Purple-fleshed Potato Research Articles

Determination of Antioxidant Activity and Polyphenols Content in Chips by Raman and IR Spectroscopy

The application of vibrational spectroscopy for the determination of total polyphenols content, antioxidant activity, colour parameters, and fat level in chips originated from yellow-, red- and purple-fleshed potato varieties is reported. Raman, infrared (IR) and near-infrared (NIR) spectra of the laboratory-prepared chips were collected. Combining spectral data with the results of reference analyses, partial least squares regression models were built. To characterise and compare the elaborated models, the relative standard errors of prediction were calculated for calibration and validation sets. In the case of total phenolics quantification by Raman/IR/NIR techniques, these errors (%) amounted to 4.0/7.0/7.1 and 6.4/8.5/8.4 for calibration and validation samples, respectively, whereas they were 4.9/7.7/4.8 and 6.6/8.3/6.8 for antioxidant activity. The obtained results demonstrate that both infrared and Raman spectroscopy can effectively replace commonly used extraction methods. It follows that Raman spectroscopy has the highest potential to be adopted for the online potato-derived product analysis.

Changes in anthocyanidin levels during the maturation of color-fleshed potato (Solanum tuberosum L.) tubers

Certain potato cultivars are capable of producing anthocyanin pigments in the potato skin and flesh and those pigments have been shown, together with other phytochemicals, to promote good health. Six common anthocyanidins (cyanidin, delphinidin, petunidin, pelargonidin, malvidin and peonidin) were analyzed weekly for 15weeks in red- and purple-fleshed potato cultivars (Red Emma, Königspurpur, Valfi and Blaue de la Mancha) grown in field conditions using a validated LC-(+ESI)MS/MS method. Pelargonidin was the major type detected in red-fleshed cultivars whereas petunidin was the major type detected in the purple ones. Neither cyanidin nor delphinidin were found in any of the cultivars. The anthocyanidin levels observed were as high as 78mg/100g FW during tuber growth; however, fully matured tubers contained only 10–39mg anthocyanidins/100gFW. Anthocyanidin levels were moderately correlated with global solar irradiation (r<0.6252) but not with rainfall or daily temperature.

Modification of dietary fibers from purple-fleshed potatoes ( Heimeiren ) with high hydrostatic pressure and high pressure homogenization processing: A comparative study

Abstract In this study, we evaluated the effects of high hydrostatic pressure (HHP) and high pressure homogenization (HPH) treatments on the physicochemical, functional, and structural properties of dietary fibers (DFs) obtained from purple-fleshed potatoes. DFs subjected to HHP and HPH exhibited increased content of soluble dietary fiber. HHP and HPH treatments did not improve water holding capacity, but increased oil holding and swelling capacities, and emulsion activity and stability. DFs treated with HPH showed the increased antioxidant activities (DPPH 0.89, ABTS 2.65, FRAP 3.39 mg Trolox/g DF), content of total phenol, and α-glucosidase inhibition (98.3%). HHP and HPH treatments changed monosaccharide compositions and structural characteristics of DFs. Therefore, DFs from purple-fleshed potatoes could be used as a fiber-rich ingredient in functional foods, and HPH was more useful in the modification of dietary fiber than HHP at the same treatment conditions. Industrial relevance : This article deals with the modification of dietary fibers from purple-fleshed potatoes ( Heimeiren ) with HHP and HPH treatments. Results suggest that HPH treated dietary fiber showed a higher ratio of soluble fraction, increased physicochemical and functional properties than HHP at 200 MPa. There outcomes could help the food industry identify the optimal high pressure processing type to improve physicochemical and functional properties of dietary fiber.

