Horseradish contains many bioactive compounds with antioxidant activity. The current study aimed to evaluate the effect of various wall materials and their ratios on the physical properties and bioactive-compound retention and stability in microencapsulated horseradish leaf and root juices. Horseradish juice was microencapsulated using maltodextrin, maltodextrin/gum Arabic, soy protein isolate, and starch with three different core-to-wall ratios. The total phenolic, total flavonoid, total flavan-3-ol, and total phenolic-acid contents, as well as antioxidant activity, were determined using spectrophotometric methods, whereas individual phenol profiles were determined by high-performance liquid chromatography (HPLC). Multivariate analysis of variance showed that plant material, wall material, and core-to-wall ratio had a significant effect on the bioactive-compound retention and antioxidant-activity preservation. Microcapsules produced from horseradish leaf juice had a significantly higher content of phenolic compounds and antioxidant activity compared to root-juice microcapsules. However, better retention was observed for microencapsulated horseradish root juice. Maltodextrin and maltodextrin/gum Arabic were the most effective wall materials for the retention of bioactive compounds, while they also had a smaller particle size and better solubility. The horseradish-juice microcapsules possess a high content of rutin. The highest stability of bioactive compounds after storage was found at a core-to-wall ratio of 20:80.

Horseradish (Armoracia rusticana) leaves pomace, which contains high-value bioactive compounds, is the product resulting from pressing horseradish leaves for juice production. The aim of the current research was to investigate the effect of convective, microwave-vacuum and freeze-drying on the content of bioactive compounds in horseradish leaves pomace. Convective hot air-drying was performed at 40, 60 and 80 °C. The total phenolic content (TPC), total flavonoid content (TFC), total flavan-3-ol content, total phenolic acid content, total flavonol content, chlorophylls and total carotenoids, and antioxidant activity were determined by spectrophotometric methods. Individual profiles of phenols and organic acids are estimated by high-performance liquid chromatography (HPLC), but volatile compounds are estimated by gas chromatography (GC). Totally, 14 individual phenolic compounds, 8 organic acids, and 49 volatile compounds were analysed in the studied samples. The main phenolic compound identified in horseradish leaves pomace was rutin (3231 mg/100 g DW), among organic acids—quinic and malic acids, and volatile compounds—allyl isothiocyanate, 3-butenenitrile and benzyl alcohol. In the drying process, the content of some (total flavan-3-ols, total carotenoids content) compounds increased, but others (TPC, total organic acids content) decreased, and it was drying method-dependent. Freeze-drying caused the reduction of TPC by 29%, whereas convective drying by 53–59%. Fresh pomace contains such isothiocyanates as allyl isothiocyanate and butyl isothiocyanate, which were completely lost in the drying process. Freeze-drying allowed the best retention of various phenolic and volatile compounds in horseradish leaves pomace.

Worldwide it is of great interest to find new and safe antioxidants from natural sources. Green leafy vegetables and wild plant leaves are healthy nutrients, containing vitamins, minerals and biological active compounds, therefore these plants provide beneficial health effects due to the presence of antioxidant compounds. It is useful and popular to supplement human diets with fresh or frozen edible plants. It is known that freezing may help to preserve the quality of plants, and is superior to other preservation methods. The aim of research was to compare the phenolic compounds content of fresh and frozen edible wild plants leaves grown in Latvia. The samples were processed using freezing -20 °C and for a comparison fresh samples were analysed. The leaves of stinging nettle (Urtica dioica), common goutweed (Aegopodium podagraria), dandelion (Taraxacum officinale) and chickweed (Stellaria media) were collected in May 2016 in Latvia. In the current research the content of total phenolics was determined in four types of fresh and frozen plant leaves and they can be arranged as follows (starting from plant with less phenolics content as gallic acid equivalent): dandelion

Phenolic compounds are of a considerable interest and have received more and more attention in recent years due to their bioactive functions. These components are known as secondary plant metabolites and also possess antimicrobial, antiviral and anti-inflammatory properties. The popular Latvian herbals – Calendula (Calendula officinalis L.), Lady’s-mantle (Alchemilla vulgaris L.), Yarrow (Achillea millefolium L.), Peppermint (Mentha × piperita L.) and Bellis (Bellis perennis L.) – are widely used for herbal teas. The objective of this study was to determine individual phenolic compounds in herbal infusions using high-performance liquid chromatography. The obtained results showed significant differences (p ˂ 0.05) of the phenolics content in the analysed herbal teas. The total content of the identified 14 phenolic compounds in Yarrow tea was on the average 136.76 ± 0.8 mg 100 g–1, in Peppermint tea 304.38 ± 10.7 mg 100 g–1, in Lady’s-mantle tea 319.53 ± 12.5 mg 100 g–1, in Calendula tea 586.36 ± 17.6 mg 100 g–1, but in Bellis tea it was 802.96 ± 21.3 mg 100 g–1. The dominant phenolic compound in Peppermint, Lady’s-mantle and Yarrow teas was rutin, but chlorogenic acid in Bellis tea. Calendula tea has an abundant quantity of sinapic acid.

Whey contains a lot of lactose, which can be easily hydrolysed by commercial enzymes. The aim of the present study was to identify the optimal parameters for the enzymatic hydrolysis of acid whey permeate and glucose-galactose syrup production. Acid whey permeate was hydrolysed using β-galactosidase preparate (NOLA TM Fit 5500, Chr. Hansen, Denmark) with activity 7200 BLU L -1 . As the enzyme is strongly inhibited at pH below 4.5, sodium bicarbonate was added to neutralize substrate pH till 6.0-6.3. The hydrolysis was carried out at 40 °C 6 hours. pH and monosaccharides concentration were monitored during the process of hydrolysis. The fermented substrate was concentrated in a vacuum evaporator at 40-60 °C, 4-8 kPa. Glucose-galactose syrup was obtained with 65 and 70% of total solids. Lactose and monosaccharides were determined by HPLC. Fermentation time influenced monosaccharides composition and concentration. After 2 hours of fermentation lactose was completely hydrolysed. Continuing fermentation, the amount of glucose was decreased due to formation of novel oligosaccharides. The study results revealed that the optimal time for acid whey permeate hydrolysis was 2 hours. It should be noted that during the process of hydrolysis the pH of the product increased till 6.5 and such changes are related to cellulase and glucoamylase activity incorporated in the enzyme preparate as well as permeate protein residues hydrolysis. With the increase of syrup total solids, galactose concentration was changed due to galacto-oligosaccharides formation. The degree of sweetness is key factor for the durability of lactose hydrolysis and final syrup concentration.