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Evaluating the Effect of Selected Soaking Pretreatments on the Color Quality and Phenolic Content of Purple Potato Chips

Zhang, Kai
http://rave.ohiolink.edu/etdc/view?acc_num=osu1492612442758859

Abstract Details

2017, Master of Science, Ohio State University, Food Science and Technology.
Purple potato chips made from natural potato varieties with purple-bluish flesh are a novel alternative product to traditional potato chips. However, color loss and anthocyanin degradation occur during the processing of purple chips due to high frying temperature and Maillard browning. The objective of this study was to evaluate the influence of pretreatment soaking solutions on the color formation and phenolic content of purple potato chips. Purple potatoes (Purple majesty) were obtained from a local market in Columbus (OH, USA), and cut into slices of 2±0.2 mm. After washing in running water, slices were soaked in solutions of citric acid, acetic acid, sodium chloride (NaCl) or calcium chloride (CaCl2) using four different concentrations (0.1%, 0.2%, 1%, 2%) for 10 minutes, superficially dried and fried for 3 minutes in vegetable oil at 170 °C. Color (CIELab), monomeric anthocyanins, and total phenolics were monitored on the final product. Potato slices pretreated with 1% and 2% citric acid solutions had brighter purple-bluish color (L*=39.1±0.4, h*=317.9°±3.6°) with less browning compared to samples pretreated with other solutions (L*=22-33, h*=306 °-329 °). Potato chips pretreated with 1% and 2% citric acid solutions had higher monomeric anthocyanin content (50.3-63.7 mg Cyanidin- 3-glucoside equivalents /100g fries) and less polymeric anthocyanin color (25.4-35.7%) as compared to other samples (monomeric: 30.6-44.6 mg/100g Cyanidin-3- glucoside equivalents, polymeric: 51.4-69.4%). Soaking treatments had less impact on total phenolics. The phenolic content of potato chips with 1% and 2% citric acid ranged from 538.5-554.7 mg gallic acid equivalents (GAE)/100g chips, against 400.7-519.1 GAE mg/100g in other soaked samples. The major anthocyanin in raw purple potatoes was identified by HPLC as Petunidin-3-(p- coumaroyl)-rutinoside-5-glucoside which remained unchanged during the processing, along with Petunidin-3-(caffeoyl)-rutinoside-5-glucoside and Malvidin-3-(p-coumaroyl)- rutinoside-5-glucoside as minors. Potato chips were vacuum packed and stored at room temperature in the dark. Longer storage period resulted in the accumulation of polymerized anthocyanins in the purple potato chips. Changes in the phenolic content of chips remained constant around 520 mg gallic acid equivalents (GAE) /100g dry weight. Reducing sugar content in potato slices decreased from ~3.4 to 2.6 g/100g DW with water rinsing. Most soaking treatments helped decrease sugars levels even further, as low as ~1.0g/100g DW with citric acid. Citric and acetic acid soaking solutions had pH levels below 4, especially in 1% and 2% citric acid solutions (pH 2). This may have helped retain color and monomeric anthocyanin content, particularly on potato chips pretreated with 1% and 2% citric acid, since anthocyanins are inherently more stable under acidic conditions. Citric acid’s ability to function as an acidulant resulted in greater benefit as compared to other pretreatment chemicals tested. In conclusion, soaking colored potato slices in citric acid could be used as pretreatment to enhance the color and phenolic quality of fried purple potato chips with potential application on industrial scale.
Monica Giusti (Advisor)
Christopher Simons (Committee Member)
Lynn Knipe (Committee Member)
78 p.
Food Science
purple potato chips, Maillard browning, soaking, citric acid, reducing sugars, pH, color quality, monomeric anthocyanins, polymeric color, total phenolics

Recommended Citations

Citations

  • Zhang, K. (2017). Evaluating the Effect of Selected Soaking Pretreatments on the Color Quality and Phenolic Content of Purple Potato Chips [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492612442758859

    APA Style (7th edition)

  • Zhang, Kai. Evaluating the Effect of Selected Soaking Pretreatments on the Color Quality and Phenolic Content of Purple Potato Chips. 2017. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1492612442758859.

    MLA Style (8th edition)

  • Zhang, Kai. "Evaluating the Effect of Selected Soaking Pretreatments on the Color Quality and Phenolic Content of Purple Potato Chips." Master's thesis, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492612442758859

    Chicago Manual of Style (17th edition)

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This open access ETD is published by The Ohio State University and OhioLINK.