Effect of peeling and three cooking methods on the content of selected phytochemicals in potato tubers with various colour of flesh

In vitro biological activity and nutritional evaluation of purple potato (Solanum tuberosum L. var. Vitelotte)

This study aimed to produce functional flour from purple potatoes, which are relatively less known and have limited usage. Purple potatoes (Solanum tuberosum L. var. Vitelotte) and yellow potatoes (Solanum tuberosum L.) used in this study were cultivated in Türkiye. The purple potato flour (PPF) displayed higher values across various parameters, including total phenolic compounds, total flavonoids, total anthocyanins, antioxidant capacity, phenolic content, as well as in-vitro biological activities such as bioaccessibility, anti-diabetic activities, and anti-inflammatory properties, compared to the yellow potato flour (YPF). The mineral content ranking for both flour samples was K > P > Na > Mg > Ca > Fe > Zn > Mn > Cu > Se. The predominant phenolic compounds in PPF were chlorogenic acid, D-( +) malic acid, ferulic acid, and succinic acid. The compounds from anthocyanins found in purple vegetables and fruits, including malvidin chloride, cyanidin chloride, and cyanin chloride, were identified in PPF. PPF exhibited an average in-vitro bioaccessibility of 60%, whereas YPF demonstrated a slightly lower value of 48%. Regarding their in-vitro anti-diabetic activities, PPF showcased an α-amylase inhibition rate averaging 51.67% and an α-glucosidase inhibition rate at 36.22%. As a result of the study, it was observed that purple potato flour was a rich source of total phenolic content, dietary fiber, minerals, antioxidants, and anthocyanins. Considering its gluten-free nature, this functional flour is considered a potential alternative flour source for individuals with celiac disease, opening up new possibilities for various applications in our daily nutrition.

Effects of Household Cooking on Mineral Composition and Retention in Widespread Italian Vegetables

BACKGROUND/OBJECTIVES

The process of cooking food can result in alterations to its nutrient composition due to changes in water content and the destruction or loss of certain micronutrients that occur in response to heat. This study examined the impact of diverse cooking techniques, namely grilling, microwave, and steam, on the macronutrients and minerals of vegetables commonly utilized in Italian cuisine (two varieties of zucchini, eggplants, and potatoes).

METHODS

The proximate composition was determined according to the Association of Official Analytical Chemists (AOAC) methods. The content of the minerals (Ca, K, P, Mg, Na, Fe, Zn, and Mn) was determined via ICP plasma after liquid washing.

RESULTS

Regarding macronutrients, the results revealed a notable difference in the carbohydrate profiles, whereas mineral retention demonstrated considerable heterogeneity. Some minerals, such as Na, Ca, Mn, and Fe, were found to be more prone to significant increases or losses. Moreover, the true retention factor (TR) calculations indicated that microwave cooking resulted in higher retention compared to the other methods for zucchini, while grilling demonstrated higher TR than microwave cooking for eggplants. Potatoes exhibited lower TR values than the other vegetables and their steaming resulted in higher retention than microwave cooking for K, P, Fe, and Zn.

CONCLUSIONS

The results confirm the heterogeneous behaviors of minerals in commonly consumed Italian vegetables subjected to different cooking methods. The data underscore the need for additional research to understand the effects of heat treatments on mineral profiles and to determine specific retention factors linked to various cooking techniques. The significant gap between "true" and "apparent" retention factors, caused by changes in water content during cooking, highlight the need for new experimental data to update and enrich the existing literature on this topic.

Effects of Steaming on Chemical Composition of Different Varieties of Purple-Fleshed Sweetpotato

Purple-fleshed sweetpotatoes (PFSPs) are rich in anthocyanins and are one of the health foods of interest. In this study, the effects of steaming on the anthocyanin, starch, soluble sugar, volatile organic compounds (VOCs) and pasting properties of nine PFSPs from China were investigated. The anthocyanin content of raw PFSP ranged from 9 to 185 mg/100 g. The total starch content decreased and soluble sugar content increased in all purple potatoes after steaming. Among the nine PFSPs varieties, Guangshu20 showed the greatest decrease in starch content (30.61%) and the greatest increase in soluble sugar content (31.12%). The pasting properties affected the taste of the PFSPs, with Shuangpihuang having the lowest peak viscosity (720.33 cP) and Guangzishu12 having the highest peak viscosity (2501.67 cP). Correlation studies showed that the anthocyanin content and pasting properties were negatively correlated with most of the sensory indicators, whereas the soluble sugar content of steamed PFSPs was significantly positively correlated with sweetness. A total of 54 VOCs were identified in this study, and aldehydes and terpenoids were the major VOCs in PFSPs. This study provides a theoretical basis for the processing of different PFSP varieties.

Updated aspects of alpha-Solanine as a potential anticancer agent: Mechanistic insights and future directions

Cancer remains a critical global health challenge, with limited progress in reducing mortality despite advancements in diagnosis and treatment. The growing resistance of tumors to existing chemotherapy exacerbates this burden. In response, the search for new anticancer compounds from plants has intensified, given their historical success in yielding effective treatments. This review focuses on α-solanine, a glycoalkaloid primarily derived from potato tubers and nightshade family plants, recognized for its diverse biological activities, including anti-allergic, antipyretic, anti-inflammatory, anti-diabetic, and antibiotic properties. Recently, α-solanine has gained attention as a potential anticancer agent. Utilizing resources like PubMed/MedLine, ScienceDirect, Web of Science, Scopus, the American Chemical Society, Google Scholar, Springer Link, Wiley, and various commercial websites, this review consolidates two decades of research on α-solanine's anticancer effects and mechanisms against nine different cancers, highlighting its role in modulating various signaling pathways. It also discusses α-solanine's potential as a lead compound in cancer therapy. The abundant availability of potato peel, often discarded as waste or sold cheaply, is suggested as a sustainable source for large-scale α-solanine extraction. The study concludes that α-solanine holds promise as a standalone or adjunctive cancer treatment. However, further research is necessary to optimize this lead compound and mitigate its toxicity through various strategies.

