Promjene u udjelu fenolnih spojeva i antioksidacijskoj aktivnosti cvjetnog i bagremovog meda tijekom skladištenja

Total flavonoid and total phenolic content were studied in acacia and multifloral honey for 12 months in 6-month intervals. DPPH (1,1-diphenyl-2-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) methods were used to determine total antioxidant activity in honey samples during the same period of time. Samples were stored in transparent glass containers at room temperature, on shelves exposed to natural light during daytime and in the dark during nighttime. Two types of honey from four different regions in Varaždin county, Croatia, were investigated: monofloral – acacia (Robinia pseudoacacia L.) and multifloral. Of the total of 40 samples, there were 20 of each type of honey (5 from each region). The goal of this study is primarily to demonstrate the changes in the antioxidant activity of the two investigated types of honey during one year of storage, and not to make comparisons between them. According to the obtained data, the rate of decrease in the content of total flavonoids and phenolics was determined and changes in the antioxidant activity in honey samples were measured. After one year of storage, total phenolic content decreased by 91.8 % in acacia honey, and by 88.6 % in multifloral honey. Total flavonoid content also decreased in both types of honey, by 45.6 % in acacia honey and by 43.8 % in multifloral honey. During the same period, an increase from 12.20 to 16.73 mg/mL (i.e. by 37.1 %) was recorded in the IC50 values in multifloral honey, while in acacia honey this increase was from 44.64 to 407.01 mg/mL (i.e. by 811.7 %). Decrease in the antioxidant activity measured by FRAP method was also bigger in acacia honey than in multifloral honey (by 428.0 and 72.5 %, respectively), which corresponds well with the results obtained by DPPH method. Simple correlations were made to determine how each of the investigated parameters affects the others. The analysis of variance was used in order to determine the influence of the region, honey type and storage time on different parameters of antioxidant activity as well as on the total phenolic and total flavonoid content in honey samples.U ovom je radu određivan udjel ukupnih flavonoida i fenolnih spojeva u cvjetnom i bagremovom medu tijekom 12 mjeseci u intervalima od 6 mjeseci. Za određivanje antioksidacijske aktivnosti u uzorcima meda korištene su DPPH i FRAP metode. Uzorci su skladišteni na policama u prozirnim staklenim posudicama pri sobnoj temperaturi, izloženi prirodnom dnevnom svjetlu tijekom dana, te mraku tijekom noći. Ispitane su dvije vrste meda: monoflorni bagremov (Robinia pseudoacacia L.) i multiflorni cvjetni med, podrijetlom iz četiri različite regije Varaždinske županije u Hrvatskoj. Ukupni je broj istraživanih uzoraka bio 40, od čega po 20 od svake vrste meda (po pet uzoraka sa četiri lokacije). Svrha je ovog istraživanja bila (bez usporedbe) odrediti promjene u antioksidacijskoj aktivnosti dvije ispitane vrste meda tijekom jednogodišnjeg skladištenja. Određena je stopa smanjenja udjela ukupnih fenola i flavonoida, a praćene su i promjene antioksidacijske aktivnosti. Nakon jednogodišnjeg skladištenja, udjel se ukupnih fenola u medu bagrema smanjio za 91,8 %, a u cvjetnom medu za 88,6 %. Udjel se ukupnih flavonoida također smanjio u obje vrste meda, i to za 45,6 % u bagremovom i 43,8 % u cvjetnom medu. Tijekom istog vremenskog perioda zabilježeno je povećanje IC50 vrijednosti u cvjetnom medu sa 12,20 na 16,73 mg/mL (tj. za 37,1 %), dok su se te vrijednosti u medu bagrema povećale sa 44,64 na 407,01 mg/mL (tj. za 811,7 %). Smanjenje je antioksidacijske aktivnosti, određeno FRAP metodom, također bilo veće u bagremovom (za 428,0 %) od onog u cvjetnom medu (za 72,5 %), što potvrđuju i rezultati dobiveni DPPH analizom. Napravljene su jednostavne korelacije za određivanje utjecaja svakog od ispitivanih parametara. Analizom varijance ispitan je utjecaj lokacije, vrste meda i vremena skladištenja na antioksidacijsku aktivnost, te udjel ukupnih fenola i flavonoida u medu

Volatile Profile, Antioxidant Capacity and Phenolic Content of Istrian Garlic Ecotypes

