Pigmented potato cultivars were ranked by a consumer panel for overall acceptance, and acceptance of aroma, appearance, and flavor. Potatoes were analyzed for total phenolics, anthocyanins and carotenoids. Concentrations of total phenolics in yellow and purple potato cultivars were 2-fold greater (P < 0.001) than in the white cultivar. Anthocyanins were low to non-detectable in white and yellow potatoes. Purple potatoes anthocyanin concentration was 20-fold greater (P < 0.001) than in yellow potatoes. Carotenoid concentrations in white and purple potatoes were similar, while yellow potatoes had a 45-fold greater carotenoids concentration compared to white and purple potatoes. Consumers ranked the aroma and appearance of white and yellow potatoes higher than purple (P < 0.05). However, no significant differences were observed in overall acceptance between the potato cultivars. These results suggest that consumers may be willing to consume pigmented potatoes, which are beneficial to health due to their higher antioxidant content.
High intake of fruits and vegetables rich in antioxidants has been linked to a decreased risk in the development of chronic diseases [
Phenolic acids, anthocyanins and carotenoids are reported to have multiple beneficial properties, including anti-inflammatory [6-8], anti-carcinogenic [9-11] and cardio-protective [12-14] effects. Consumption of pigmented potatoes rich in these antioxidants may reduce the risk of chronic diseases.
The increased awareness of the health benefits of antioxidants found in fruits and vegetables has promoted the development of breeding programs designed to enhance flavor, diversify color and increase antioxidant concentrations in potatoes [
We recently reported [
White- (Russet Burbank), yellow- (PORO3PG6-3), and purple-flesh (PORO4PG82-1) potato (Solanum tuberosum L.) cultivars grown in Toppenish, Washington were used in the study.
Whole potatoes (8 kg) were randomly selected, washed, abrasively peeled (1.5 min), cut into 6 mm thick slices, and steam blanched for 8 min at 133˚C. The potatoes were rapidly cooled in an ice-water bath for 8 min and mixed to a uniform consistency in a Hobart mixer (The Hobart Mfg. Co., Troy, OH). The potato slurries were immediately frozen at –35˚C until assay. Potato slurries were analyzed in triplicate for total antioxidant activity, phenolic acid, anthocyanin and carotenoid content.
Total phenolic acids were quantified as previously described [
Total anthocyanin content was determined by the pH differential method as previously described, with modifications [23,24]. Briefly, 2.45 g potato slurry was homogenized in 20 mL of a 95% ethanol and 1.5 N HCl mixture (85:15, v/v), incubated for 90 min at 4˚C, and centrifuged at 14,000 × g for 15 min at 4˚C. Five mL of the supernatant was added to 45 mL of 0.025 M potassium chloride buffer (pH 1.0) or 0.4 M sodium acetate buffer (pH 4.5) and equilibrated for 15 min. Absorbance was read at 535 and 700 nm and total anthocyanin concentration expressed as malvidin-3-p-coumarylglycoside equivalents.
Carotenoids were extracted by adding 15 mL acetone to 3 g of potato slurry, vortexing 30 min on a multi-tube vortexer (Scientific Manufacturing Industry model 2601, Emeryville, CA), and centrifuging at 1000 × g for 15 min at 4˚C. This extraction was repeated twice. The acetone was pooled and dried under nitrogen gas at 40˚C. White and purple potato dried residues were dissolved in 1 mL acetone and yellow potatoes in 3 mL acetone. Absorbance was read at 444 nm. Total carotenoids were calculated using the extinction coefficient for lutein, and expressed as µg total carotenoid/g dry matter [
Freshly harvested potatoes were stored at 4˚C, 95% RH until required for evaluations. On the day of the sensory study, potatoes were allowed to equilibrate to room temperature for 24 h. Potatoes were wrapped in aluminum foil and baked at 204˚C in a conventional oven for 105 min as previously described [
For each attribute, potato cultivars were ranked by 60 untrained panelists (29 males and 31 females, ages 18 - 62). The Institutional Review Board of Washington State University approved all study procedures. Panelists were asked to rank cultivars in order of acceptance with 1 = most accepted and 3 = least accepted for aroma, appearance, flavor, and overall quality. Unsalted crackers and reagent grade water were provided for cleansing the palate between samples.
