Aleksandra Vojvodić

Comparative evaluation of CO2 drying as an alternative drying technique of basil (Ocimum basilicum L.) — The effect on bioactive and sensory properties

In this study the potential of employing CO2 drying as an alternative to conventional drying techniques of basil was evaluated, with the aim of preservation of native bioactive and sensory properties of basil. For that purpose, optimal CO2 processing conditions were established and compared to air-dried and freeze dried basil samples. The contents of bioactive compounds (polyphenols, chlorophylls, ascorbic acid) and antioxidant capacity were determined spectrophotometrically and using high performance liquid chromatography (HPLC-PDA) analysis. Color analysis and essential oil content were also determined, while consumer evaluation of sensory properties was conducted using hedonic scale preference analysis. According to the obtained results, freeze drying was recognized as the most suitable technique for preservation of color, essential oil content, bioactive compounds and antioxidant capacity of basil. The essential oil content of basil ranged from 0.21 to 0.96%, and decreased upon prolongation of CO2 drying time. Among 4 identified phenolic acids (rosmarinic, chicoric, caftaric and caffeic), rosmarinic acid was the most abundant in all samples. Longer CO2 drying duration (4h) also exhibited the most detrimental effect on the polyphenolic compound content and antioxidant capacity of basil. The taste and appearance of CO2 dried basil were scored higher in comparison to air-dried basil, but further optimization of CO2 drying is needed to improve its aroma properties. Based on the obtained results, employing shorter CO2 drying time (2, 3h) and pressures of 80-100bar at 40°C might be a good alternative to freeze drying of basil.

Compositional evaluation of selected agro-industrial wastes as valuable sources for the recovery of complex carbohydrates

Re-utilization of various agro-industrial wastes is of growing importance from many aspects. Considering the variety and complexity of such materials, compositional data and compliant methodology is still undergoing many updates and improvements. Present study evaluated sugar beet pulp (SBP), walnut shell (WS), cocoa bean husk (CBH), onion peel (OP) and pea pods (PP) as potentially valuable materials for carbohydrate recovery. Macrocomponent analyses revealed carbohydrate fraction as the most abundant, dominating in dietary fibres. Upon complete acid hydrolysis of sample alcohol insoluble residues, developed procedures of high performance thin-layer chromatography (HPTLC) and high performance liquid chromatography (HPLC) coupled with 3-methyl-1-phenyl-2-pyrazolin-5-one pre-column derivatization (PMP-derivatization) were used for carbohydrate monomeric composition determination. HPTLC exhibited good qualitative features useful for multi-sample rapid analysis, while HPLC superior separation and quantification characteristics. Distinctive monomeric patterns were obtained among samples. OP, SBP and CBH, due to the high galacturonic acid content (20.81%, 13.96% and 6.90% dry matter basis, respectively), may be regarded as pectin sources, while WS and PP as materials abundant in xylan-rich hemicellulose (total xylan content 15.53%, 9.63% dry matter basis, respectively). Present study provides new and valuable compositional data for different plant residual materials and a reference for the application of established methodology.

Consumer acceptability of liquorice root (Glycyrrhiza glabra L.) as an alternative sweetener and correlation with its bioactive content and biological activity.

Abstract Consumer acceptability and sensory properties of liquorice root (Glycyrrhiza glabra L.) were evaluated. Quantitation of total polyphenolics and glycyrrhizic acid (GA), as well as the antioxidant capacity of liquorice extracts, was conducted and their biological effects (cytotoxic, antioxidative/pro-oxidative activity, lipid peroxidation on human laryngeal carcinoma cell line) compared to the ones of their predominant bioactive compound – GA. Conducted consumer survey revealed poor familiarity with liquorice (12.37% of correspondents), but willingness towards its use as an alternative sweetener (77.32% of consumers). Polyphenolic content of evaluated extracts ranged from 1018.18 to 1277.27 mg gallic acid equivalents (GAE)/l while GA content varied between 2179.53 and 2944.13 mg/l. The most pronounced cytotoxic effect (60%) and lipid peroxidation were exerted by treatment with the highest applied extract concentrations (10 mg/ml). Pure GA exhibited cytotoxic and pro-oxidative effects at concentrations of 0.12–0.6 mg/ml. Due to high GA content, coupled with its pronounced cytotoxic activity, the intake of liquorice root should be limited.

