Purple-fleshed Potato Research Articles

Studying the Stability of Anthocyanin Pigments Isolated from Juices of Colored-Fleshed Potatoes

The aim of this study was to obtain extracts of anthocyanin pigments from red and purple-fleshed potato juices characterized by stable color. For this purpose, potato juices were pasteurized at different temperatures or fruit and vegetable concentrates were added to them. Color stability tests of the obtained pigments were carried out in model pH and temperature conditions and after adding to natural yogurt. Both the pasteurization process and the addition of fruit and vegetable concentrates to the potato juices positively affected their color and its stability in time. However, the pasteurization of the potato juices had a negative effect on the content of biologically active compounds, in contrast to the juices stabilized with the addition of fruit and vegetable concentrates. Anthocyanin pigments from red-fleshed potato juices were more stable than those isolated from the purple-fleshed potato juices. The results of model tests of the anthocyanin pigment concentrates from the colored-flesh potatoes and natural yoghurts with their addition confirmed the high stability of the tested concentrates.

Integrated transcriptomic and metabolomic analyses reveal transcriptional regulatory network for phenolic acid biosynthesis in potato tubers

The phenolic acid profile and concentration in potatoes signify their nutritional significance and functional value. In this study, a total of 398 metabolites, including 52 phenolic acids, were identified from three colored potato clones at three developmental stages using widely targeted metabolomics. Red and purple-fleshed potatoes exhibit higher levels of most phenolic acids compared to yellow-fleshed potatoes, particularly notable in their chlorogenic acid content. We concentrated on the distribution of differentially expressed transcription factors (TFs) among these clones, pinpointing the ERF (ethylene response factor), bHLH (basic helix-loop-helix), and MYB (myeloblastosis) as the predominant TFs via RNA-Seq analysis. Based on integrated transcriptomic and widely targeted metabolomic analysis, 23 pathway genes that might be involved in the biosynthesis of phenolic acid were identified. Furthermore, three central modules and several hub genes, encompassing 7 TFs, were identified. Notably, bHLH1 was identified as a key transcriptional regulator within this network, specifically activating the transcription of StCCoAOMT, a key enzyme catalyzing the methylation of caffeoyl-CoA to feruloyl-CoA. This study may provide new insights into the molecular mechanisms of phenolic acid biosynthesis in potatoes and potentially advances the development of functional food products derived from these potatoes.

Pulsed Electric Fields (PEF) Treatment Prior to Hot-Air and Microwave Drying of Yellow- and Purple-Fleshed Potatoes

AbstractThis study investigated the impact of pulsed electric fields (PEF) treatment combined with hot-air (HA) and microwave (MW) drying on the quality attributes of yellow and purple potato samples. PEF + HA and PEF + MW treatments showed no significant difference in total phenolic content for yellow potatoes. However, the raw purple sample exhibited significantly higher phenolic content compared to purple PEF1 and PEF3 samples. DPPH antioxidant activity for yellow and purple potatoes ranged from 18.48 to 33.19% with HA drying, and from 21.38 to 39.94% with MW drying. MW drying following PEF treatment was more effective in enhancing antioxidant activity compared to HA drying. However, it was observed that PEF levels had no statistical effect on total monomeric anthocyanin. PEF treatment prior to drying may be recommended in practice as it does not cause structural changes in SEM analysis. According to FTIR results, PEF and drying processes caused some changes in the chemical structure of potato samples. In the PCA results, the untreated purple HA sample exhibited characteristics that were most similar to those of the raw purple potato sample. Conversely, the yellow PEF + MW and untreated yellow with MW samples displayed properties closest to the raw yellow potato samples. According to chemometric analysis, the models exhibit high rCV and rPre values coupled with low RMSEC and RMSEP values and negligible disparities between them, indicating strong correlations between the predicted and reference values.