Garlic (Allium sativum L.) is among the most important vegetable crops used in diet because of its sensory properties and positive health effects. Local producers in Istria (Croatia) have preserved old garlic ecotypes primarily for domestic consumption. Such ecotypes are adapted to specific agro-ecological conditions of Istria and their biochemical properties have not been investigated yet. The aim of this study is to determine the diversity of Istrian garlic ecotypes based on their biochemical profile for further selection of ecotypes with higher biological value in breeding programs. Garlic bulbs were collected from nine locations in Istria and analyzed after two months by chromatographic and spectrometric techniques. Volatiles diallyl sulfide, methyl allyl disulfide, diallyl disulfide, methyl allyl trisulfide, and diallyltrisulfide showed less variability among ecotypes, while total phenolics ranged from 28.5 to 69.5 mg gallic acid equivalents/100 g fresh weight. Two ecotypes and a cultivar abundant in phenolics also showed high antioxidant capacity measured by FRAP or DPPH assays. Several ecotypes stood out with higher dry matter content indicating their potential for longer storage. It was assumed that the determined variability in composition could be partly attributed to different genotypes and growing conditions. This research can contribute to the preservation of garlic biodiversity in Istria as well as to the establishment of a garlic breeding program

Aroma profile and sensory properties of ultrasound-treated apple juice and nectar

Ultrasonication is a nonthermal food processing method that is used in several applications (extraction, treatment before drying, freezing, inactivation of microorganisms, etc.) in ultrasound processing. The objective of this study is to investigate the effect of high power ultrasound and pasteurisation on the aroma profile and sensory properties of apple juice and nectar. Samples were treated according to the experimental design, with high power sonicator at ultrasound frequency of 20 kHz under various conditions (treatment time: 3, 6 and 9 min, sample temperature: 20, 40 and 60 °C, and amplitude: 60, 90 and 120 μm). The aromatic profiles of juices showed that, compared to the untreated samples of juices and nectars, ultrasonic treatment led to the formation of new compounds (which were not present in the untreated samples) or to the disappearance of compounds that were found in the untreated samples. Samples treated at the highest amplitude (120 μm) were used for evaluation and comparison with untreated and pasteurised samples using electronic tongue study. Principal component analysis confirmed the results of electronic tongue study, which showed that the ultrasound-treated and pasteurised juices had different scores compared to the untreated samples

Aromatski profil i senzorska svojstva jabučnog soka i nektara tretiranih ultrazvukom

Ultrasonication is a nonthermal food processing method that is used in several applications (extraction, treatment before drying, freezing, inactivation of microorganisms, etc.) in ultrasound processing. The objective of this study is to investigate the effect of high power ultrasound and pasteurisation on the aroma profile and sensory properties of apple juice and nectar. Samples were treated according to the experimental design, with high power sonicator at ultrasound frequency of 20 kHz under various conditions (treatment time: 3, 6 and 9 min, sample temperature: 20, 40 and 60 °C, and amplitude: 60, 90 and 120 μm). The aromatic profiles of juices showed that, compared to the untreated samples of juices and nectars, ultrasonic treatment led to the formation of new compounds (which were not present in the untreated samples) or to the disappearance of compounds that were found in the untreated samples. Samples treated at the highest amplitude (120 μm) were used for evaluation and comparison with untreated and pasteurised samples using electronic tongue study. Principal component analysis confirmed the results of electronic tongue study, which showed that the ultrasound-treated and pasteurised juices had different scores compared to the untreated samples.Ultrazvuk se može primijeniti kao netermička metoda za ekstrakciju sastojaka, obradu hrane prije sušenja, zamrzavanje, inaktivaciju mikroorganizama i sl. Svrha je ovoga rada bila istražiti utjecaj ultrazvuka velike snage, te postupka pasterizacije na aromatski profil i senzorska svojstva jabučnog soka i nektara. Uzorci su obrađeni ultrazvukom velike snage i niske frekvencije od 20 kHz pri različitim uvjetima (vrijeme tretmana: 3, 6 i 9 min; temperatura: 20, 40 i 60 °C i amplituda: 60, 90 i 120 μm). Iz aromatskog se profila jabučnog soka i nektara može zaključiti da je nakon obrade ultrazvukom došlo do nastanka novih spojeva, a istodobno i do razgradnje nekih spojeva koji su pronađeni u netretiranim uzorcima. Uzorci izloženi ultrazvučnim valovima najveće amplitude (120 μm) uspoređeni su s netretiranim i pasteriziranim uzorcima pomoću elektroničkog jezika. Analizom osnovnih komponenata (engl. principal component analysis - PCA) utvrđeno je da uzorci obrađeni ultrazvukom i pasterizirani sokovi imaju drukčije vrijednosti od netretiranih sokova, što je potvrđeno i senzorskom analizom

Composted sewage sludge influences the microbiome and persistence of human pathogens in soil

Composted sewage sludge (CSS) gained attention as a potential fertilizer in agriculture. Application of CSS increases soil microbial activity and microbial biomass, however, it can also lead to increased chemical and microbiological risks. In this study, we performed microcosm experiments to assess how CSS reshapes the microbial community of diluvial sand (DS) soil. Further, we assessed the potential of CSS to increase the persistence of human pathogens in DS soil and the colonization of Chinese cabbage (Brassica rapa L. subsp. pekinensis (Lour.) Hanelt). The results revealed that CSS substantially altered the prokaryotic community composition. Moreover, addition of CSS increased the persistence of Salmonella enterica serovar Typhimurium strain 14028s and S. enterica serovar Senftenberg in DS soil. However, the enhanced persistence in soil had no impact on the colonization rate of B. rapa grown on soil inoculated with Salmonella. We detected Salmonella in leaves of 1.9% to 3.6% of plants. Addition of CSS had no impact on the plant colonization rate. The use of sewage sludge composts is an interesting option. However, safety measures should be applied in order to avoid contamination of crop plants by human pathogens