Transcriptomic and Metabolic Analysis Reveals Genes and Pathways Associated with Flesh Pigmentation in Potato (Solanum tuberosum) Tubers

Anthocyanins, flavonoid pigments, are responsible for the purple and red hues in potato tubers. This study analyzed tubers from four potato cultivars-red RR, purple HJG, yellow QS9, and white JZS8-to elucidate the genetic mechanisms underlying tuber pigmentation. Our transcriptomic analysis identified over 2400 differentially expressed genes between these varieties. Notably, genes within the flavonoid biosynthesis pathway were enriched in HJG and RR compared to the non-pigmented JZS8, correlating with their higher levels of anthocyanin precursors and related substances. Hierarchical clustering revealed inverse expression patterns for the key genes involved in anthocyanin metabolism between pigmented and non-pigmented varieties. Among these, several MYB transcription factors displayed strong co-expression with anthocyanin biosynthetic genes, suggesting a regulatory role. Specifically, the expression of 16 MYB genes was validated using qRT-PCR to be markedly higher in pigmented HJG and RR versus JZS8, suggesting that these MYB genes might be involved in tuber pigmentation. This study comprehensively analyzed the transcriptome of diverse potato cultivars, highlighting specific genes and metabolic pathways involved in tuber pigmentation. These findings provide potential molecular targets for breeding programs focused on enhancing tuber color.

Assessment of the Content of Glycoalkaloids in Potato Snacks Made from Colored Potatoes, Resulting from the Action of Organic Acids and Thermal Processing

Glycoalkaloids (TGAs, total glycoalkaloids), toxic secondary metabolites, are found in potatoes (110-335 mg·kg-1 DW), mainly in the peel. Colorful, unpeeled potatoes are an innovative raw material for the production of snacks which are poorly tested in terms of their glycoalkaloid content. Third-generation snacks and French fries made from red-fleshed Mulberry Beauty (MB) and purple-fleshed Double Fun (DF) potatoes were produced with the use of 1% solutions of ascorbic, citric, lactic, malic, and tartaric acids to stabilize the structure of anthocyanins in the raw material and maintain their color in obtained products. The influence of the type of acid and thermal processes, like frying, microwaving, and baking, on the content of glycoalkaloids in ready-made products was examined. Only 0.45-1.26 mg·100 g-1 of TGA was found in pellet snacks and 1.32-1.71 mg·100 g-1 in French fries. Soaking blanched potatoes in organic acid solution reduced the α-chaconine content by 91-97% in snacks and by 57-93% in French fries in relation to the raw material to the greatest extent after the use of malic acid and the DF variety. The effect of lactic and citric acid was also beneficial, especially in the production of baked French fries from MB potatoes.

Effect of Microwave-Based Dry Blanching on Drying of Potato Slices: A Comparative Study

Microwave (MW)-based dry blanching can inactivate oxidative enzymes like peroxidase (POD) and polyphenol oxidase (PPO) rapidly and retain a higher amount of water-soluble nutrients, like ascorbic acid. This study compared the MW-based dry blanching of potato slices of various thicknesses (5, 8, and 10 mm) with conventional methods (water and steam blanching). The time required for water and steam blanching was longer than that required for MW blanching. Potato slices of 10 mm thickness required a longer blanching duration compared with slices of a lesser thickness (5 and 8 mm). The MW-blanched samples (77.37-83.5%) retained a higher content of ascorbic acid, followed by steam-blanched (69.15-74.92%) and water-blanched (67.18-71.54%) samples. The Page, modified Page, Midilli-Kucuk, and Hii, Law, and Cloke models predicted the thin layer drying of potato slices (5 mm thickness) better with a higher coefficient of determination values (0.9607-0.9976) compared to Fick's and Exponential models (0.8942-0.9444).

Physicochemical parameters, sensory profile and concentration of volatile compounds and anthocyanins in beers brewed using potato variety with purple flesh

In the recent years, beer brewers are experimenting with using various substrates, other than traditional barley malt, water, hops, and yeast for beer production, because new adjuncts to the beer brewing can add new sensory and functional properties to this beverage. Novel potatoes with purple or red-colour flesh are a good and cheap starch source and are rich in bioactive components, which could increase the nutritive value of the produced beer. The aim of the study was to determine whether some part of barley malt can be replaced by the potatoes of purple-colour flesh and assessment of properties of such beer. Beer samples showed increased antioxidant activity, higher concentration of anthocyanins and polyphenol compounds, as well as modified composition of volatiles and lower ethanol content. Beer produced with the addition of 30% of purple potatoes showed acceptable organoleptic qualities in the sensory analysis.