A food-based approach that targets interleukin-6, a key regulator of chronic intestinal inflammation and colon carcinogenesis

Studies have shown a causal link between high-calorie diet (HCD) and colon cancer. However, molecular mechanisms are not fully elucidated. To understand etiology of HCD-induced colon carcinogenesis, we screened 10 pathways linked to elevated colonic cell proliferation and chronic inflammation in an HCD-consuming human-relevant pig model. We observed elevated colonic mucosal interleukin-6 (IL-6) expression in HCD-consuming pigs compared to standard diet controls (SD, P=.04), and IL-6 strongly correlated with Ki-67 proliferative index and zone, early biomarkers of colon cancer risk (r=0.604 and 0.743 and P=.017 and .002, respectively). Liquid chromatography–tandem mass spectrometry-based proteomic analysis and Ingenuity Pathway Analysis showed that HCD consumption altered IL-6 signaling pathway proteins (PI3KR4, IL-1α, Mapk10, Akt3, PIK3CG, PIK3R5, Map2k2). Furthermore, these proteins also correlated with Ki-67 proliferative index/zone. Anti-IL-6 therapeutics are available for treating colon cancer; however, they are expensive and induce negative side effects. Thus, whole foods could be a better way to combat low-grade chronic colonic inflammation and colon cancer. Whole plant foods have been shown to decrease chronic diseases due to the potential of anti-inflammatory dietary compounds acting synergistically. We observed that supplementation of HCD with anthocyanin-containing purple-fleshed potatoes (10% w/w), even after baking, suppressed HCD-induced IL-6 expression (P=.03) and the IL-6-related proteins IL-1α and Map2k1 (P≤.1). Our results highlight the importance of IL-6 signaling in diet-linked induction/prevention of colonic inflammation/cancer and demonstrate the potential of a food-based approach to target IL-6 signaling.

Cryopreservation and evaluations of vegetative growth, microtuber production and genetic stability in regenerants of purple-fleshed potato

Buds of in vitro-grown shoots of two purple-fleshed potato genotypes were successfully cryopreserved by encapsulation-vitrification (Encap-vitri) and droplet-vitrification (Drop-vitri). Optimal time durations of exposure to PVS2 for shoot regrowth of cryopreserved buds were 5–7 h and 6 h for ‘E03-2677’ and for ‘Blue Congo’, respectively, in Encap-vitri, and 30–50 min and 40 min for the former and the latter, respectively, in Drop-vitri. Higher rates of shoot regrowth were obtained in 1.5–2.0 mm-buds than in 1.0–1.4 mm-ones in Encap-vitri for ‘E03-2677’ and ‘Blue Congo’, while opposite results were found in Drop-vitri. In ‘Blue Congo’, only apical shoot tips survived and developed into shoots, with one shoot produced in one cryopreserved bud in Encap-vitri and Drop-vitri. In ‘E03-2677’, survival and shoot regrowth patterns were similar to those of ‘Blue Congo’ in Encap-vitri. However, both apical and axillary shoot tips survived and developed into two shoots in one bud in Drop-vitri. In ‘E03-2677’, histological observations revealed only apical shoot tips survived following Encap-vitri, while both apical and axillary shoot tips survived following Drop-vitri. Vegetative growth in shoots regenerated from Encap-vitri and Drop-vitri after 3 weeks of post-thaw culture was significantly lower than that from control, but markedly increased after 6 months of post-thaw culture. In both ‘E03-2677’ and ‘Blue Congo’, number of microtubers per shoot, per vessel and ≥3 mm in diameter were significantly greater in shoots regenerated from Encap-vitri than in those from the control. Assessments by ISSR and RAPD of genetic stability did not find any polymorphic bands in regenerants recovered from Encap-vitri and Drop-vitri. To the best of our knowledge, this is the first report on cryopreservation of purple-fleshed potato by vitrification-based procedures. Results reported here would provide valuable basic and technical information on cryopreservation of purple-fleshed potato.