Optimization of Process Parameters for Microwave Drying of Yellow- and Purple-Fleshed Potatoes

The main objective of the present work was to study the optimization of microwave drying of potatoes that have different flesh colors. The effects of independent variables of microwave power (300, 450, 600 W), slice thickness (2–4, 6 mm), and steam blanching time (2, 5, 8 min) on the color, total phenolic content (TPC), antioxidant activity, starch ratio, and total monomeric anthocyanin content (TMA) were investigated by using the Response Surface Methodology (RSM). Before drying, potato slices that had different thicknesses were blanched in steam at 90 °C for indicated times. Optimization was applied to improve bioactive compounds, starch ratio, and color. The optimum drying parameters were determined as 300 W, 6 mm, and 8 min for purple-fleshed potatoes, and 450 W, 6 mm, and 2 min for yellow-fleshed potatoes. This study is beneficial to the development of the processing of potatoes in the food industry and provides more insights into the application of microwave drying technology.

Mor etli patatesin sıcak hava koşullarının optimizasyonu

One of the most popular techniques for preserving fruits and vegetables is drying. Many drying methods have advantages and disadvantages. The purpose of this study was to optimize the hot air drying conditions of a novel variety of purple-fleshed potato with response surface method (RSM) by considering the duration of the steaming process applied before drying, slice thickness, and drying temperature. The optimum drying conditions were determined by analyses such as total phenolic compound, antioxidant activity, chroma, and starch ratio in purple-fleshed potato powders obtained as a result of drying by considering different drying temperatures (55, 65, 75 °C), steam blanching times (2, 5, 8 min) and slice thickness (2, 4, 6 mm). Following optimization, it was discovered that the drying temperature, slice thickness, and steam blanching time were, respectively, 55 °C, 5.80 mm, and 4 minutes. Consequently, the generated product experiences reduced discoloration, quality loss, and reduction of bioactive components.

Impacts of Pulsed Electric Fields (PEF) Pre-treatment on the Characteristics of Fried Yellow- and Purple-Fleshed Potatoes: a Chemometric-Assisted FTIR Study

Impacts of Pulsed Electric Fields (PEF) Pre-treatment on the Characteristics of Fried Yellow- and Purple-Fleshed Potatoes: a Chemometric-Assisted FTIR Study

Application of vibrational and fluorescence spectroscopy to the compositional analysis of colored-flesh potatoes.

Determination of composition and physicochemical parameters of natural products requires dedicated, often laborious and expensive, analytical protocols. Different spectroscopic techniques, in conjunction with chemometrics, seem to have a considerable potential in direct analysis of raw plant material and foods, without any chemical treatment. Fluorescence spectroscopy and three vibrational spectroscopy techniques were applied to determine total polyphenol content, antioxidant activity and macronutrient levels in red- and purple-fleshed potato varieties. Excitation-emission matrix fluorescence, Fourier transform Raman, attenuated total reflection Fourier transform infrared and near-infrared spectra were recorded for the freeze-dried samples. Combining spectral data and the results of reference analyses, partial least squares regression models were constructed for each parameter studied. For polyphenols and antioxidant activity, quantification errors found for validation samples amounted to 3.74-5.04% and 4.75-6.35%, respectively, whereas macronutrient analysis gave errors in the 3.45-4.55%, 3.09-5.30% and 5.10-8.58% ranges for starch, protein and sugar determinations, respectively. The obtained results demonstrate that different spectroscopic techniques in combination with multivariate modeling allow simultaneous determination of various parameters of plant samples based on a single sample spectrum. They can effectively replace commonly used protocols of food product analysis requiring sample dissolving and extraction of the compounds of interest. © 2023 Society of Chemical Industry.

Targeted Primary and Secondary Metabolite Analysis of Colored Potato “Michuñe Negra” Grown in Soilless Culture and during Prolonged Cold Storage: Implications in Acrylamide Formation during Frying

Colored potatoes have been of interest because of their nutritional and health-promoting properties. However, their aptitude for processing regarding acrylamide formation levels is highly variable and for the most part unknown. In this work, the effect of cultivation season (summer and winter), and postharvest cold storage (1, 2, and 5 months at 5 °C ± 1 °C) on the Maillard reaction precursors (reducing sugars, sucrose, and asparagine), phenolic compounds (anthocyanins, phenolic acids and other flavonoids), and acrylamide after frying (GC-MS) were assessed on the “Michuñe negra” potato cultivar from the southern region of Chile grown under fertigation. Acrylamide levels were surveyed on six samples of commercial colored potato chips for comparison purposes. Cultivation season and cold storage showed an effect on both main primary and secondary metabolites. The amount of reducing sugars such as fructose increased with cold storage. Anthocyanin and phenolic contents were higher in the winter season and increased with cold storage. Acrylamide levels were high, surpassing the EFSA benchmark value (750 µg kg−1) in all cases, notably in chips made after one month of cold storage (2125% higher). Additional measures in both agronomical and processing stages of the purple-fleshed potato need to be implemented to lower the acrylamide levels down to acceptable values.