Content and Stability of Hydroxycinnamic Acids during the Production of French Fries Obtained from Potatoes of Varieties with Light-Yellow, Red and Purple Flesh

Potatoes with different flesh colours contain health-promoting compounds, i.e., hydroxycinnamic acids, which vary in content and stability during thermal processing. The aim of this study was to determine the effect of the technological stages of the production of French fries obtained from potatoes with different flesh colours on the content of selected hydroxycinnamic acids, as well as the stability of these acids, their percentage in sum of acids, total phenolic content and antioxidant activity (ABTS, DPPH) in semi-products and ready-to-eat products. During the production of French fries, samples of unpeeled, peeled, cut, blanched, pre-dried and fried potatoes were collected. After peeling, coloured potatoes, especially purple ones, had more hydroxycinnamic (5-CQA, 4-CQA, 3-CQA and CA) acids remaining in the flesh than in the flesh of the light-yellow variety. The greatest losses of the determined hydroxycinnamic acids, regardless of the given potato's variety, were caused by the stage of pre-drying (about 91%) and frying (about 97%). The French fries obtained from the potatoes with coloured flesh, especially those with purple flesh, had the highest amount of stable 5-CQA and 4-CQA acids as well as 3-CQA acid, already absent in light-yellow French fries. The least stable acid was CA acid, which was not found in any of the ready snacks.

Cooking at home to retain nutritional quality and minimise nutrient losses: A focus on vegetables, potatoes and pulses

Cooking at home has experienced a decline in many countries since the mid-20th century. As rates of obesity have increased, there has been an emphasis on more frequent home cooking, including its incorporation into several food-based dietary guidelines around the world as a strategy to improve dietary quality. With the recent trend towards the adoption of diets richer in plant-based foods, many consumers cooking at home may now be cooking plant foods such as vegetables, potatoes and pulses more often. It is, therefore, timely to explore the impact that different home cooking methods have on the range of nutrients (e.g. vitamin C and folate) and bioactive phytochemicals (e.g. carotenoids and polyphenols) that such plant foods provide, and this paper will explore this and whether advice can be tailored to minimise such losses. The impact of cooking on nutritional quality can be both desirable and/or undesirable and can vary according to the cooking method and the nutrient or phytochemical of interest. Cooking methods that expose plant foods to high temperatures and/or water for long periods of time (e.g. boiling) may be the most detrimental to nutrient content, whereas other cooking methods such as steaming or microwaving may help to retain nutrients, particularly those that are water-soluble. Dishes that use cooking liquids may retain nutrients that would have been lost through leaching. It may be helpful to provide the public with more information about better methods to prepare and cook plant foods to minimise any nutrient losses. However, for some nutrients/phytochemicals the insufficient and inconsistent research findings make clear messages around the optimal cooking method difficult, and factors such as bioaccessibility rather than just quantity may also be important to consider.

Household Processing Methods and Their Impact on Bioactive Compounds and Antioxidant Activities of Sweetpotato Genotypes of Varying Storage Root Flesh Colours

Sweetpotato storage roots, peeled and unpeeled, of varying flesh colours (white, cream, yellow, pale orange, deep orange, and purple) were spectrophotometrically evaluated for their bioactive compounds and antioxidant activities. Roots were boiled, steamed, baked, fried, or microwaved. The unpeeled roots had relatively higher (p < 0.001) bioactive compounds and antioxidant activities than the peeled ones. All cooking methods increased phenolic compounds, flavonoids, and tannins in all genotypes. Significant losses of total carotenoids occurred with all cooking methods (ranging from 24.18 to 172.76 µg/g in raw sweetpotatoes vs. 10.06 to 118.17 µg/g in cooked ones; p < 0.001), except the deep-orange-fleshed genotype, in which frying slightly increased carotenoids from 269.81 to 304.74 µg/g. Microwaving retained 69% vitamin C in the cream-fleshed one, the highest among the cooking methods. Anthocyanins decreased with baking and frying in the purple-fleshed one but increased with other methods; microwaving being highest at 13.9% (17.43 mg/g). While the 2,2′-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid antioxidant activity decreased with all cooking techniques in some genotypes, ferricyanide-reducing antioxidant potential increased. The retention of bioactive compounds in sweetpotato storage roots depends on the processing method. Thus, to obtain the most health benefits, consumers should use different cooking methods but retain the peels.

Chemical composition and technofunctional properties of carrot (Daucus carota L.) pomace and potato (Solanum tuberosum L.) pulp as affected by thermomechanical treatment

Fiber rich by-products derived from primary agri-food production such as carrot pomace and potato pulp are available in large quantities, but their functional properties do not necessarily meet the requirements for use in specific food applications. Thermomechanical treatment (extrusion) of carrot pomace and potato pulp changes both dietary fiber polysaccharide structures and technofunctionality of the materials. Solubility of dietary fiber constituents changes, resulting in higher levels of water- and ethanol-soluble poly-/oligosaccharides. On a structural level, particularly arabinans and galactans as neutral side chains of type I rhamnogalacturonan were degraded under thermomechanical stress. Galacturonic acid portions (preferably from homogalacturonan or rhamnogalacturonan I) and their degree of methylation were also negatively affected. On a functional level, water absorption of potato pulp increased up to three times following extrusion, whereas water absorption of carrot pomace decreased with extrusion processing. The observed, enhanced swelling behavior for extruded carrot pomace was accompanied by higher complex viscosity of the dispersions. Swelling of potato pulp particles increased largely (up to 25 times) following extrusion, resulting in highly viscous pastes. Phytochemicals were retained up to 50%, heat-induced contaminants were formed only to a small extent (up to 8.1 mg 5-hydroxymethylfurfural·kg− 1 dry matter for carrot pomace; up to 71 µg acrylamide·kg− 1 dry matter for potato pulp).

