Characterization of Bioactive Compounds in Colored Potato (Solanum Tuberosum L.) Cultivars Grown with Conventional, Organic, and Biodynamic Methods

Studies of the Variability of Biologically Active Compounds and Antioxidant Activity in Organically, Biodynamically, and Naturally Grown and Fermented Fireweed (Chamerion angustifolium (L.) Holub) Leaves

With the growing global demand for organically and biodynamically grown fireweeds, little research is being conducted on them, and little is known about how the different growing systems and the process of solid-phase fermentation changes biologically active substances and antioxidant activity. Our experiment was conducted in 2022 in Jonava district, Safarkos village, Giedres Nacevicienes organic farm (No. SER-T-19-00910, Lithuania, 55°00'22″ N 24°12'22″ E). This study aimed to investigate the influence of various growing systems (natural, organic, and biodynamic) and technological parameters (different duration: 24, 48 and 72 h) of aerobic solid-phase fermentation on the change of flavonoids, phenolic acids, tannins, carotenoids, chlorophylls, and antioxidant activity. High-performance liquid chromatography (HPLC) for polyphenols, carotenoids, and chlorophylls as well as the spectrophotometric method for antioxidant activity determinations were used. The results of the study showed that different growing systems (natural, organic, and biodynamic) and solid-phase fermentation had a significant effect on the quantitative composition of biologically active substances in the leaves of the fireweeds. According to these data, it would be possible to recommend fermented fireweed leaves grown organically as a source of polyphenols (especially: phenolic acids and flavonoids), leaves grown biodynamically as a source of carotenoids (exceptionally: lutein and beta-carotene) and chlorophyll, and leaves grown naturally for better antioxidant activity.

Changes in Pomological and Physical Parameters in Rosehips during Ripening

Rosehips of various Rosa spp. are well known for having human health-promoting compounds like mineral nutrients, vitamins, fatty acids, and phenolic compounds. However, little is known about rosehip characteristics which describe the fruit quality and may indicate appropriate harvest times. Our study evaluated the pomological (width, length, and weight of fruits, flesh weight, and seed weight), texture, and CIE colour parameters (L*, a*, and b*), chroma (C), and hue angle (h°) of rosehip fruits of Rosa canina, Rosa rugosa, and genotypes of Rosa rugosa 'Rubra' and 'Alba', harvested at five ripening stages (I-V). The main results revealed that genotype and ripening stage significantly affected parameters. The significantly longest (R. canina) and widest fruits (R. Rugosa) were measured at ripening stage V. Genotypes of R. rugosa 'Rubra' and 'Alba' had significantly higher fruit and flesh weights at ripening stage V. Rosehips of all investigated genotypes expressed darkness (lower L*) during ripening, and had the highest hue angle h° values at ripening stage I while the lowest was at stage V. The significantly lowest skin elasticity of rosehips was found at stage V. However, R. canina was distinguished by the highest fruit skin elasticity and strength. As our results show, the desired pomological, colour, and texture features of various species and cultivars rosehips can be optimised according to the harvest time.

Phenolic Acid Content and Antioxidant Properties of Edible Potato (Solanum tuberosum L.) with Various Tuber Flesh Colours

The aim of the paper was to evaluate the phenolic acid content and antioxidant properties in potato cultivars with coloured flesh and bright flesh. The study material included eight cultivars of edible potato grown in a temperate climate in Poland. Five cultivars were potato tubers with coloured flesh: "Rote Emma", "Blue Salad", "Vitelotte", "Red Emmalie", and "Blue Congo"; and three were potato tubers with bright flesh: "Bella Rosa", "Lord", and "Tajfun". In all potato samples under study, four phenolic acids were identified: chlorogenic acid, gallic acid, p-coumaric acid, and caffeic acid. The predominant acid was chlorogenic acid, the levels of which ranged from 62.95 mg·100 g^-1 FM to 126.77 mg·100 g^-1 FM. The total concentration of the identified phenolic acids was diverse and depended on the genotype of the cultivar and the tuber flesh colour, with coloured-fleshed potatoes having higher phenolic acid contents in comparison to bright-fleshed potato cultivars. The average concentration of phenolic acids in the samples was 89.19 mg∙100 g^-1 FM, and the average concentrations of the individual phenolic acids identified were as follows: chlorogenic acid (86.19 mg∙100 g^-1 FM), gallic acid (1.18 mg∙100 g^-1 FM), p-coumaric acid (0.64 mg∙100 g^-1 FM), and caffeic acid (1.18 mg∙100 g^-1 FM). In addition, three groups of anthocyanins were identified: pelargonidin-3,5-di-O-glucoside, peonidin-3,5-di-O-glucoside, and petunidin-3,5-di-O-glucoside. Anthocyanins were not found in the "Lord" or "Tajfun" varieties characterised by white tuber flesh. The predominant pigment was petunidin-3,5-di-O-glucoside, with an average content of 23.15 mg∙100 g^-1 FM, and the highest value was observed in the "Vitelotte" variety (51.27 mg∙100 g^-1 FM). The antioxidant activity of the flesh of the potatoes under study was diverse depending on flesh colour. The FRAP (Ferric Reducing Antioxidant Power) assay indicated higher antioxidant activity of coloured-fleshed potato cultivars. The highest concentration was identified in the "Vitelotte" cultivar flesh and was 114% higher than in the "Lord" cultivar. Similar dependencies were found in the case of the DPPH (2,2-diphenyl-1-picrylhydrazyl) assay; however, in this case, the "Vitelotte" cultivar flesh demonstrated nearly 6.4 times higher antioxidant activity than the "Lord" cultivar. Summarizing our own research, we can conclude that potato varieties with coloured flesh are characterised by a higher content of biologically active substances, including phenolic acids, and antioxidant properties compared to potato tubers with bright flesh.

