide-forming potential and continue to produce a healthier French fry. Adoption of new processing varieties, such as Easton and AF3362-1, would result in lower acrylamide French fries, better disease resistance, reduced defect percentages and higher yields.

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