IN VITRO ANTI-COLON CANCER ACTIVITY OF COLD STORED AND RECONDITIONED VACUUM VS. CONVENTIONALLY FRIED COLOR-FLESHED POTATO CHIPS
Open Access
- Author:
- Stewart, Lauriel Sylvana
- Graduate Program:
- Food Science
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- August 03, 2018
- Committee Members:
- Jairam K. P. Vanamala, Thesis Advisor/Co-Advisor
Ramaswamy C. Anantheswaran, Committee Member
Joshua D. Lambert, Committee Member - Keywords:
- Colon Cancer
Stem Cells
Vacuum Frying
Anthocyanins
Polyphenols
Reconditioning
Cold Storage
Folin-Ciocalteu Assay
pH Differential Assay
Resazurin Cell Viability
Caspase Glo 3/7
Conventional Frying
Atmospheric Frying
Color-Fleshed Potatoes
Purple Majesty Potatoes - Abstract:
- Potatoes (Solanum tuberosum, Solanaceae) are one of the most commonly consumed vegetable crops across the globe. In the past ten years, consumption of color-fleshed potatoes has increased significantly. Color-fleshed potatoes are rich in polyphenols and have up to eight times the antioxidant capacity of yellow- and white-fleshed potatoes. During commercial processing of potatoes for chipping, they are initially held at a temperature of 4-10 °C in cold storage. Before processing, these potatoes are reconditioned by storing them at a higher temperature (12-20 °C) to convert reducing sugars back to starch. The reconditioning step represents an additional cost. Colon cancer is the second leading cause of cancer-related deaths in the United States. Cancer stem cells (CSCs) are responsible for initiation and progression of tumors in a variety of cancers and understanding their development can assist researchers in methods to manipulate CSC cell growth. Studies have shown that some bioactive compounds present in plant-based foods can reduce the risk of colon cancer by targeting colon CSCs. I examined the efficacy of vacuum fried and conventionally fried color-fleshed purple (Purple Majesty) potato extracts to inhibit cell proliferation and promote apoptosis within colon CSC pathways. I hypothesized that: (1) Purple majesty potato chips vacuum fried for 4 mins at 120 °C would have significantly greater levels of polyphenols and greater cell inhibitory activity towards colon CSCs compared with chips conventionally fried for 2 min at 180 °C. (2) When looking at the effects of reconditioning, chips from potatoes that were reconditioned for 2-3 weeks would have a lower amount of polyphenols when compared to chips from potatoes that were not reconditioned. (3) When looking specifically at the interaction between reconditioning and frying, vacuum fried chips that were not reconditioned would have greater levels of polyphenols when compared with the other treatments. The Folin-Ciocalteu Assay and the pH Differential Method were used to quantify total phenolic content and total monomeric anthocyanin content, respectively. I used UPLC-MS to quantify select anthocyanins, and phenolic acids. The effect of potato chip extracts on colon CSCs viability and apoptosis was determined using the Resazurin Cell Viability Assay and the Caspase Glo 3/7 Assay, respectively. My results indicate that there was an interaction between reconditioning and frying in terms of their effects on the phenolic compounds in the chips. Conventionally fried chips had a greater amount of total phenolic content when compared with the vacuum fried chips and the reconditioned conventionally fried chips had the greatest amount of total phenolic content. In contrast, the vacuum fried chips had a greater amount of total monomeric anthocyanin content when compared with the conventionally fried samples, irrespective of reconditioning. In addition to these findings, I also determined that the levels of caffeic acid, malvidin, and pelargonidin were greater in the vacuum fried chips that were not reconditioned when compared with all other samples. I also observed that the levels of gallic acid and chlorogenic acid varied with treatment. Non-reconditioned conventionally fried samples had the greatest amount of gallic acid and reconditioned conventionally fried samples had the greatest amount of chlorogenic acid. Regarding anti-colon CSC activity, I found that non-reconditioned vacuum fried chips had the greatest anti-proliferative and pro-apoptotic effect on the colon CSCs. The non-reconditioned vacuum fried chips were hence more effective at targeting colon CSCs. These results indicate that vacuum frying can be used to eliminate the need for reconditioning which is a more cost-effective alternative for food manufacturers and it also contributes to an added health benefit by preserving more beneficial bioactive compounds. Further work needs to be done in order to determine if these same trends occur in vivo.