Mathematical models of pretreatment processes to utilize purple-fleshed potato (Solanum tuberosum L.) peels for anthocyanin extraction

The effect of particle size on the extraction rate of anthocyanin from Solanum tuberosum L. (purple-fleshed potato) peels (PFPPs) using the stagnant single-stage batch extraction system was investigated. Core pretreatment processes such as drying and grinding were quantitatively evaluated using mathematical models. The drying behavior of PFPP was successfully described using thin layer models (Page model and Midilli-Kucuk model). The effective diffusion coefficient of drying temperature at 40°C was determined to be 1.67x10-12 m2/s. The grinding time to obtain particles of a specific size was accurately estimated using the grinding kinetic model (R 2=0.97). The extraction rate of anthocyanin increased as the particle size decreased; however, when the particle size was 0.15mm, the anthocyanin content decreased. Our study demonstrated that the grinding kinetic model is useful to estimate the grinding time to produce an optimum particle size for anthocyanin extraction from PFPP.

Extraction and purification of anthocyanins from purple-fleshed potato

Extraction and purification of anthocyanins from purple-fleshed potatoes was investigated. The effects of pretreatment method, time, and ethanol concentration on the extraction were studied. Boiling was the most efficient pretreatment method for the extraction. Extraction time and ethanol concentration were found to have only minor effect on the extraction yield. Six hour extraction time and 20vol.% ethanol concentration were found to be sufficient. The resulting anthocyanin-rich extract contained glucose, proteins, amino acids, and unidentified compounds as impurities. Removal of these by adsorption was studied with six commercially available adsorbents, of which Amberlite XAD-7HP was the most efficient. Anthocyanin purification with XAD-7HP was studied in a column. The effects of flow rate on adsorption, and ethanol and acetic acid concentrations on desorption were investigated. In loading, a highly dispersed anthocyanins breakthrough curve was obtained. This most likely resulted from agglomeration of anthocyanins. Desorption of anthocyanins could be done efficiently with 75vol.% acidic (7vol.% acetic acid) aqueous ethanol. All glucose and unknown impurities, together with 87% of proteins and amino acids, could be separated from the anthocyanins. Process scale-up was demonstrated by processing 19kg of purple-fleshed potatoes in a single batch.

Comparison of the postprandial effects of purple-fleshed and yellow-fleshed potatoes in healthy males with chemical characterization of the potato meals

The aim of the current study was to characterize the anthocyanin content and composition of a purple potato landrace cultivar (Solanum tuberosum ‘Synkeä Sakari’) and to compare the postprandial effects of purple-fleshed potatoes, yellow-fleshed potatoes and bilberries in potato starch on postprandial glycemia and insulinemia in healthy males. The purple potato meal caused smaller insulinemia than the yellow potato meal (iAUC 120 min 1347 and 2226, respectively, p = 0.012 and iAUC 240 min 1448 and 2403, p = 0.007) or the bilberry meal (iAUC 120 min 1920, p = 0.027). The purple potato meal caused a smaller plasma glucose at 40 min postprandially compared with the yellow potato meal (p = 0.044). The results of this study suggest that anthocyanin-containing purple-fleshed potatoes influence the postprandial insulinemia positively. Since potatoes are the world’s largest non-grain commodity, replacing yellow-fleshed potatoes with purple-fleshed potatoes as staple food could have large potential in maintaining public health.

α-Solanine Isolated From Solanum Tuberosum L. cv Jayoung Abrogates LPS-Induced Inflammatory Responses Via NF-κB Inactivation in RAW 264.7 Macrophages and Endotoxin-Induced Shock Model in Mice.

