Basic Chemical Composition, Antioxidant Activity and Selected Polyphenolic Compounds Profile in Garlic Leaves and Bulbs Collected at Various Stages of Development

Abstract

Garlic is commonly used as vegetable or spice and as a herb in folklore as well as traditional medicine in many countries. The current study aimed to compare the chemical composition, antioxidant activity, and the content of selected polyphenolic compounds in cloves as well as leaves of winter garlic plants of the Harnaś and Ornak cultivars, which are of Polish origin. Garlic was grown from cloves for three years (2018–2020) in the experimental field of the University of Agriculture in Krakow, Poland. The research material was harvested on three dates: May; June, unripe garlic plants; and in July, the plant at full maturity. The content of vitamin C in the fresh material was determined. The proximate analysis was determined in the freeze-dried plants of garlic, and the total carbohydrate content was calculated. The antioxidant activity and the content of selected polyphenolic compounds were also determined. Garlic cloves showed a higher content of dry matter, and total carbohydrates than the leaves of garlic plants. On the other hand, in the leaves, a significantly higher content of protein, total fat and ash were observed. Additionally, garlic leaves were characterised by a higher content of vitamin C, total polyphenols, and a higher antioxidant activity than garlic cloves. The leaves of young garlic plants from the May harvest were distinguished by a higher content of these compounds. The dominant phenolic compounds were catechin and epicatechin. The leaves of young plants can be a valuable source of bioactive substances, especially in early spring.

Analytical Assessment of the Antioxidant Properties of the Coneflower (Echinacea purpurea L. Moench) Grown with Various Mulch Materials

“…In freeze-dried samples, the concentration of nitrogen was measured in accordance to the Kjeldahl method (AOAC no. 978.04) [ 41 ] as was previously described [ 42 ]. The percentage of total nitrogen was calculated following the formula N = (V × M × 14.007 × 100)/m, where N—total nitrogen content in g/100 g D.M.…”

“…About 0.5 g of the ground plant material was weighed and mixed with an 80 cm 3 solution of 70% methanol acidified with 0.1% of formic acid ( v / v ; POCh Giwice, Poland) and then placed in a shaker at room temperature for 2 h and protected from light. The mixture was centrifuged for 15 min (402× g , room temperature), and the supernatant was moved into a plastic container and stored at −22 °C [ 42 ].…”

The Identification of Polyphenolic Compounds and the Determination of Antioxidant Activity in Extracts and Infusions of Peppermint, Lemon Balm and Lavender

“…Peppermint herb, lemon balm and lavender were cleaned and dried after the harvesting. Proximate analysis of herbs was carried out based on AOAC methods [21], as was previously reported [22]. Dry mass (DM) in fresh samples was measured based on the AOAC methods [22] in the laboratory oven (Memmert GmbK, Schwabach, Germany).…”

“…Proximate analysis of herbs was carried out based on AOAC methods [21], as was previously reported [22]. Dry mass (DM) in fresh samples was measured based on the AOAC methods [22] in the laboratory oven (Memmert GmbK, Schwabach, Germany). Part of herbs were dried by freeze-drying in a lyophilizer (Christ Alpha 1-4, Gefriertrocknungsanlangen, Germany), and dried samples were used for the proximate analysis.…”

“…Next, the samples were distilled and titrated. The protein content was calculated with formula reported previously with the conversion factor of 6.25 [22]. The crude fat content was measured in plant material (about 1 g of sample) in accordance with the Soxhlet method (AOAC no.…”