Graphical abstract

Metabolomic Characterization of Pigmented and Non-Pigmented Potato Cultivars Using a Joint and Individual Variation Explained (JIVE)

Potatoes (Solanum tuberosum L.) are one of the most valuable agricultural crops, and the flesh of these tubers provides various classes of healthy compounds important for human nutrition. This work presents the results of a joint analysis of different chemical classes of compounds which provided insights on the metabolic characterization of pigmented and non-pigmented potato varieties collected from Italy. The identification of common or individual metabolic characteristics across the omic datasets (antioxidants, total polyphenolic content, polyphenols, and sugars) is conducted by Joint and Individual Variation Explained (JIVE), a data fusion multivariate approach. The common part of the multivariate model allowed the separation between non-pigmented and pigmented samples. Polyphenolic compounds were mainly responsible for the separation between purple-fleshed and red-skinned potatoes. An additional detailed analysis of the anthocyanin composition, including the acylated anthocyanins, allowed to pinpoint the diversities between the pigmented potato groups. Furthermore, the presence of an appreciable amount of hydroxycinnamic acids and anthocyanins in the purple-fleshed varieties, which are also characterized by a lower content of sugars, is found. Our results provide scientific evidence for the promotion of promising potato cultivars, which are characterized by a remarkable amount of various health benefit compounds.

Deep-frying purple potato Purple Majesty using sunflower oil: effect on the polyphenols, anthocyanins and antioxidant activity

The potato is a root vegetable native to the Americas; it consists of the starchy tuber of the plant Solanum tuberosum. There are many varieties, and the flesh can have different colour ranging from yellow to red and purple. Coloured varieties have a denser texture and slightly nuttier, earthier flavour than other potatoes. The desirable quality characteristics of potatoes depends on the intended use, and the acceptability of raw potatoes is determined by size, shape, colour, and the quality of can be evaluated in terms of colour, flavour, and texture. Deep-frying is the century-old and it is among the most common cooking processes, still being used to prepare a variety of food products on both industrial and domestic scales. Frying the potatoes is among the tastiest and appreciated way to cook this vegetable. Purple fleshed potatoes are widely considered one of the best-tasting purple potatoes varieties, they have a nice taste and add colour to a meal. They are a source of beneficial health compounds which makes them interesting as functional food. The anthocyanins present in the Purple Majesty variety are interesting for their health promoting abilities, anti-oxidative activity, and even other health beneficial effects, e.g. anti-influenza virus activity, and anti-stomach cancer activity. The aim of this study has been to assess the effect of deep-frying of purple potato Purple Majesty using sunflower oil on the polyphenols, anthocyanins and to evaluate the antioxidant activity of the cooked matrix compared to the fresh one. The results seem to suggest that the healthy characteristics of this functional food are retained after the cooking by frying.

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Purple potato “Purple Majesty” is rich in antioxidants and anthocyanins.

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Deep frying in sunflower oil affects positively the antioxidant activity.

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The anthocyanins increase their amount in the frying time range.

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Polyphenols amount decreases during frying time.

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The ferulic and gallic acids seem to increase their amount after 48 h of frying.

Updated insights into anthocyanin stability behavior from bases to cases: Why and why not anthocyanins lose during food processing

Anthocyanins have received considerable attention for the development of food products with attractive colors and potential health benefits. However, anthocyanin applications have been hindered by stability issues, especially in the context of complex food matrices and diverse processing methods. From the natural microenvironment of plants to complex processed food matrices and formulations, there may happen comprehensive changes to anthocyanins, leading to unpredictable stability behavior under various processing conditions. In particular, anthocyanin hydration, degradation, and oxidation during thermal operations in the presence of oxygen represent major challenges. First, this review aims to summarize our current understanding of key anthocyanin stability issues focusing on the chemical properties and their consequences in complex food systems. The subsequent efforts to examine plenty of cases attempt to unravel a universal pattern and provide thorough guidance for future food practice regarding anthocyanins. Additionally, we put forward a model with highlights on the role of the balance between anthocyanin release and degradation in stability evaluations. Our goal is to engender updated insights into anthocyanin stability behavior under food processing conditions and provide a robust foundation for the development of anthocyanin stabilization strategies, expecting to promote more and deeper progress in this field.

Genetic Diversity and Health Properties of Polyphenols in Potato

Polyphenol is one of the most essential phytochemicals with various health benefits. Potato (Solanum tuberosum L.) is known as a potential source of polyphenols, and also has health benefits in which phenolic acids, such as chlorogenic, ferulic acid, caffeic acid, and flavonoids, such as anthocyanins, sustainably play the most significant role. Almost every polyphenol contributes to various biological activities. In this review, we collected comprehensive information concerning the diversity of polyphenols in potatoes, and the effects of post-harvest processing and different cooking methods on the bioavailability of polyphenols. To achieve maximum health benefits, the selection of potato cultivars is necessary by choosing their colors, but various cooking methods are also very important in obtaining the maximum concentration of polyphenolic compounds. The health properties including major biological activities of polyphenols, such as antioxidant activity, anticarcinogenic activity, anti-inflammatory activity, anti-obesity activity, and antidiabetic activity, have also been summarized. All these biological activities of polyphenols in potatoes might be helpful for breeders in the design of new varieties with many health benefits, and are expected to play a vital role in both pharmaceutical and nutraceutical industries.