α-Solanine, a trisaccharide glycoalkaloid, has been reported to possess anti-cancer effects. In this study, we investigated the anti-inflammatory effects of α-solanine isolated from "Jayoung" a dark purple-fleshed potato by examining its in vitro inhibitory effects on inducible nitric-oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and pro-inflammatory cytokines in LPS-induced RAW 264.7 macrophages and its in vivo effects on LPS-induced septic shock in a mouse model. α-Solanine suppressed the expression of iNOS and COX-2 both at protein and mRNA levels and consequently inhibited nitric oxide (NO) and prostaglandin E2 (PGE2 ) production in LPS-induced RAW 264.7 macrophages. α-Solanine also reduced the production and mRNA expression of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) induced by LPS. Furthermore, molecular mechanism studies indicated that α-solanine inhibited LPS-induced activation of nuclear factor-κB (NF-κB) by reducing nuclear translocation of p65, degradation of inhibitory κBα (IκBα), and phosphorylation of IκB kinaseα/β (IKKα/β). In an in vivo experiment of LPS-induced endotoxemia, treatment with α-solanine suppressed mRNA expressions of iNOS, COX-2, IL-6, TNF-α, and IL-1β, and the activation of NF-κB in liver. Importantly, α-solanine increased the survival rate of mice in LPS-induced endotoxemia and polymicrobial sepsis models. Taken together, our data suggest that the α-solanine may be a promising therapeutic against inflammatory diseases by inhibiting the NF-κB signaling pathway. J. Cell. Biochem. 117: 2327-2339, 2016. © 2016 Wiley Periodicals, Inc.

Can Your Microbiome Tell You What to Eat?

Prospects for using the gut microbiome for personalized medicine are substantial since the gut microbiome is known to modulate metabolism and varies substantially among individuals. Zeevi etal. (2015) demonstrate that the gut microbiota can be used to predict individualized blood glucose responses to particular foods, which differ between individuals.

Domestic cooking methods affect the phytochemical composition and antioxidant activity of purple-fleshed potatoes

The effects of domestic cooking methods (boiling, baking, steaming, microwaving, frying, and stir-frying) and a new cooking method (air-frying) on the composition of phytochemicals (phenolics, anthocyanins, and carotenoids) and the antioxidant activity in purple-fleshed potatoes were investigated. Compared with raw potatoes, reductions of 23.59–90.42%, 7.09–72.44%, 7.45–83.15%, and 20.15–76.16% in the vitamin C, total phenolic, anthocyanin and carotenoid contents, respectively, was observed after cooking. Decreases of 7.88%, 21.55%, 22.48, 6.31%, and 61.38% in DPPH radical-scavenging activity was also observed after boiling, steaming, baking, microwaving and stir-frying, respectively, whereas an increase of 30.52% was noted after air-frying. A correlation analysis revealed that the antioxidant activity was in accordance with the total phenolic content and that this activity showed the lowest correlation with the vitamin C content. Among all of the cooking methods investigated in this study, stir-frying retained only slight levels of the phytochemicals and antioxidant activity observed in raw potatoes, whereas steaming and microwaving were able to retain most of the health-promoting compounds found in raw potatoes and may thus be suitable methods for cooking potatoes.

Anthocyanin-containing purple-fleshed potatoes suppress colon tumorigenesis via elimination of colon cancer stem cells

Cancer stem cells (CSCs) are shown to be responsible for initiation and progression of tumors in a variety of cancers. We previously showed that anthocyanin-containing baked purple-fleshed potato (PP) extracts (PA) suppressed early and advanced human colon cancer cell proliferation and induced apoptosis, but their effect on colon CSCs is not known. Considering the evidence of bioactive compounds, such as anthocyanins, against cancers, there is a critical need to study anticancer activity of PP, a global food crop, against colon CSCs. Thus, isolated colon CSCs (positive for CD44, CD133 and ALDH1b1 markers) with functioning p53 and shRNA-attenuated p53 were treated with PA at 5.0 μg/ml. Effects of baked PP (20% wt/wt) against colon CSCs were also tested in vivo in mice with azoxymethane-induced colon tumorigenesis. Effects of PA/PP were compared to positive control sulindac. In vitro, PA suppressed proliferation and elevated apoptosis in a p53-independent manner in colon CSCs. PA, but not sulindac, suppressed levels of Wnt pathway effector β-catenin (a critical regulator of CSC proliferation) and its downstream proteins (c-Myc and cyclin D1) and elevated Bax and cytochrome c, proteins-mediating mitochondrial apoptosis. In vivo, PP reduced the number of crypts containing cells with nuclear β-catenin (an indicator of colon CSCs) via induction of apoptosis and suppressed tumor incidence similar to that of sulindac. Combined, our data suggest that PP may contribute to reduced colon CSCs number and tumor incidence in vivo via suppression of Wnt/β-catenin signaling and elevation of mitochondria-mediated apoptosis.

