Potential applicaton of β-galactosidase in food science and nutrition

β-galactosidase is an enzyme with hydrolytic and transgalactosylation activity. The origin of the enzyme dictates the balance between both activities. Industrially used β-galactosidases are obtained with recombinant production from filamentus funghi Aspergillus sp. and yeasts Kluyveromyces sp. Recently thermostabile β-galactosidases have been subject of many research. The enzyme can be industrially used in free or immobilized form. Immobilization often provides better stability, reusability and lower expenses. Application of β-galactosidase is most common in food processing and nutrition, it is also used in medicine and ecology. Hydrolytic activity of the enzyme has long been used for reducing lactose content in milk, while transgalactosylitic activity is used for synthesis of products such as galactooligosaccharides, lactosucrose and others. The latter have a great potential in food industry for obtaining products with reduced lactose content and increasing of nutritional value by adding dietetic fibers such as galactooligosaccharides. Despite the potential it is vital that reaction mechanisms become better understood and optimization is in place in order to reach the usability of this enzyme at industrial level

Effects of selected essential oils on the growth and production of ochratoxin A by Penicillium verrucosum

Eterična olja origana (Origanum vulgare L.), mete (Mentha piperita L.), janeža (Foeniculum vulgare Mill.), in borovih (Abies alba Mill.) iglic in storžev, ter njihove sestavine timol, karvakrol, mentol in anisaldehid smo testirali kot snovi z protiglivno aktivnostjo proti plesnim vrste Penicillium verrucosum. Najnižje minimalne inhibitorne koncentracije (MICs) smo določili eteričnemu olju origana, ter karvakrolu, timolu, in mentolu. Rast plesni vrste P. verrucosum je bila popolnoma inhibirana po 21 dneh inkubacije v prisotnosti ½ MIC timola (0,0625 mg mL-1), medtem ko so eterično olje origana (½ MIC, ¼ MIC), timol (¼ MIC) in karvakrol (½ MIC, ¼ MIC) inhibirali rast plesni od 8,3 % do 70.8 %. Dodatek mentola v koncentracijah ¼ MIC in ½ MIC (0.1875 mg mL-1 in 0.3750 mg mL-1) pa ni imel inhibitornega vpliva na rast plesni vrste P. verrucosum. Popolno inhibicijo tvorbe ohratoksina A smo določili le v primeru, ko je bila tudi rast teh plesni popolnoma inhibirana (pri ½ MIC timola). Največjo inhibicijo tvorbe ohratoksina A (96,9 %) po 21 dnevih inkubacije smo določili pri ¼ MIC timola (0.0313 mg mL-1). Pospešeno tvorbo ohratoksina A (od 13,9 % do 28,8 %) pa smo določili pri ¼ MIC eteričnega olja origana (0.2930 mg mL-1) in ½ MIC karvakrola (0.1953 mg mL-1). Protiglivni vplivi so bili odvisni od testirane snovi, njene koncentracije ter časa interakcij med protiglivno snovjo in plesnimi vrste P. verrucosum. Rezultati nakazujejo možnosti uporabe eteričnega olja origana v živilih namesto kemijskih konzervansov. Ker pa so živila kompleksna okolja v katerih je potrebno upoštevati več dejavnikov, so potrebne nadaljnje raziskave.Essential oils from oregano (Origanum vulgare L.), mint (Mentha piperita L.), fennel (Foeniculum vulgare Mill.), and pine (Abies alba Mill.) needles and cones, and their active substances thymol, carvacrol, menthol, and anisaldehyde were tested for antifungal activity against Penicillium verrucosum. The lowest minimal inhibitory concentrations (MICs) were achieved for essential oil of oregano, followed by carvacrol, thymol, and menthol. These antifungal components were further investigated, as the main aim of our study was to elucidate the effect of natural antifungals on ochratoxin A production. During 21 days of exposure, the growth of P. verrucosum, and subsequently the production of ochratoxin A, was fully inhibited by thymol at ½ MIC (0.0625 mg mL-1), but menthol at ¼ and ½ MIC (0.1875 and 3750 mg mL-1) showed no growth inhibition. After 21 days of incubation, the greatest inhibitory effect on ochratoxin production (inhibition was 96.9 %) was also achieved with thymol at ¼ MIC (0.0313 mg mL-1). Essential oil of oregano (¼ MIC, 0.2930 μL mL-1) and carvacrol (½ MIC, 0.1953 μL mL-1) stimulate production of ochratoxin A at 13.9 % to 28.8 %, respectively. The observed antifungal effects depended on the agent, the concentration used, and the time of interaction between the agent and P. verrucosum. Our results indicate the possibility of using oregano essential oil as a substitute for artificial preservatives in certain foods, but further research is needed