Panelist ranking of potato cultivar aroma, appearance, flavor and overall quality were reported as rank sum using Compusense sensory software (version 4.6; Compusense Inc., Ontario, Canada). The most preferred samples were represented by the lowest value (sum of panelist responses). Statistical significance was analyzed by Friedman’s analysis of ranked sums and means separation was determined by Tukey’s HSD. Total phenolics, anthocyanins and carotenoids among cultivars were compared by ANOVA using the General Linear Models procedure of SAS (version 8; SAS Institute, Cary, NC). Differences in treatment means were compared using protected LSD. Statistical significance was established at P < 0.05.
The purpose of this study was to determine the acceptability of white-, yellowand purple-flesh potatoes by consumers, compare the sensory evaluations of the pigmented potatoes to the commonly consumed white potato, and relate antioxidant concentrations to consumer acceptability. To our knowledge, this is the first study on sensory preferences for different pigmented potato cultivars and relating the antioxidant profiles to the sensory preferences. The antioxidant concentrations of the potato cultivars are shown in
Yellow and purple cultivars had the highest concentration of total phenolics (3.2 and 3.1 mg/g, respectively), and concentrations were 2-fold greater (P < 0.001) than in the white cultivar (1.5 mg/g). Anthocyanins were not detectable in the white cultivar, and low in the yellow cultivar. The purple potatoes had a 20-fold greater (P < 0.001) concentration of anthocyanins than the yellow. White and purple cultivars had the same concentration of carotenoids (1.3 μg/g), while yellow potatoes had a 45-fold greater (58.1 μg/g; P < 0.001) concentration of carotenoids compared to both white and purple potatoes.
Sensory rank sum values for sensory attributes of the different potato cultivars are shown in
Based on appearance and aroma, the purple potato was ranked as the least accepted (P < 0.001) potato compared
1g/kg; 2mg/kg; a,bDifferent letters denote significant difference (P < 0.001).
1The more accepted cultivar is represented by the lower value. a,bDifferent letters denote significant difference (P < 0.05).
to other potatoes. The purple-flesh potatoes had high (P < 0.001) concentrations of anthocyanins compared to white and yellow cultivars, which are responsible for purple skin and flesh color. The color of food plays a major role in perception of aroma, flavor and texture: color tends to give the perception of stronger odor intensity in foods when compared to non-colored counterparts [
White potatoes were ranked as the most favorable in appearance. These results may be explained by the familiarity of consumers with white potatoes. Consumers would likely be more familiar with white potatoes compared to pigmented potatoes, thus the rankings of the white potato for aroma and appearance acceptance were more favorable. The pigmented potatoes (yellow and purple) were higher (P < 0.001) in total phenolics compared to the yellow potatoes. Yellow potatoes were higher (P < 0.001) in total carotenoids and purple potatoes were higher (P < 0.001) in total anthocyanins, compared to white potatoes. White Russet-like potatoes are the most commonly consumed potatoes in the US [
Panelist ranked the appearance of yellow potatoes between white and purple potatoes, with white and yellow potatoes not being significantly different. Comments from panelists suggested that the yellow color potato flesh was positively associated with sweet potatoes, and therefore many panelists found yellow potatoes more acceptable. Sensory research involving carrots has demonstrated that consumers consistently preferred orange and white carrots over purple carrots, when evaluated for sensory attributes similar to those used in this study [
Compared to purple-flesh potatoes, yellow-flesh was ranked as more acceptable for aroma and appearance but not significantly different from white potatoes. Yellow potatoes have the highest amount of carotenoids (P < 0.001) compared to the other cultivars, and this may have influenced aroma and flavor. Carotenoids are known to produce aromas via enzymatic and non-enzymatic pathways; volatile compounds have been found in carotenoid-containing fruits, vegetables, and white wines [
This study showed that in terms of antioxidant concentration, including total phenolics, anthocyanins and carotenoids, large differences were observed between white, yellow and purple potatoes. When these potatoes were ranked for the acceptance of sensory attributes by a consumer panel, results showed that purple potatoes were ranked as least accepted for appearance and aroma compared to yellow and white potatoes. Since color is known to have an effect on sensory perception of different foods, this may have played a role in the favorable flavor perception of yellow and purple potatoes. However, no significant differences were observed between the three potatoes for flavor and overall acceptance. These results indicated that pigmented potatoes are acceptable to consumers. Therefore, consumption of pigmented potatoes can potentially provide additional health benefits due to the higher content of phenolic acids, anthocyanins and carotenoids.
Funding for this project was received from the Washington State Potato Commission and the US Potato Board.