Changes in structure and phenolic profiles during processing of steamed bread enriched with purple sweetpotato flour

Purple-fleshed sweetpotato is a rich source of antioxidants such as polyphenols. Chinese steamed bread (CSB) is a popular food product for many people. The effect of CSB making process on the structure and phenolic profiles of CSB enriched with purple sweetpotato flour (PSPF) at different concentrations was investigated. The mixing process greatly reduced the gluten strength due to the incorporation of PSPF. The addition of PSPF induced extensive structural modification on CSB due to the starch-polyphenol and protein-polyphenol interactions. The total phenolic contents, in vitro antioxidant activity, and the contents of hydroxycinnamic acid derivatives were decreased by fermentation and proofing, but they were increased after steaming and storage. The anthocyanins were significantly degraded during the CSB making process. The textural and structural properties of CSB were significantly affected by the PSPF substitutions. The results of this study are useful to develop functional CSB with improved nutritional quality and phenolic profiles.

Biochemical Characterization and Effects of Cooking Methods on Main Phytochemicals of Red and Purple Potato Tubers, a Natural Functional Food

Potato is a staple food crop and an important source of dietary energy. Its tubers contain several essential amino acids, vitamins, minerals and phytochemicals that contribute to the nutritional value of this important product. Recently, scientific interest has focused on purple and red potatoes that, due to the presence of anthocyanins, may be considered as natural powerful functional food. The aim of this study was to evaluate the characteristics of pigmented varieties, the types of anthocyanins accumulated and the level of both beneficial phytochemicals (vitamin C and chlorogenic acids, CGAs) and anti-nutritional compounds (glycoalkaloids) following various cooking methods. The analyses described the presence of a mix of several acylated anthocyanins in pigmented tubers along with high level of CGA. The amount of antioxidants was differently affected by heat treatments according to the type of molecule and the cooking methods used. In some cases, the beneficial compounds were made more available by heat treatments for the analytical detection as compared to raw materials. Data reported here describe both the agronomic properties of these pigmented varieties and the effects of food processing methods on bioactive molecules contained in this natural functional food. They may provide useful information for breeders aiming to develop new varieties that could include desirable agronomical and industrial processing traits.

Pigmented Potatoes: A Potential Panacea for Food and Nutrition Security and Health?

Although there are over 4000 potato cultivars in the world, only a few have been commercialized due to their marketability and shelf-life. Most noncommercialized cultivars are pigmented and found in remote regions of the world. White-fleshed potatoes are well known for their energy-enhancing complex carbohydrates; however, pigmented cultivars are potentially high in health-promoting polyphenolic compounds. Therefore, we reveal the comprehensive compositions of pigmented cultivars and associated potential health benefits, including their potential role in ameliorating hunger, food, and nutrition insecurity, and their prospects. The underutilization of such resources is a direct threat to plant-biodiversity and local traditions and cultures.

The Influence of the Production Process on the Anthocyanin Content and Composition in Dried Potato Cubes, Chips, and French Fries Made from Red-Fleshed Potatoes

The stability of acylated anthocyanins is still a new and unexplored subject of study. The changes in the contents of individual anthocyanins in colored-flesh potato tubers during processing have rarely been addressed in the literature. The aim of the present study was to determine how anthocyanin degradation and profiles are influenced in potatoes of the red-fleshed Herbie 26 variety by different methods of processing. Potato samples were divided into four categories to be analyzed, namely, raw material, potato cubes, French fries, and chips. The dried cubes, French fries, chips, semi-finished products, and finished products, obtained through laboratory processing, were examined for anthocyanin content and composition. The production process of cubes, chips, and French fries led to losses of the examined anthocyanins; however, these losses differed depending on the technological stage. The greatest losses of these compounds were determined after the final production processes, i.e., pre-frying, frying, and drying. Chip production led to the lowest losses of anthocyanins. Omitting the blanching stage in chip production allowed the retention of more anthocyanins. Pelargonidin-3-feruloylrutinoside-5-glucoside, having the highest percentage in the raw material (approximately 50%), followed by pelargonidin-3-caffeoylrutinoside-5-glucoside, proved to be the most thermally stable.

Influence of Heat Treatments on the Content of Bioactive Substances and Antioxidant Properties of Sweet Potato (Ipomoea batatas L.) Tubers

Heat treatment can affect the bioactive compounds in sweet potato (SP). In this work, we monitored the influence of heat treatment (boiling, steaming, microwaving, and baking) on the total polyphenols content (TPC), total antioxidant capacity (TAC), total anthocyanins content (TANTC), and phenolics acids (chlorogenic (CGA), neochlorogenic (neo-CGA), and trans-ferulic (tFA)) in two SP varieties grown in Slovakia and Croatia. TPC, TAC, and TANT were determined spectrophotometrically and phenolic acids by HPLC. TPC ranged from 576 (Beauregard, Croatia; Be/HR) to 3828 (414-purple, Slovakia; Pu/SK) mg/kg DW in the raw SP tubers. After heat treatment, TPC increased, most in steamed SP (8438 mg GAE/kg DW; Pu/SK), while only in boiled SP (Be/HR), TPC decreased (353 mg GAE/kg DW). TAC varied from 0.848 (Be/HR) to 8.67 (Pu/HR) (μmol TE/g DW) in raw SP. The TAC increased by heat treatment (max. 14.2 μmol TE/g DW; cooking Be/SK), except for Pu/HR. The TANT ranged from 151 (raw Pu/SK) to 1276 (microwaved Pu/SK) mg CyE/kg FW. Heat treatment had a negative effect on phenolic acid content; the largest reduction was after boiling: CGA by 29% (Pu/SK), neo-CGA by 69% (Pu/HR), and tFA by 29% (Be/HR). The influence of heat treatment on the monitored quantities is not definite.