Genetička, biokemijska, hranjiva i antimikrobna svojstva šipka (Punica granatum L.) uzgojenog u Istri

This study characterises the genetic variability of local pomegranate (Punica granatum L.) germplasm from the Slovenian and Croatian areas of Istria. The bioactive components and antioxidant and antimicrobial properties of ethanol and water extracts of different parts of pomegranate fruit were also determined, along with their preliminary nutritional characterisation. Twenty-six different genotypes identified with microsatellite analysis indicate the great diversity of pomegranate in Istria. The pomegranate fruit ethanol extracts represent rich sources of phenolic compounds (mean value of the mass fraction in exocarp and mesocarp expressed as gallic acid is 23 and 16 mg/g, respectively). The ethanol extracts of pomegranate exocarp and mesocarp showed the greatest antimicrobial activity against Candida albicans, Candida parapsilosis, Rhodotorula mucilaginosa, Exophiala dermatitidis and Staphylococcus aureus, and the same water extracts against S. aureus and Escherichia coli. To the best of our knowledge, this study represents the first report of the characterisation of pomegranate genetic resources from Istria at different levels, including the molecular, chemical, antimicrobial and nutritional properties.U ovom je radu opisana genetička raznolikost germplazme šipka (Punica granatum L.) s područja slovenskog i hrvatskog dijela Istre. U etanolnim i vodenim ekstraktima različitih dijelova ploda šipka pronađeni su bioaktivni spojevi, te su ispitana njihova antioksidacijska i antimikrobna svojstva i preliminarno određena hranjiva svojstva ekstrakata. Dvadeset i šest različitih genotipova utvrđenih analizom mikrosatelita upućuju na veliku raznolikost šipka u Istri. Etanolni ekstrakti ploda šipka predstavljaju bogat izvor fenolnih spojeva (srednja vrijednost masenog udjela, izraženog kao galna kiselina, bila je 23 mg/g u egzokarpu i 16 mg/L u mezokarpu). Etanolni ekstrakti egzokarpa i mezokarpa šipka imali su snažan antimikrobni učinak na sljedeće vrste: Candida albicans, Candida parapsilosis, Rhodotorula mucilaginosa, Exophiala dermatitidis i Staphylococcus aureus, dok su vodeni ekstrakti egzokarpa i mezokarpa uspješno suzbijali rast bakterija S. aureus i Escherichia coli. Prema našim spoznajama, ovo je prva karakterizacija genetičkih izvora šipka iz Istre, koja obuhvaća molekularna, kemijska, antimikrobna i hranjiva svojstva plodova

Encapsulation of Bilberry Extract with Maltodextrin and Gum Arabic by Freeze-Drying: Formulation, Characterisation, and Storage Stability