Physico-Chemical and Structural Characteristics of Vegetables Cooked Under Sous-Vide, Cook-Vide, and Conventional Boiling.

In this paper, physico-chemical and structural properties of cut and cooked purple-flesh potato, green bean pods, and carrots have been studied. Three different cooking methods have been applied: traditional cooking (boiling water at 100 °C), cook-vide (at 80 and 90 °C) and sous-vide (at 80 °C and 90 °C). Similar firmness was obtained in potato applying the same cooking time using traditional cooking (100 °C), and cook-vide and sous-vide at 90 °C, while in green beans and carrots the application of the sous-vide (90 °C) required longer cooking times than cook-vide (90 °C) and traditional cooking (100 °C). Losses in anthocyanins (for purple-flesh potatoes) and ascorbic acid (for green beans) were higher applying traditional cooking. β-Carotene extraction increased in carrots with traditional cooking and cook-vide (P < 0.05). Cryo-SEM micrographs suggested higher swelling pressure of starch in potatoes cells cooked in contact with water, such as traditional cooking and cook-vide. Traditional cooking was the most aggressive treatment in green beans because the secondary walls were reduced compared with sous-vide and cook-vide. Sous-vide preserved organelles in the carrot cells, which could explain the lower extraction of β-carotene compared with cook-vide and traditional cooking. Sous-vide cooking of purple-flesh potato is recommended to maintain its high anthocyanin content. Traditional boiling could be recommended for carrots because increase β-carotenes availability. For green beans, cook-vide, and sous-vide provided products with higher ascorbic acid content.

Antioxidant activity and quality of red and purple flesh potato chips

Polyphenolic compounds with anthocyanins characteristic for coloured flesh potatoes are known for their antioxidant properties which could improve the quality of ready products as potato chips. Five purple potato varieties (Blaue Elise, Blaue St. Galler, Blue Congo, Valfi and Vitelotte) and four red flesh potato varieties (Highland Burgundy Red, Herbie 26, Rosalinde, Rote Emma) were stored for nine months and analysed for the polyphenols, anthocyanins, reducing sugars and antioxidant activity with two different methods viz. ABTS and DPPH. After additionally in prepared potato chips oil content, texture and colour parameters were evaluated.Both, red and purple fleshed potato varieties contained higher content of total polyphenols (250–526 mg 100 g−1 DW) and anthocyanins (16–57 mg 100 g−1 DW). The higher content of polyphenols are directly related to higher antioxidant activity of tested potatoes. The process of frying caused almost total degradation of anthocyanin compounds, while polyphenols exhibited quite good stability (especially in chips obtained from red fleshed potatoes). The antioxidant activity decreased significantly in chips obtained from purple fleshed potatoes. Better stability after long term storage exhibited red fleshed varieties and also obtained chips exhibited better properties.

Purple‐fleshed potato, even after processing, prevents and reverses high‐fat diet elevated colonic‐mesenteric fatősystemic inflammation cascade in pig model (1045.47)

High‐fat diet (HFD) elevated colonic/adipose tissue inflammation strongly correlates with lipopolysaccharide (LPS) induced TLR‐4 activation. We have previously shown that purple‐fleshed potatoes (PP) suppress colonic/systemic oxidative stress markers in HFD consuming pigs. We hypothesized that PP, even after processing; suppress HFD induced colonic/mesenteric fat inflammation via suppression of LPS/TLR‐4 signalling compared to white‐fleshed potatoes (WP). We performed 2 studies ‐ a prevention study where 64 pigs consumed one of the 8 diets: Standard diet (SD), HFD and HFD supplemented with raw/baked/chips PP or WP (10% w/w) for 13 wk; and a reversal study where pigs (12 wk on HFD) consumed HFD containing 10/20% PP or WP chips for 5 wk (n=8). In the prevention study, all potato diets suppressed (P &lt; 0.05) HFD elevated colonic/mesenteric fat expression of TLR‐4 and downstream NF‐κB and TNF‐α (qPCR), and serum IL‐1β (Immunoassay). In the reversal study, colonic/mesenteric fat expression of TLR‐4, NF‐κB and TNF‐α were consistently suppressed only in PP group (not WP) compared to HFD control (P &lt; 0.05), suggesting that time of intervention is important. In addition, PP extracts suppressed LPS or TNF‐α induced NF‐κB activation in Caco‐2 cells compared to WP. Collectively, these results suggest that PP were more potent in reversing the HFD elevated colonic‐mesenteric fat‐systemic inflammatory cascade.Grant Funding Source: Supported by USDA‐NIFA NRI Grant 2009‐55200‐05197