Risk assessment of glycoalkaloids in feed and food, in particular in potatoes and potato-derived products

The European Commission asked EFSA for a scientific opinion on the risks for animal and human health related to the presence of glycoalkaloids (GAs) in feed and food. This risk assessment covers edible parts of potato plants and other food plants containing GAs, in particular, tomato and aubergine. In humans, acute toxic effects of potato GAs (α-solanine and α-chaconine) include gastrointestinal symptoms such as nausea, vomiting and diarrhoea. For these effects, the CONTAM Panel identified a lowest-observed-adverse-effect level of 1 mg total potato GAs/kg body weight (bw) per day as a reference point for the risk characterisation following acute exposure. In humans, no evidence of health problems associated with repeated or long-term intake of GAs via potatoes has been identified. No reference point for chronic exposure could be identified from the experimental animal studies. Occurrence data were available only for α-solanine and α-chaconine, mostly for potatoes. The acute dietary exposure to potato GAs was estimated using a probabilistic approach and applying processing factors for food. Due to the limited data available, a margin of exposure (MOE) approach was applied. The MOEs for the younger age groups indicate a health concern for the food consumption surveys with the highest mean exposure, as well as for the P95 exposure in all surveys. For adult age groups, the MOEs indicate a health concern only for the food consumption surveys with the highest P95 exposures. For tomato and aubergine GAs, the risk to human health could not be characterised due to the lack of occurrence data and the limited toxicity data. For horses, farm and companion animals, no risk characterisation for potato GAs could be performed due to insufficient data on occurrence in feed and on potential adverse effects of GAs in these species.

Analysis of Environmental Conditions Effect in the Phytochemical Composition of Potato (Solanum tuberosum) Cultivars

Crop productivity and food quality are affected by environmental conditions. The objective of this work was to evaluate the effect of the environment on the concentration of phytochemical components in several potato (Solanum tuberosum) cultivars. The content of vitamin C (ascorbic acid, AA), the total carotenoids content (TCC), the total polyphenols content (TPC), and the total anthocyanins content (TAC) of 11 potatoes varieties grown in Ecuador (Cutuglahua, Pujilí, and Pilahuín) was measured by the spectrophotometric method. The antioxidant capacity (AC) of potato cultivars was evaluated by the ABTS method. The AA concentration ranged between 12.67 to 39.49 mg/100g fresh weight (FW), the TCC ranged between 50.00 and 1043.50 μg/100g FW, the TPC ranged between 0.41 and 3.25 g of gallic acid equivalents (GAE)/kg dry weight (DW), the TAC ranged between 2.74 and 172.53 μg/g FW and finally the AC ranged between 36.80 and 789.19 μg of trolox equivalents (TE)/g FW. Genotypes (G), location (L), and interaction (G x L) were significant at p < 0.01. The genotype (G) showed a greater variation in the phytochemical contents. AA and TPC showed the highest correlation with the AC. A selection of genotypes with these characteristics can be used to develop germplasms with a high AC.

Current intake levels of potatoes and all-cause mortality in China: A population-based nationwide study

OBJECTIVE

Current levels of potato consumption in relation to mortality in Chinese people remains unknown. The aim of this study was to investigate the intakes of total potatoes, fried potatoes, non-fried potatoes, and sweet potatoes as dietary carbohydrate sources in relation to all-cause mortality in the China Health and Nutrition Survey (CHNS).

METHODS

Overall 14 117 participants ≥20 y of age were included, with a median follow-up of 14 y. The cumulative average consumption of potatoes and other foods were calculated and validated using weighing methods in combination with 3-d, 24-h dietary recalls at both household and individual levels. Hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards regression models after multivariate adjustment.

RESULTS

We documented 1007 deaths among the participants. The low and moderate intakes of total potatoes, fried potatoes, and non-fried potatoes were inversely associated with mortality. Compared with non-consumers, the intakes of total potatoes (HR, 0.48; 95% CI, 0.38-0.59), fried potatoes (HR, 0.44; 95% CI, 0.34-0.56), and non-fried potatoes (HR, 0.47; 95% CI, 0.37-0.61) at low consumption levels were most significantly related to lower mortality. Sweet potato consumption was inversely associated with mortality after full adjustment (HR, 0.82; 95% CI, 0.69-0.96) compared with non-consumers. Substituting grains and mixed beans for potatoes with equal amounts at high consumption levels strengthened the inverse associations.

CONCLUSION

In the CHNS, current low and moderate, but not high levels of total potato and fried/non-fried potato consumption as well as sweet potato consumption were inversely associated with all-cause mortality among Chinese people.

Genomics-Integrated Breeding for Carotenoids and Folates in Staple Cereal Grains to Reduce Malnutrition

Globally, two billion people suffer from micronutrient deficiencies. Cereal grains provide more than 50% of the daily requirement of calories in human diets, but they often fail to provide adequate essential minerals and vitamins. Cereal crop production in developing countries achieved remarkable yield gains through the efforts of the Green Revolution (117% in rice, 30% in wheat, 530% in maize, and 188% in pearl millet). However, modern varieties are often deficient in essential micronutrients compared to traditional varieties and land races. Breeding for nutritional quality in staple cereals is a challenging task; however, biofortification initiatives combined with genomic tools increase the feasibility. Current biofortification breeding activities include improving rice (for zinc), wheat (for zinc), maize (for provitamin A), and pearl millet (for iron and zinc). Biofortification is a sustainable approach to enrich staple cereals with provitamin A, carotenoids, and folates. Significant genetic variation has been found for provitamin A (96-850 μg and 12-1780 μg in 100 g in wheat and maize, respectively), carotenoids (558-6730 μg in maize), and folates in rice (11-51 μg) and wheat (32.3-89.1 μg) in 100 g. This indicates the prospects for biofortification breeding. Several QTLs associated with carotenoids and folates have been identified in major cereals, and the most promising of these are presented here. Breeding for essential nutrition should be a core objective of next-generation crop breeding. This review synthesizes the available literature on folates, provitamin A, and carotenoids in rice, wheat, maize, and pearl millet, including genetic variation, trait discovery, QTL identification, gene introgressions, and the strategy of genomics-assisted biofortification for these traits. Recent evidence shows that genomics-assisted breeding for grain nutrition in rice, wheat, maize, and pearl millet crops have good potential to aid in the alleviation of micronutrient malnutrition in many developing countries.