Anthocyanins are polyphenolic plant pigments associated with antioxidant and health-promoting properties. However, their application in the food industry is limited due to their poor stability. The purpose of this study was to encapsulate anthocyanin-rich bilberry (Vaccinium myrtillus L.) extract by freeze-drying and to investigate the effects of different wall materials and extract contents on the physicochemical and bioactive properties of the obtained encapsulates. Ethanolic bilberry extract was encapsulated with the use of maltodextrin (16.5–19.5 DE) (MD), gum Arabic (GA), and their combination in a 1:1 w/w ratio (MIX). Bilberry solids to wall material ratios were examined at 20:80, 30:70, and 40:60. All encapsulates showed an attractive red colour and low water activity values (aw ≤ 0.3) that indicated a low risk of microbial spoilage. In general, the biggest losses of total phenolic compounds and anthocyanins during three-week storage in the dark and at room temperature (20 ± 2 °C) were detected in the case of encapsulates with a higher content of bilberry extract (MIX30 and MIX40, and GA30 and GA40, respectively). The use of maltodextrin provided the best protection to bilberry anthocyanins during forced storage. Overall, the obtained encapsulates show suitable potential for the development of food products with added nutritional benefits

An Integrated Characterization of Jujube (Ziziphus jujuba Mill.) Grown in the North Adriatic Region

Žižula (Ziziphus jujuba Mill.) ima dobra hortikulturna svojstva, koja uključuju prilagodbu uvjetima suše, abiotskim i biotskim stresovima, te pozitivan utjecaj na zdravlje ljudi. U ovom je istraživanju opisana genska raznolikost germplazme žižule s istarskog poluotoka, te su određeni važni kemijski spojevi, antioksidacijski, antibakterijski i protugljivični učinak ekstrakata plodova žižule te njihova hranjiva svojstva. Rezultati analize gena pokazuju da većina uzoraka s istarskog poluotoka pripada dvjema nedavno introduciranim sortama, \u27Li\u27 i \u27Lang\u27, te najrasprostranjenijoj lokalnoj sorti Domaća žižula\u27. Lokalna sorta ima sitnije plodove od sorata \u27Li\u27 i \u27Lang\u27, s tanjim i mesnatijim mezokarpom. Kemijska je analiza pokazala da su plodovi lokalne sorte vrijedan izvor vlakana ((9,7±0,6) g/100 g), te da su bogati mineralima poput kalija ((829±51) g/ 100 g suhe tvari), kalcija ((1 77±1 1 ) g/ 1 00 g suhe tvari) i fosfora ((129±19) g/ 100 g suhe tvari). Vodeni su ekstrakti imali blagu antibakterijsku aktivnost, dok su etanolni ekstrakti imali veće masene udjele fenolnih spojeva (5,8-8,7 mg/g), izražene kao ekvivalent galne kiseline (GAE), od vodenih ekstrakata, no nisu imali antimikrobnu aktivnost. Osim fenolnih spojeva, i ostali spojevi u plodu žižule mogu imati veću biološku aktivnost. Na osnovi rezultata ovih analiza smatramo da lokalna istarska sorta žižule ima potencijal za uzgoj.Jujube (Ziziphus jujuba Mill.) has favourable horticultural properties including adaptation to arid conditions, abiotic and biotic stresses, as well as positive impact on human health. The present study describes the characterization of genetic diversity of the germplasm of jujube from the Istrian peninsula, the determination of important chemical compounds, antioxidative properties in relation to antibacterial and antifungal activities of jujube fruit extracts, and the determination of nutritional properties of jujube fruit. The results of the genetic analysis showed that most of the samples from the Istrian peninsula belong to two recently introduced varieties, \u27Li\u27 and \u27Lang\u27, and the most widespread local variety \u27Navadna žižola\u27. The local variety has smaller fruit than the ‘Li’ and ‘Lang’ varieties, with thick and fleshy mesocarp. Chemical analysis indicated that fruits of the local variety contained a valuable source of dietary fibre ((9.7±0.6) g/100 g) and were rich in minerals such as (in g/100 g dry mass): potassium (829±51), calcium (177±11) and phosphorus (129±19). Aqueous extracts showed slight antibacterial activity, while ethanol extracts had higher mass fractions of phenolic compounds (expressed as gallic acid equivalents (GAE), 5.8-8.7 mg/g) than the aqueous extracts, but did not show antimicrobial activity. Compounds other than phenolic compounds in jujube fruit may be more biologically active. Based on the results of these analyses, the local Istrian jujube variety is a promising candidate for cultivation potential