The effect of frying on anthocyanin stability and antioxidant activity of crisps from red- and purple-fleshed potatoes (Solanum tuberosum L.)

Red- and purple-fleshed potatoes (Solanum tuberosum L.) are a good source of polyphenols, mainly anthocyanins as one of the most important components. The chemical composition with reducing sugars and the total polyphenol contents were analyzed in four purple potato varieties (Salad Blue, Vitelotte, Valfi, Blue Congo) and three red-fleshed potato varieties (Rosalinde, Herbie 26, Highland Burgundy Red). The anthocyanin composition of raw potato and potato crisps was characterized by high-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) method. Moreover, the antioxidant activity was measured with the radical scavenging assays using 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical as well as ferric reducing ability of plasma assay (FRAP). In addition, colour parameters in prepared potato crisps were evaluated. Both red and purple-fleshed potato varieties contained high levels of total polyphenols (227–845mg 100g−1dryweight) and anthocyanins (21–109mg100g−1dryweight). The process of frying caused degradation of anthocyanin compounds (38–70%). The HPLC–MS/MS analysis showed that pelargonidin and malvidin derivates were more stable during frying than petunidin derivatives. Although frying process affected the anthocyanin and polyphenol levels, obtained potato crisps exhibited bright intensive colour and good antioxidant activity.

Anti-diabetic and hypolipidemic effects of purple-fleshed potato in streptozotocin-induced diabetic rats

The purpose of this study was to investigate the effects of purple-fleshed potatoes on blood glucose level (BGL), insulin and lipid levels in streptozotocin (STZ) induced diabetic rats for 7 weeks. Test groups were divided into non-diabetic control and diabetic groups. The diabetic groups were further divided into three groups: diabetes mellitus (DM) control, 10% purple-fleshed potato DM (10PP-DM), and 20% purple-fleshed potato DM (20PPDM) groups. Three weeks after initiating the experimental diet, BGL was significantly lower in the 10PP-DM and 20PP-DM groups compared to the DM control group. As for serum insulin levels, the 20PP-DM group was significantly higher than in the DM control group. While serum cholesterol level was significantly lower in the 20PP-DM group, serum triglyceride level was significantly lower in the 10PP-DM group than in the DM control group. We concluded that a 20PP powder intake improves both diabetes and lipid control in diabetic rats by significantly improving serum insulin level and lowering BGL and serum cholesterol level.

Processed purple‐fleshed potato prevents and protects against high‐fat diet elevated oxidative stress and inflammation markers in vivo in a pig model