In Vitro Cultivation of Purple-Fleshed Potato Varieties: Insights into Their Growth and Development

Purple-fleshed potatoes (PFP) are varieties of Solanum tuberosum L., which recently have been recorded to be more and more cultivated and consumed in all European countries, including Romania, as they are promoted for their content in bioactive compounds and benefits to human health. This paper presents a micropropagation protocol study for PFP varieties already traded into the Romanian market, namely Blue Danube (BD), Salad Blue (SB), Violet Negretin (VN), and Violet Queen (VQ). These varieties were tested for in vitro micropropagation also considering asepsis, initiation, callus formation, and microtuberization. To establish the optimum asepsis treatment, a preliminary experiment was performed and, the best results were obtained by using 70% EtOH (1 min) followed by 20% (v/v) Domestos® (20 min). The MS formula (Murashige and Skoog 1962) was tested as the basic culture medium without growth regulators for all tested stages except for callus initiation and its further multiplication stages. The effect of glycine on direct organogenesis and shoot multiplication was evaluated for propagated micro-cuttings. We emphasize that the addition of glycine at a concentration of 15 mg/L to the culture medium induced a better plantlet vigor for all four varieties. Regarding the indirect organogenesis, culture medium supplemented with NAA (5.00 mg/L), GA3 (1.00 mg/L), TDZ (1.00 mg/L) and glycine (15.00 mg/L) induced the best results for shoot cluster regeneration as well as turning of white callus from control to purple callus. Further, the microtuberization was successfully produced when sucrose was supplemented at 8% (w/v) into the culture medium. Among all four tested PFP varieties, SB has proven to give the best results regarding the adaptability for in vitro cultivation.

Arbuscular Mycorrhizal Fungi Increase the Yield and Nutritional Quality of Yellow and Purple Fleshed Potatoes (Solanum tuberosum)

Arbuscular Mycorrhizal Fungi Increase the Yield and Nutritional Quality of Yellow and Purple Fleshed Potatoes (Solanum tuberosum)

Physical Pretreatments to Enhance Purple-Fleshed Potatoes Drying: Effects of Blanching, Ohmic Heating and Ultrasound Pretreatments on Quality Attributes

Physical Pretreatments to Enhance Purple-Fleshed Potatoes Drying: Effects of Blanching, Ohmic Heating and Ultrasound Pretreatments on Quality Attributes

Determination of the Effect of Different Drying Methods on the Physicochemical Properties of Potato Powder Using Multivariate Analysis

In this study, powder was obtained from yellow and purple-fleshed potatoes by microwave and hot air drying and the effects of drying methods on the total phenolic compounds, total monomeric anthocyanin, color, antioxidant activity, starch ratio and vitamin C on were determined. It was observed that the microwave drying process caused an increase in bioactive components in purple-colored powder samples, and no significant differences were determined in terms of drying methods in bioactive components in yellow-colored powder samples. When the starch ratio of the samples was examined, it was determined that hot air drying caused a significant increase. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used as multivariate analysis to reveal the effects of different drying techniques and potato varieties on the physicochemical properties of potato powders. As a result, it was found that the physicochemical properties of potato powders differentiated depending on the methods and varieties.

The Impact of Purple-Flesh Potato (Solanum tuberosum L.) cv. "Shadow Queen" on Minor Health Complaints in Healthy Adults: A Randomized, Double-Blind, Placebo-Controlled Study.