Carbohydrate and bioactive compounds composition of starchy tropical fruits and tubers, in relation to pre and postharvest conditions: A review

In some tropical countries, people are suffering from both undernourishment and noncommunicable disorders, such as overweight/obesity. Starchy tropical fruits and tubers are of particular interest for their carbohydrate content and for the micronutrients they provide. The present study summarizes the content in carbohydrate, phenolics, carotenoids, and vitamin C, as well as the antioxidant activity of a wide range of tropical fruits and tubers. The energy content of fruits and tubers studied is in the range of 1,200 to 1,800 kJ/100 g of dry weight. They are thus important staple foods and, due to their diversity and seasonality, they can provide energy all year long by alternating the resources in the human diet. Starchy fruit and tuber crops have antiobesity properties as they are bulky, rich in moisture, and contain less than 2% of fat. Noncolored fruit and tubers provide total phenolics at about 20 to 140 mEq/100 g fresh weight. They thus have a high antioxidant capacity, as related to their total phenolic content but also to the presence of carotenoids, such as lutein, mostly in Dioscorea bulbifera and cocoyam. Yellow and orange-fleshed varieties contain more total phenolics and also more provitamin A carotenoids than noncolored fleshed ones. The contents in total phenolic and carotenoid greatly vary with the species and variety. The influence of pre and postharvest conditions on micronutrient content is discussed. Further studies on new processing methods are needed to maximize polyphenols and carotenoids retention in the foods and increase the bioaccessibility of these compounds. PRACTICAL APPLICATION: This paper provides information on the nutritional quality of starchy tropical fruits and tubers. Nutritional quality is studied from the point of view of providing energy and bioactive compounds. The paper aims to promote the use of local resources in tropical areas, which could ultimately limit the adverse effects of food globalization on noncommunicable disorders. It could also lead to tropical countries being less dependent on food imports.

Degradation and regulation of edible flower pigments under thermal processing: a review

More and more consumers are aware of the potential health benefits of edible flower pigments. With the increased popularity and broader application of edible flower pigments, their degradation under thermal processing has attracted researchers' attention, because this may affect the pigment functionalities. At high temperature of thermal processing, polyene pigments are easy to oxidize, degrade and isomerize due to high unsaturation, and phenolic pigments may hydrolyze and isomerize of glycosides, which will result in the decreased antioxidant activity and eating quality, and discounted potential health benefits. Therefore, it is very important to understand the degradation mechanisms of edible flower pigments under thermal processing, which is important to develop corresponding control methods to minimize such negative impacts. This review paper discussed the recent development in the degradation mechanisms and regulation methods of edible flower pigments under thermal processing.

Liquid Chromatography Mass Spectrometry Quantification of α-solanine, α-chaconine, and Solanidine in Potato Protein Isolates

For potato proteins to be used as a food ingredient, the level of natural potato defense substances, the glycoalkaloids (GAs), should be limited. In this work, a method is developed for quantification of the two major potato GAs, α-solanine and α-chaconine, as well as for their aglycon form, solanidine, using liquid chromatography–mass spectrometry single quadrupole in single ion monitoring mode. Standard solutions of GA and a food-grade potato protein powder was used to validate the method. A linear correlation between GA concentration and the ion intensity of >0.995 was obtained for all standard solutions. Recovery of GA in spiked samples was within the range 82%–106%. The method for GA quantification was applied to a variety of potato protein isolates. The results showed that total GA increased during the storage of the potatoes. Washing the potato protein isolates using water at a sufficient level was shown to be able to reduce the amount of GA below the threshold of 150 µg g⁻¹, as needed for human consumption.

The effect of peeling and cooking processes on nutrient composition of Oromo dinich (Plectranthus edulis) tuber

