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Colored Potato Bioactive Compounds as Anti-Obesity Agents

Bunning, Marisa; Vanamala, Jairam
Colorado State University
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The overall goal of this integrated project is to identify consumer-preferred colored potato varieties with high content of putative anti-obesity bioactive compounds, and appropriate storage and processing methods that have minimal effects on the content, composition, bioavailability and "lean gut microbiota" promoting ability in pigs (an agriculturally important animals)consuming a high-fat diet, and to communicate research finding through a mechanism that results in technology and knowledge transfer to appropriate stakeholders.

Project Objectives: 1. Identify elite colored/specialty potato cultivars with desirable agronomic parameters and health benefiting bioactive compounds: Six specialty potato cultivars (three yellow and three purple) will be analyzed for drought, pest and disease resistance, length of growing season, specific gravity, storability, tuber size, and yield, and the content of bioactive compounds as compared to the commercial white potato variety Atlantic.

2. Determine the effect of storage and processing (baking and chipping) on antioxidant capacity, phenolic and acrylamide content and sensory properties of colored potato cultivars. Fresh and processed (baked vs. chipped) tubers will be analyzed for antioxidant capacity, phenolic and acrylamide (a potential human carcinogen at higher doses) content. Baked and chipped samples will be analyzed for appearance, color, taste, crispiness and overall acceptability, as compared to the commercial white variety Atlantic using sensory analysis.

3. Determine the extent to which raw vs. processed potato bioactive compounds differ in their alteration of Bacteroidetes-rich "lean microbiota" or Firmicutes-rich "obese microbiota" in the gut of obese pig. One of the current funded grants (USDA NRI Integrated Grant, 2009-55200-05197) provides the fecal samples from obese pigs fed with processed purple and yellow potatoes. These fecal samples will be analyzed for lean (Bifidobacterium and Lactobacillus) and obese (Staphylococci and Clostridia) microbiota using media exclusion and fluorescence in situ hybridization (FISH) techniques. Ratio of lean vs. obese gut microbiota will be correlated with back fat thickness, lipogenesis and lipolysis measured in the obese pig as part of the funded USDA grant.

4. (a) Translate the knowledge obtained from agronomic practices, food processing operations, phytonutrient analyses, and functional studies (lean vs. obese microbiota in relation to lipolysis vs. lipogenesis) into an Extension program to educate producers,consumers and food industry partners in Colorado. Information will be shared with Colorado producers at field days, consumers and industry partners via workshops, and CSU Extension website to increase the knowledge on colored potato selections, appropriate processing methods and health benefits, and food safety issues related to acrylamide. (b) Survey the effectiveness of various dissemination methods and the impact of the research on the horticultural, post-harvest and processing practices and methods employed towards utilization of specialty potatoes.

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NON-TECHNICAL SUMMARY: An effective strategy to combat the growing threat of childhood obesity includes a combination of dietary, lifestyle, educational, environmental, behavioral and policy changes. Emerging evidence suggests that diet plays an important role in pathophysiology of childhood obesity. Functional foods with putative anti-obesity properties marketed today are expensive, thus, it is imperative to develop evidence-based functional foods that are affordable to low income consumers susceptible to obesity. The potato (Solanum tuberosum L.) is the world's 3rd-largest food crop and the leading vegetable crop in the United States, with per capita consumption of about 126 lbs annually. In recent years, demand for specialty potatoes has risen sharply in developed countries and the United States, in particular. Due to their health benefiting properties, specialty and/or colored potatoes represent one mechanism for enhancing human nutrition through popular and palatable means. Colored potatoes are rich in anti-oxidant and anti-obesity bioactive plant compounds, such as carotenoids, and anthocyanins. However, potatoes are stored and processed before consumption and the effect of storage and processing on the health benefitting properties of specialty potatoes is not known. For producers and consumers to fully benefit from these properties, it is imperative to document the specific mechanisms of action of the protective foods and to understand the effects of post-harvest storage and processing methods on the biological activity of the functional compounds found in specialty potatoes. To address the above need for research, we propose to determine the effect of post-harvest treatments (fresh vs. stored potato) and processing methods (baking vs. frying) on the total phenolic and acrylamide content and antioxidant capacity. We will also determine the extent to which raw and processed potato carotenoids and anthocyanins differ in their alteration of Bacteroidetes-rich "lean microbiota" or Firmicutes-rich "obese microbiota" in the gut of obese pig. Obesity is associated with higher proportion Firmicutes, and lower proportion of Bacteroidetes, and reduced diversity. To answer these research questions we will utilize samples collected from pigs provided with high-fat diet for two months followed by high-fat diets containing either fresh, baked or fried potatoes for 6 weeks. Research findings will be communicated through a variety of mechanisms that results in greater technology and knowledge transfer to stakeholders including consumers, potato producers and processors.

APPROACH: While the overarching goal of this research is to understand the role of post-harvest and processing effects on bioavailability and "lean gut microbiota" promoting ability, we also aim to communicate research results to appropriate stakeholders so that they may incorporate findings into their production practices and marketing plans. The research component of the proposal provides the first insight into postharvest handling and processing (baking and frying) effects on the phenolic, acrylamide content and antioxidant capacity using spectrophotometric and HPLC One of the current funded grants (USDA NRI Integrated Grant, 2009-55200-05197) provide the fecal samples from obese pigs fed with processed purple and yellow potatoes. In brief, the experimental design of funded USDA grant is; seventy two castrated male pigs will be housed individually and fed a standard (control) diet (10 pigs) or high-fat diet (62 pigs) for 8 wk. At the end of the 8 wk, 56 pigs from high-fat diet group and eight pigs from standard diet group will be selected for the experimental diet intervention. Eight pigs on standard diet continue on standard diet for an additional 9 weeks. Fifty six pigs on high-fat diet will be assigned to one of seven dietary treatment groups (n = 8): (1) chow diet; (2) yellow potato at y % that is (a) baked and (b) raw (freeze-dried); (3) purple potato chip at p % that is (a) fried and (b) raw; (4) white raw potato at y % or p % (whichever is higher); and (5) y % yellow baked + p % purple fried potato. The percentage dietary concentration of potato (y % and p %) will be decided based on the results of the dose-response study (conducted in summer 2010). Feed allowance will be 90% of voluntary feed intake observed from the dose-response study to ensure all pigs consume similar amounts of feed during the 9wk experimental period. Fresh urine and fecal samples will be collected after experimental diet intervention at wk 0, 2, 4, 6, 7, 8 and 9 of the study. Fresh fecal samples will be plated in triplicate on a variety of differentially-selective media (e.g. genus-specific) and incubated for detection of lean vs. obese bacteria. For confirmation, a representative samples will be subjected to fluorescence in situ hybridization (FISH) followed by flow cytometry detection using 16S rRNA-targeted oligonucleotide probes. Consumer preference of the colored vs. traditional (white) potatoes will be measured using sensory analysis. Researchers will utilize the following methods/tools to disseminate the findings: presentations at grower association meetings, horticulture-field days, development of an educational web-site ( that may be linked to industry organizations and extension sites, additional workshops and publications in popular and scientific newsletters and/or journals.

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Nat'l. Inst. of Food and Agriculture
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Policy and Planning
Natural Toxins
Viruses and Prions
Bacterial Pathogens
Chemical Contaminants