The purple-flesh potato (Solanum tuberosum L.) cultivar “Shadow Queen” (SQ) naturally contains anthocyanins. This randomized, double-blind, placebo-controlled study determines whether ingesting purple potatoes increases the number of mesenchymal stem cells (MSC) and improves stress response, a minor health complaint in healthy adults (registration number: UMIN000038876). A total of 15 healthy subjects (ages: 50–70 years) with minor health complaints were randomly assigned to one of two groups. For 8 weeks, the placebo group received placebo potatoes cv. “Haruka” and the test group received test potato cv. SQ containing 45 mg anthocyanin. The MSC count and several stress responses were analyzed at weeks 0 and 8 of the intake periods. The ingestion of a SQ potato did not affect the MSC count but markedly improved psychological stress response, irritability, and depression as minor health complaints compared with “Haruka”. No adverse effects were noted. Hence, an 8-week intake of SQ could improve stress responses.

Comparative effects of vacuum or conventional frying on the polyphenol chemistry and in vitro colon cancer stem cell inhibitory activity of purple-flesh potatoes.

Potatoes are an important food crop that undergo postharvest storage, reconditioning, and cooking. Colored-flesh varieties of potatoes are rich in phenolic acids and anthocyanins. Previous studies have suggested that purple-flesh potatoes can inhibit colon cancer cells in vitro and reduce colon carcinogenesis in vivo. Vacuum frying (VF), as an alternative to conventional frying (CF), reduces fat content and may promote polyphenol retention in potato chips. We examined the impacts of reconditioning (storing at 13°C for 3 weeks following the 90-day cold storage at 7°C) and frying method on phenolic chemistry and in vitro colon cancer stem cell (CCSC) inhibitory activity of purple-flesh potato chips. We found that reconditioned chips exhibited higher total phenolic content (TPC) than nonreconditioned chips. We found that VF chips had lower TPC than CF chips. We observed no interaction between treatments. We found that VF chips had 27% higher total monomeric anthocyanin levels than CF chips, and observed a significant interaction between treatments. We found that VF chips had higher concentrations of caffeic acid (42%-72% higher), malvidin (46%-98% higher), and pelargonidin (55%-300% higher) than CF chips. We found that reconditioning had no effect. We found that VF chips had greater in vitro CCSC inhibitory activity than CF chips. Our results suggest that VF can improve the phytochemical profile and health-related functionality of purple-flesh potato chips, but additional studies are needed to determine if these results translate to the in vivo situation. PRACTICAL APPLICATION: Our current study shows that vacuum frying of purple-flesh potato chips results in higher levels of total monomeric anthocyanins and concentrations of specific polyphenols as compared to chips produced by conventional frying. These differences correlated with better in vitro colon cancer stem cell inhibitory activity. Although additional in vivo studies are needed, our current results suggest that it may be possible for potato processors to improve the health-related functionality of purple-flesh potato chips through the use of vacuum frying.

Genome-wide identification, evolutionary and functional analyses of KFB family members in potato

BackgroundKelch repeat F-box (KFB) proteins play vital roles in the regulation of multitudinous biochemical and physiological processes in plants, including growth and development, stress response and secondary metabolism. Multiple KFBs have been characterized in various plant species, but the family members and functions have not been systematically identified and analyzed in potato.ResultsGenome and transcriptome analyses of StKFB gene family were conducted to dissect the structure, evolution and function of the StKFBs in Solanum tuberosum L. Totally, 44 StKFB members were identified and were classified into 5 groups. The chromosomal localization analysis showed that the 44 StKFB genes were located on 12 chromosomes of potato. Among these genes, two pairs of genes (StKFB15/16 and StKFB40/41) were predicted to be tandemly duplicated genes, and one pair of genes (StKFB15/29) was segmentally duplicated genes. The syntenic analysis showed that the KFBs in potato were closely related to the KFBs in tomato and pepper. Expression profiles of the StKFBs in 13 different tissues and in potato plants with different treatments uncovered distinct spatial expression patterns of these genes and their potential roles in response to various stresses, respectively. Multiple StKFB genes were differentially expressed in yellow- (cultivar ‘Jin-16’), red- (cultivar ‘Red rose-2’) and purple-fleshed (cultivar ‘Xisen-8’) potato tubers, suggesting that they may play important roles in the regulation of anthocyanin biosynthesis in potato.ConclusionsThis study reports the structure, evolution and expression characteristics of the KFB family in potato. These findings pave the way for further investigation of functional mechanisms of StKFBs, and also provide candidate genes for potato genetic improvement.