Little information exists if purple‐fleshed potatoes (PP), rich in anti‐oxidant and anti‐inflammatory anthocyanins, even after processing, retain their health benefiting properties in vivo. We hypothesized that processed PP will suppress high‐fat diet (HFD) elevated oxidative stress/inflammation biomarkers in a pig model. Thus, we performed two studies; a prevention study where 64 pigs, 3wk post‐weaning, consumed one of the eight diets; low‐fat (LFD), HFD and HFD supplemented with white‐fleshed potato (WP) or PP (raw/baked/chips; 10% w/w) for 13wk; and a protection study where pigs (12 wk on HFD) consumed HFD containing 10/20% PP or WP chips for additional 5wk (n=8). Both PP and WP diets (raw/baked/chips) suppressed urinary oxidative stress markers, 8‐isoprostane (8IP) and DNA adduct 8‐OHDG; and serum levels of TNF‐α (ELISA) compared to HFD control (P=0.038). Potato diets elevated colonic mucosal glutathione ratio (GSH:GSSG) compared to HFD control, however, greatest enhancement (P=0.046) was seen in raw PP consuming pigs. In the protection study, biomarkers of oxidative stress and inflammation, including colonic mucosal expression of COX‐2 and IFN‐γ (qRTPCR), and systemic levels of 8IP and TNF‐α were suppressed (P=0.049) by PP diets compared to control. These findings indicate that PP, even after processing, prevents and protects against HFD elevated colonic‐systemic oxidative stress/inflammation.Grant Funding Source: This work was supported by National Research Initiative Grant 2009–55200‐05197 from the USDA‐NIFA.

Purple‐fleshed potatoes suppress colon‐systemic oxidative stress/inflammatory markers via alternations in the gut bacterial signature

Purple‐fleshed potatoes (PP) are rich in putative anti‐oxidant/antiinflammatory anthocyanins. We hypothesized that PP, even after processing, suppress colon‐systemic oxidative stress/inflammatory markers by altering gut bacterial signature and metabolite profile. To test this hypothesis, 40 pigs on high‐fat diet (HFD) for 12 wk were provided with one of the five diets: HFD, white‐fleshed potato (WP) or PP chips at 10/20% for 5 wk. Serum, distal colon mucosa/digesta and fecal samples were utilized to analyze oxidative stress (MDA; colorimetric assay) and inflammatory (TNFα; ELISA and prostaglandins; LC‐MS/MS) markers, gut bacteria (pyrosequencing) and metabolites (LC‐MS). All diets, except WP (20%), suppressed (p = 0.04) systemic levels of TNFα compared to HFD. However, only PP suppressed MDA and colonic PGE2 levels (p ≤ 0.05). Potato diets increased members of Clostridia and Lachnospiraceae. Only PP increased distal colon bacteroidetes to firmicutes ratio (BFR) compared to HFD. This is particularly important as BFR is reduced during obesity. Indeed, MDA and TNFα elevated during obesity positively correlated with Firmicutes (0.518, p = 0.002; 0.380, p = 0.024, respectively) and MDA negatively correlated with BFR (−0.413, p = 0.036). Preliminary metabolomics data revealed 4350 metabolites in both distal colon and feces and the correlations with gut bacteria are being carried out.Grant Funding Source: National Research Initiative Grant 2009–55200‐05197 from the USDA National Institute for Food and Agriculture (2009–2012)

Total phenolic, total anthocyanin and phenolic acid concentrations and antioxidant activity of purple-fleshed potatoes as affected by boiling

The effect of boiling on concentrations of total phenolics (TP), total anthocyanins (TA) and phenolic acids (PA) and on antioxidant activity (AA) of purple-fleshed potatoes belonging to (Solanum andigenum) was determined in four native Andean accessions. Extraction methods for each parameter were optimized for raw and boiled freeze dried samples. The concentration of methanol strongly influenced the extraction of TP and antioxidants to be evaluated for AA, with 80% and 60% methanol, being more efficient for raw and for boiled potato samples, respectively. The predominant PA in raw and boiled potato tubers was chlorogenic acid (CA). Caffeic acid was also present in raw tubers but drastically decrease in boiled tubers. For all accessions, the concentrations of TP and AA determined in boiled tubers were higher than in raw tubers. However, with the exception of Guincho, the TA and CA concentrations determined in raw and boiled tubers of the accessions were not significantly different. The deep purple-fleshed accession Guincho showed the highest TA concentration (418mg/100g, FW) and AA (17,305μg Trolox equivalent/g, FW). Boiled purple-fleshed potatoes are a good source of TA and show high AA, and can probably contributes significantly to the intake of health-promoting phenolic compounds.