The effects of peeling and cooking processes (boiling, steaming and baking) on the proximate, amino acids, mono, and disaccharides content of Oromo dinich (Plectranthus edulis) tubers from selected landraces were investigated. The effect of peeling on the crude protein, reducing sugars and sucrose content of the tuber was not consistent across the landraces. Crude protein reduced in landraces DHSer, IWsh, DGArr, and DGArw but increased in landrace CWsh. Reducing sugars (fructose, glucose, and maltose) increase in landraces LWsh, CWsh, DGArr, and DOJiw but reduced in landrace DOSu. Sucrose reduced in landraces IWsh and LWsh but increased in landrace CWsh on dry matter basis. Peeling significantly reduced the dry matter, ash and crude fiber content of the tubers. Dry matter reduced in landraces CWsh, DGArr, and DGArw; ash reduced in landraces DHSer and DGArw; crude-fiber reduced in landraces DOSu, DOSer, LWsh, CWsh, DGArr, and DGArw. On contrary, peeling significantly increased the crude fat, sum of total amino acids content and energy density of the tubers. Crude fat increased in landrace DOSu, IWsh, CWsh, DGArr, and DOJiw. Sum of total amino acids increased in landraces DOSu, DOJiw, and DGArw. Energy density (KJ/100 g dm) increased in landraces DOSu, DHSer, IWsh, and DOJiw. Boiling and steaming significantly increased the ash content of the tubers in landrace LWsh. Steaming and baking significantly increased crude fiber in landraces IWch and CWsh, and carbohydrate content of the tubers in landrace LWsh. Boiling, steaming and baking significantly reduced the crude fiber and the energy density of the tubers in landrace LWsh. Baking significantly reduced the moisture content of the tubers in landraces IWch, LWsh and CWsh. Boiling significantly reduced reducing sugars and crude fat content of the tubers in landraces IWch, LWsh and CWsh. The reduction in reducing sugar and crude fat content most likely is due to leaching and the presence of essential oils respectively. Thus to get the best possible nutritional benefits from P.edulis tubers, cooking with their skin under optimized operation recommended.

Determination of citric acid pretreatment effect on nutrient content, bioactive components, and total antioxidant capacity of dried sweet potato flour

Orange flashed sweet potatoes are rich and inexpensive source of diet and antioxidants. The purpose of this study was to evaluate the effects of CA pretreatments and convective hot air drying temperature on proximate composition, bioactive components, and total antioxidant capacity of flour of five orange flashed sweet potato varieties. Moisture, protein, ether extract, ash, carbohydrate, fiber, β-carotene, total phenolic compounds, and total antioxidant capacity in the dried flour samples were evaluated and reported in the range of 4.1-7.4%, 2.4-4.2%, 1.2-1.1.8%, 2.2-3.2%, 82.7-87.1%, 1.3-1.8%, 35.5-91.6 mg/100 g, 49.8-107.9 mg GAE/100 g, and 27.3-85.4%, respectively. The interaction effects of varieties, drying temperature, and CA concentration were significant (p ˂ 0.05) except for fiber. Kulto and SPK006/6/6 performed better for most of the parameters studied followed by SPK00/06. For almost all varieties, samples dried at 55°C and after treated in 3% CA solution had the highest percentage in terms of proximate composition, bioactive components, and total antioxidant capacities.

Improved analysis of anthocyanins and vitamin C in blue-purple potato cultivars

Methods were optimized for extraction and quantification of anthocyanins (ACY) and vitamin C in potatoes. Acidified aqueous methanol (70%) was the optimal extraction solvent and freeze-drying significantly improved the extraction yield of ACY. The content of ACY varied widely in five potato cultivars from 0.42 to 3.18mg/g dry weight, with the latter being the highest value found in the Finnish cultivar 'Synkeä Sakari'. Compared with dithiothreitol (DTT), tris(2-carboxyethyl) phosphine hydrochloride (TCEP) was more efficient in reducing dehydroascorbic acid (DHA) to ascorbic acid (AA) and for quantifying the content of total ascorbic acid (TAA). For raw potatoes, quantification of TAA after treatment with TCEP was more reliable than a direct analysis of AA, whereas AA can be analyzed directly in steam-cooked samples. The TAA contents in the three potato cultivars were around 0.30-0.35mg/g dry weight. The loss of AA in steam cooking was 24%.

Isolation and chemoenzymatic treatment of glycoalkaloids from green, sprouting and rotting Solanum tuberosum potatoes for solanidine recovery

The estimation of glycoalkaloids in the flesh of different types of decayed potatoes was evaluated. The results showed that turned green and also sprouting or rotting potato flesh contain high amounts of toxic solanine and chaconine, exceeding by 2-5-fold the recommended limit, and ranging from 2578±86mg/kg to 5063±230mg/kg of dry weight potato flesh. For safety consideration, these decayed potatoes should be systematically set aside. To avoid a net economic loss and encourage the removal of this hazardous food, a recycling process was investigated to generate added-value compounds from the toxic glycoalkaloids. A simple chemo-enzymatic protocol comprising a partial acidic hydrolysis followed by an enzymatic treatment with the β-glycosidase from Periplaneta americana allowed the efficient conversion of α-chaconine to solanidine.

Bioactive Compounds in Potato Tubers: Effects of Farming System, Cooking Method, and Flesh Color

We investigated the effect of cultivation system (conventional or organic), cooking method, and flesh color on the contents of ascorbic acid (AA) and total phenolics (TPs), and on total antioxidant activity (Trolox equivalents, TE) in Solanum tuberosum (potato) tubers. The research material, consisting of 4 potato cultivars, was grown in experimental fields, using organic and conventional systems, at the experimental station in 2012 and 2013. The analysis showed that organically grown potatoes with creamy, light yellow, and yellow flesh had significantly higher TPs than did potatoes grown conventionally. Flesh color and cooking method also affected AA. The greatest losses of AA occurred in yellow-fleshed potatoes grown conventionally and cooked in the microwave; such losses were not observed in potatoes grown organically. A dry cooking method (baking in a microwave) increased the TP contents in potatoes by about 30%, regardless of the flesh color and the production system. TE was significantly higher in organically grown potatoes (raw and cooked in a steamer) than in conventionally grown potatoes. TE and AA contents showed a significant positive correlation, but only in potatoes from the organic system [R² = 0.686]. By contrast, the positive correlation between TE and TPs was observed regardless of the production system. Therefore, we have identified the effects of farming system, cooking method, and flesh color on the contents of bioactive compounds in potato tubers.