Effect of Storage Conditions on Biologically Active Compounds in Purple-Fleshed Potatoes

Abstract Potatoes (Solanum tuberosum L.) are an important crop. They are a source of natural phenolic compounds with high biological activity. Stress factors may decrease phenolic concentration and increase concentration of the toxin glycoalkaloid as a result of plant self-protection against stress. The aim of the current study was to evaluate the effect of storage under light on the concentration of biologically active compounds in purple-fleshed potatoes. The purple-fleshed potato variety ‘Blue Congo’ was harvested from test fields of the Institute of Agricultural Resources and Economics in Latvia. Storage under light was performed in a climate chamber ICH110 (Memmert GmbH + Co. KG, Germany) with constant pre-set relative air humidity 85%, temperature +22 °C, and full-spectrum light (Eecoo, 1200 W, LED) intensity of 2000 lux and total time seven days. Total phenolic concentration, antioxidant activity and total glycoalkaloid concentration was measured using spectrophotometry, and moisture was determined according to standard LVS 272:2000. Storage under artificial light of purple-fleshed variety ‘Blue Congo’ potatoes caused decrease of total phenolic concentration and antioxidant activity, no change in moisture level, and increase of total glycoalkaloid concentration.

EFFECT OF RED AND PURPLE FLESH POTATO VARIETIES ON ENZYMATIC DARKENING OF TUBERS AND ANTIOXIDANT PROPERTIES

Background. Colored-flesh potato varieties are becoming more and more popular in Poland. One of the distinctive features of tuber quality is a tendency for the enzymatic darkening of flesh. The aim of the research was to determine the effect of red and purple flesh potato varieties on the change of their color immediately after cutting tubers, one hour and four hours after their cutting, and on the total polyphenol content and antioxidant activity. The research material was three purple flesh potato varieties: Provita, Double Fun, Violet Queen and three red flesh potato varieties: Magenta, Mulberry Beauty, Lily Rose. The raw material came from Polish producers from the 2020 and 2021 growing seasons. Basic chemical composition, total polyphenol content and ABTS+• (μM TROLOX/1g d.m.) and DPPH (μM TROLOX/1g d.m.), as well as antioxidant activity were determined for the potatoes. The color of tuber flesh and its changes were determined calorimetrically using a Minolta CR-200. Results and conclusions. Purple flesh potatoes were characterized by higher total polyphenol content (by 2%) and higher antioxidant activity of ABTS+• and DPPH• (71.2, and 21.0 μM TROLOX/1g d.m. respectively) in comparison to the red varieties (ABTS+• – 60.5 and DPPH – 15.5 μM TROLOX/1g d.m.). The potato varieties tested were characterized by a low tendency for the enzymatic darkening of tubers. The flesh of purple potatoes immediately after cutting was darker (L* 41.8 on average). It was also characterized by a higher share of blue (b* -2.8 on average) and a lower share of red (a* 3.8 on average) than for red flesh potatoes. The flesh of red potatoes after cutting was characterized by a color with a higher proportion of yellow shade (parameter b* was 7.2 on average), which did not change after four hours after cutting.

Acylated anthocyanins: A review on their bioavailability and effects on postprandial carbohydrate metabolism and inflammation.

Anthocyanins, the natural red and purple colorants of berries, fruits, vegetables, and tubers, improve carbohydrate metabolism and decrease the risk factors of metabolic disorders, but their industrial use is limited by their chemical instability. Acylation of the glycosyl moieties of anthocyanins, however, changes the chemical properties of anthocyanins and provides enhanced stability. Thus, acylated anthocyanins are more usable as natural colorants and bioactive components of innovative functional foods. Acylated anthocyanins are common in pigmented vegetables and tubers, the consumption of which has the potential to increase the intake of health-promoting anthocyanins as part of the daily diet. For the first time, this review presents the current findings on bioavailability, absorption, metabolism, and health effects of acylated anthocyanins with comparison to more extensively investigated nonacylated anthocyanins. The structural differences between nonacylated and acylated anthocyanins lead to enhanced color stability, altered absorption, bioavailability, in vivo stability, and colonic degradation. The impact of phenolic metabolites and their potential health effects regardless of the low bioavailability of the parent anthocyanins as such is discussed. Here, purple-fleshed potatoes are presented as a globally available, eco-friendly model food rich in acylated anthocyanins, which further highlights the industrial possibilities and nutritional relevance of acylated anthocyanins. This work supports the academic community and industry in food research and development by reviewing the current literature and highlighting gaps of knowledge.