Profile of Selected Secondary Metabolites and Antioxidant Activity of Valerian and Lovage Grown in Organic and Low-Input Conventional System

In the present study, the roots of valerian (Valeriana officinalis L.) and lovage (Levisticum officinale Koch.) from the organic and low-input conventional cultivation systems were subjected to the analysis of selected groups of phenolic compounds (phenolic acids, flavonoids) and antioxidant activity. Plants were grown in two consecutive vegetation seasons in the experimental plots located in western Poland. Phenolic acids and flavonoids were determined by high performance liquid chromatography (HPLC/UV–Vis), while the antioxidant activity of the samples was measured with the use of DPPH radical scavenging activity assay. The concentrations of phenolic acids (sum) and flavonoids (sum) were found to be higher in the conventional lovage roots, as compared to the organically grown lovage roots, while in the case of valerian, no significant effects of the cultivation system on the levels of the sums of these analyzed compounds were found. Furthermore, no significant effect of the cultivation system on the antioxidant activity of herbs was observed. Additional efforts could be invested in enhancing the potential of organic medicinal plants to consistently present the expected high concentrations of health-promoting antioxidants, which could be effectively brought through their post-harvest handling, storage and processing, and thus meet consumers’ expectations at the stage when they reach the market.

The Physico-Chemical and Sensory Characteristics of Coloured-Flesh Potato Chips: Influence of Cultivar, Slice Thickness and Frying Temperature

Coloured potato chips, due to a higher concentration of bioactive compounds, may be healthier compared to traditional chips. This study examined the effect of cultivar and different slice thicknesses and frying temperatures on the physico-chemical and sensory characteristics of coloured potato chips. Potatoes chips were prepared from three coloured potato cultivars. Frying experiments were conducted at 160 and 180 °C using potato slices with thicknesses of 1.00 and 2.00 mm. The quality of the raw potatoes tubers and chips were estimated. A principal component analysis was applied to describe the differences in the physico-chemical characteristics between the potato chip samples processed with different conditions. The results showed that, significantly (p < 0.05), the highest amounts of total phenolic content, total anthocyanins, dry matter and starch were accumulated in raw tubers of potato cv. Blaue Anneliese. The highest amount of total phenolic content and anthocyanins was found in 1 mm chips of cv. Blaue Anneliese fried at 160 °C. An increased frying temperature significantly (p < 0.05) decreased the content of these compounds. The amount of fat in the chips was higher when they were fried at 160 °C than at 180 °C. Chips processed from potatoes cvs. Blaue Anneliese and Rosemarie showed a typical colour as a raw material. The hardness of the chips significantly (p < 0.05) increased with an increase in slice thickness. The flavour, odour and colour of the 1 mm chips of cv. Blaue Anneliese fried at 180 °C gained the highest rating.

Metabolomic and Biochemical Analysis of Two Potato (Solanum tuberosum L.) Cultivars Exposed to In Vitro Osmotic and Salt Stresses

Globally, many crop production areas are threatened by drought and salinity. Potato (Solanum tuberosum L.) is susceptible to these challenging environmental conditions. In this study, an in vitro approach was employed to compare the tolerance of potato cultivars ‘BARI-401’ (red skin) and ‘Spunta’ (yellow skin). To simulate ionic and osmotic stress, MS media was supplemented with lithium chloride (LiCl 20 mM) and mannitol (150 mM). GC-MS and spectrophotometry techniques were used to determine metabolite accumulation. Other biochemical properties, such as total phenols concentration (TPC), total flavonoids concentration (TFC), antioxidant capacity (DPPH free radical scavenging capacity), polyphenol oxidase (PPO), and peroxidase (POD) activities, were also measured. The two cultivars respond differently to ionic and osmotic stress treatments, with Spunta accumulating more defensive metabolites in response, indicating a higher level of tolerance. While further investigation of the physiological and biochemical responses of these varieties to drought and salinity is required, the approach taken in this paper provides useful information prior to open field evaluation.