Optimization of growth for the hyperthermophilic archaeon Aeropyrum pernix on a small-batch

Abstract: Growth of Aeropyrum pernix, the first reported aerobic neutrophilic hyperthermophilic archaeon, was investigated under different cultivation parameters. Different sources of seawater, pH, and the cultivation methods were tested with the aim to improve the biomass production. A 1-L glass flask fitted with a condenser and air diffuser was used as a bioreactor. The optimum conditions for maximizing A. pernix biomass were obtained when Na 2 S 2 O 3 ·5H 2 O (1 g/L) with added marine broth 2216 at pH 7.0 (20 mmol HEPES buffer/L) was used as a growing medium in a 1-L flask. The biomass production was 0.45 g dry cell mass/L in 40 h under the optimum conditions, which is more than the 0.42 g dry cell mass/L in 60 h previously obtained. Key words: Aeropyrum pernix, hyperthermophilic archaeon, biomass production, simple glass flask based system. Mots clés : Aeropyrum pernix, archéen hyperthermophile, production de biomasse, système simple reposant sur un flacon de verre

Enhanced yield of oleuropein from olive leaves using ultrasound‐assisted extraction

The aim of this study was to optimize the extraction of oleuropein from olive leaves through a systematic study of the effects of different parameters of ultrasound‐assisted extraction (USAE) on the oleuropein yield, in comparison with conventional maceration extraction. A range of operational parameters were investigated for both conventional maceration extraction and USAE: solvent type, olive leaf mass‐to‐solvent volume ratio, and extraction time and temperature. Oleuropein yield was determined using high‐performance liquid chromatography, with total phenolics content also determined. The optimized conditions (water–ethanol, 30:70 [v/v]; leaf‐to‐solvent ratio, 1:5 [w/v]; 2 hr; 25°C) provided ~30% greater oleuropein extraction yield compared to conventional maceration extraction. The total phenolics content obtained using the optimized USAE conditions was greater than reported in other studies. USAE is shown to be an efficient alternative to conventional maceration extraction techniques, as not only can it offer increased oleuropein extraction yield, but it also shows a number of particular advantages, such as the possibility of lower volumes of solvent and lower extraction times, with the extraction carried out at lower temperatures

In vitro comparison of the bioactivities of Japanese and Bohemian knotweed ethanol extracts

Knotweed is a flowering plant that is native to temperate and subtropical regions in the northern hemisphere. We evaluated Japanese (Reynoutria japonica Houtt.) and Bohemian (Fallopia x bohemica) knotweed rhizome and flower ethanol extracts and compared them in terms of their biological activities. The specific polyphenols were identified and quantified using HPLC/DAD, and the antioxidant activity was determined using 2,2-diphenly-1-picrylhydrazyl (DPPH) and cellular antioxidant capacity assays. The anticancer activity was evaluated as the difference between the cytotoxicity to cancer cells compared with control cells. The antimicrobial activity was determined using bacteria and yeast. The antidiabetic activity was tested as the ability of the extracts to inhibit α-amylase. Both rhizome extracts were sources of polyphenols, particularly polydatin and (−)-epicatechinhowever, the cellular assay showed the highest antioxidant capacity in the flower extract of F. bohemica. The PaTu cell line was the least sensitive toward all knotweed extracts. The flower extracts of both species were less toxic than the rhizomes. However, the activity of the tested extracts was not specific for cancer cells, indicating a rather toxic mode of action. Furthermore, all used extracts decreased the α-amylase activity, and the rhizome extracts were more effective than the flower extracts. None of the extracts inhibited bacterial growthhowever, they inhibited yeast growth. The results confirmed that rhizomes of Reynoutria japonica Houtt. could become a new source of bioactive compounds, which could be used for the co-treatment of diabetes and as antifungal agents