Effect of Cooking Methods on Bioactivity of Polyphenols in Purple Potatoes

Purple-fleshed potato (Solanum tuberosum L.) is a good dietary source of anthocyanins, flavonols, and polyphenolic acids, mostly chlorogenic acid. The objective of this study was to examine the impacts of cooking methods including boiling, steaming, and the newly developed vacuum-sealed boiling (VSBoil) on extractability and bioactivity of polyphenolic compounds in a purple potato (PP) cultivar, Purple Pelisse. Data showed that boiling and steaming reduced the total polyphenolic content in PP. High-performance liquid chromatography analysis showed that steaming slightly reduced the extractable chlorogenic acid content, while VSBoil increased it. For DPPH free radical scavenging activities, VSBoil and steaming effectively preserved the antioxidant activity of a polyphenol-rich extract of PP, while boiling resulted in a significant reduction compared to raw potato extract. All extracts effectively suppressed bursts of intracellular reactive oxygen species in human colonic epithelial cells upon hydrogen peroxide induction, of which the extract from the VSBoil group showed the highest antioxidant potential. In addition, all extracts showed anti-inflammatory effects in Caco-2 cells induced with tumor necrosis factor-α. In conclusion, the content and bioactivity of extractable polyphenols were largely retained in PP subjected to different cooking processes. VSBoil resulted in the highest content of extractable polyphenolic compounds and bioactivity among tested cooking methods.

Complexation With Polysaccharides Enhanced Polyphenol Gastrointestinal Stability and Activity

Abstract Objectives Fruits and vegetables contain dietary polyphenols and polysaccharides. Accumulating evidence suggests that polyphenol-containing whole foods are protective against inflammation-promoted chronic colonic diseases. However, isolated polyphenols are less stable and may not confer the same gastrointestinal health benefits as that of the whole food matrix. Therefore, we hypothesized that the complexation of anthocyanins, a class of polypheonols, with polysaccharides would enhance colonic concentration and stability of anthocyanins, and attenuate impaired barrier function. Methods In this study, we first extracted the polyphenols from purple-fleshed potatoes and purified them using C18 cartridges into phenolic acid and anthocyanin fractions and confirmed the purity using UPLC. The fractions were complexed with four different polysaccharides (pectin, inulin, starch, cellulose) and their mixture in equal proportions. SEM images were used to visualize the complexation patterns. The stimulated in vitro oral, gastric and small intestine digestion was used to determine the complexation efficiency and stability of anthocyanins. Intestinal permeability was determined using Caco-2/HT29-MTX co-cultures and FITC-dextran. Results Anthocyanins showed significant differences in their complexation pattern with different polysaccharides. After the stimulated in vitro digestion, the % loss of total phenolics and anthocyanins of polysaccharide and anthocyanin complexes were shown here for pectin (16.00 ± 1.5; 47.13 ± 0.5), inulin (58.95 ± 0.1; 80.67 ± 0.09), starch (74.31 ± 3.0; 89.81 ± 0.03), cellulose (76.82 ± 1.5; 72.11 ± 0.1) and mixture (50.32 ± 3.2; 69.90 ± 0.6). Pectin exhibited the best complexation efficiency among different polysaccharides. Caco-2 and HT29-MTX cocultures treated with lipopolysaccharide (LPS) and FITC were used to measure the permeability. Pectin-anthocyanin complex effectively ameliorated LPS-induced increase in cell permeability followed by anthocyanin complexes with the mixture, cellulose, starch, and inulin, respectively. Conclusions These results suggest that pectin is the best candidate for the complexation with anthocyanins for improved gastrointestinal stability and barrier function. Funding Sources USDA-NIFA awards 2016–67,017-29,285 and 2019–67,017-29,258.