Formulating blackberry leaf mixtures for preparation of infusions with plant derived sources of sweeteners

Herbal mixtures composed of blackberry leaf and natural sweeteners (dried apples, prunes, figs, raisins, apricots, carrot and sweet potato, stevia leaves and liquorice root) were developed. Their nutritive and bioactive profile, biological activity and sensory properties were determined. Formulated mixtures exhibited lower total polyphenol content (259.09-350.00 mg GAE/L) when compared to plain blackberry leaf, but contained higher content of chlorogenic, ferulic, p-coumaric, rosmarinic acids and quercetin, as well as some macroelements (Ca, K, Mg) and microelements (Ba, Na). Stevia addition to formulated mixtures ensured higher polyphenolic content. Dried carrot exhibited the highest (0.988 g/g) and liquorice the lowest (0.087 g/g) content of total sugars but it contributed to the sweetness with 574.48 mg/L of glycyrrhizic acid derivatives. Plain blackberry leaf extract exhibited cytotoxic and antioxidative activity on human colon cancer cells. Formulated mixtures exhibited improved flavour profile and balanced sweetness in relation to plain blackberry leaf infusion.

Application of whey protein isolates and zein for the formulation of alginate-based delivery systems encapsulating Ganoderma lucidum polyphenols

Due to the rich phytochemical composition of the medicinal mushroom Ganoderma lucidum, especially its ß-glucan-based polysaccharides and triterpenes, but polyphenols, amino acids, and proteins as well, Ganoderma is often used in various nutraceutical and functional food products. Lately these products have been formulated with microencapsulated forms of active compounds in order to prevent their degradation after oral consumption and under processing conditions. The aim of this study was to characterize and encapsulate polyphenols from the aqueous extract of Ganoderma, using ionic gelation of alginate (A) and its combination with whey protein isolates (WPI) and zein (Z). The obtained hydrogel beads were scanned for physico-chemical and morphological properties, encapsulation efficiency of polyphenols, and their release kinetics in simulated gastrointestinal fluids. The addition of WPI to the alginate resulted in the reduction of the particle size and the spherical shape of the beads, while beads formulated with zein were characterized as larger, with irregular morphology. Encapsulation efficiency of total polyphenols has been determined as follows: 76.91% (A-WPI) < 83.91% (A) < 85.42% (A-Z). The most extended release of polyphenols in simulated gastrointestinal fluids has been achieved by employing WPI in the alginate delivery system. The implementation of additional coatings resulted in the enhanced properties of plain alginate carrier, where alginate-based hydrogels immobilizing Ganoderma polyphenols proved to be potential functional ingredients.

Effects of Varieties and Growing Conditions on Antioxidant Capacity of Coffee

Abstract Chemical composition of green coffee beans principally determines the quality and preference of Arabica ( Coffea arabica species) over Robusta ( Coffea canephora species) coffees. In the present paper a summarized insight on the influence of different factors on the contents of several compounds in green coffee, often used as species and cultivar discriminators and known as powerful antioxidants, is given. The genotype was found to be the most influencing factor, promoting Robusta green coffees as more abundant in chlorogenic acids (the most studied green coffee antioxidants) and caffeine. However, when assessing and comparing the antioxidant quality of green coffees, besides genetics, a defined set of environmental descriptors is needed. Geographical origin, with all environmental attributes of the growing area, together with growing practice, correlate both positively and negatively with the changes in antioxidant composition. Additionally, the impact of primary processing and storage can not be excluded.

Novel Approach for the Development of Functional Goat Milk-based Beverages Using Medicinal Plant Extracts in Combination with High Intensity Ultrasound Treatment

Regardless of its highly valuable nutritive composition, goats milk is less preferred by consumers due to its specific sensory characteristics that are very often regarded as undesirable. On the other hand, traditional medicinal plants from Lamiaceae family, due to their rich bioactive composition, especially polyphenols, and desirable aroma profile, can be used to enhance and improve bioactive and sensory properties of food. In the present study nutritively valuable beverages were produced by enrichment of goats milk with medicinal plant extracts derived from the Lamiaceae family and stabilized by homogenization with high intensity ultrasound treatment. The impact of plant species (lemon balm, mint, lavender, rosemary and sage) and ultrasound treatment duration (5 or 10 min) on the physicochemical, bioactive and sensory characteristics of enriched beverages was evaluated. The addition of plant extracts to goats milk significantly increased the concentration of bioactive components (rosmarinic acid, hydroxycinnamic acid derivatives and luteolin derivatives), in dependence of the added plant extract. The prolongation of the ultrasound homogenization markedly decreased the fat globule size and thus beneficially affected the product stability. Apart from the achieved bioactive enrichment and stability, the developed beverages exhibited significantly improved sensory properties in comparison to plain goats milk, with the highest overall acceptability determined for samples enriched with mint and rosemary.