Date of Award


Document Type


Degree Name

Master of Science (MS)


Food Science and Human Nutrition

Committee Member

Dr. John McGregor, Committee Chair

Committee Member

Dr. Xiuping Jiang

Committee Member

Dr. Julie Northcutt

Committee Member

Mrs. Sara Cothran


Food allergies are a serious and growing problem in developed countries. Allergen cross-contact at foodservice establishments is a common cause of food allergic reactions. Therefore, this study sought to determine if dipper wells used in ice cream scoop shops pose a relevant risk to food allergy sufferers. First, a matrix study was conducted to evaluate if peanut detection by real-time PCR was inhibited by the ice cream matrix, as fat and proteins are known PCR inhibitors. Frozen ice cream, liquid ice cream mix, and water matrices were tested. Second, a controlled time trial was conducted to evaluate the efficacy of allergen removal in ice cream dipper well water. Peanut butter ice cream was added to a dipper well and water samples were collected at various rinse times. A continuous use scenario and two dipper well basin cleaning techniques were also evaluated. Finally, a survey of ice cream scoop shop owners was conducted to collect relevant information regarding current dipper well practices and policies. Results of the matrix study showed low peanut recovery in all matrices, with recovery rates of 23.9%, 17.7%, and 6.2% in frozen ice cream, liquid ice cream mix, and water matrices, respectively. The recovery rate of plain peanut butter was 5.6%. PCR inhibitors, the physio-chemical properties of ice cream, and the PCR extraction and quantification kit were all believed to be factors in the recovery rate. Based on these results, we recommend using a DNA extraction technique designed specifically for fatty food matrices for future peanut butter sample analysis, and either a matrix-calibrated or a matrix-independent PCR system for future ice cream sample analysis. Results of the controlled time trial showed that peanut removal followed an exponential decay pattern. Quantitative results showed that while it is possible for peanut levels to be above the threshold dose, it is extremely unlikely. Dipper well basin cleaning techniques were not able to remove all traces of allergens, so more robust cleaning procedures are necessary to deal with high loads of allergens. Results of the survey showed that while most ice cream scoop shop owners had a good understanding of allergen cross-contact, advisory allergen signs were not prevalent in ice cream scoop shops. We conclude that ice cream dipper wells do not pose a significant risk to food-allergic consumers, but as a precaution for a worst case scenario, we recommend that ice cream scoop shops post allergen advisory signs and avoid using scoops from the dipper well to serve customers with a food allergy.



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