Ocjena mlijeka i mliječnih proizvoda elektronskim jezikom

The concept of electronic tongue or taste sensor has been developed rapidly in the last decade due to their large potential in food quality control. The electronic tongue is based on electrochemical sensors combined with multivariate data analysis. The aim of this study was to evaluate the discriminating ability of the electronic tongue for the recognition of different milk and yoghurt samples from different producers and various dairy products from one producer. The results were evaluated by multivariate data analysis - Principal components analysis. The electronic tongue α-ASTREE (Alpha M.O.S) has successfully distinguished five brands of milk purchased on the Croatian market, five brands of yoghurt also purchased on Croatian market and differentiated among various products from one dairy producer.Elektronski jezik ili senzor okusa prilično je dobro razvijen u posljednjih desetak godina, zahvaljujući njegovu velikom potencijalu u kontroli kvalitete prehrambenih proizvoda. Temeljen je na elektrokemijskim senzorima u kombinaciji s multivarijantnim analizama podataka. Cilj ovog rada bio je pomoću elektronskog jezika raspoznati različite uzorke mlijeka i jogurta različitih proizvođača te različite mliječne proizvode jednog proizvođača. Rezultati su izvedeni iz prikaza dobivenih statističkom metodom analize glavnih komponenata. Pomoću elektronskog jezika α-ASTREE (Alpha M.O.S) uspješno su prikazane razlike između pet uzoraka mlijeka različitih proizvođača kupljenih na hrvatskom tržištu, pet uzoraka jogurta različitih proizvođača kupljenih također na hrvatskom tržištu, te između različitih mliječnih proizvoda jednog proizvođača

Odgovor industrijske rajčice na primjenu arbuskularnih mikoriznih gljiva u uvjetima konvencionalne proizvodnje

The potential effect of pre-inoculation of processing tomato (Solanum lycopersicum L.) plants with arbuscular mycorrhizal fungi (AMF) on yield and fruit properties was investigated in conventional production. Tomato seeds were sown in seedling trays filled with a substrate non-inoculated (AMF-) or inoculated (AMF+) by selected mycorrhizal strains. Seedlings were transplanted in Terra rossa soil and grown in conditions with mineral fertilization and irrigation. Tomato fruits were sampled at harvest. Tomato plants under both treatments had high levels of mycorrhizal colonization, due to applied inoculum (AMF+) or indigenous (AMF-) inoculum present in the soil. Applied AMF+ treatment increased P and decreased K content in tomato fruits. Content of trace elements such as As and V significantly increased, while Pb content significantly decreased in the fruits of AMF+ when compared to the AMF- treatment. No significant effect of AMF+ treatment was observed on yield, fruit quality (soluble solids, pH, total acidity, fruit firmness), lycopene and antioxidant activity of tomato fruits. The overall results suggest that processing tomato is highly susceptible to the indigenous AMF, while seedlings inoculation with selected AMF improves only total phenolic and P fruit content. This means that AMF have a potential application in commercial processing tomato production, however a targeted adaptation of management decissions is required for more extensive results.Potencijalni utjecaj inokulacije presadnica industrijske rajčice (Solanum lycopersicum L.) selekcioniranim arbuskularnim mikoriznim gljivama (AMF), na prinos i svojstva ploda, istražen je u konvencionalnoj proizvodnji. Sjeme rajčice posijano je u polistirenske kontejnere s neinokuliranim (AMF-) ili mikorizama inokuliranim (AMF+) supstratom. Presadnice su posađene u crvenicu, u proizvodnim uvjetima s mineralnom gnojidbom i navodnjavanjem. Uzorkovanje plodova industrijske rajčice provedeno je u berbi. Kod oba tretmana utvrđen je visoki postotak kolonizacije selekcioniranim mikorizama (AMF+) i nativnim vrstama (AMF-) prisutnim u tlu. Plodovi rajčice s AMF+ biljaka imali su veći sadržaj P i manji sadržaj K u odnosu na AMF- tretman. Sadržaj As i V bio je signifikantno veći, dok je sadržaj Pb bio signifikantno manji u AMF+ u usporedbi s AMF- tretmanom. Signifikantan učinak tretmana AMF+ na prinos, kvalitetu ploda (suha tvar, pH, ukupna kiselost, čvrstoća ploda), likopen i antioksidacijsku aktivnost je izostao. Temeljem dobivenih rezultata možemo zaključiti da je industrijska rajčica podložna nativnim AMF, dok je ciljana inokulacija presadnica AMF značajno povećala ukupni sadržaj fenola i P. Dobiveni rezultati ukazuju na potencijalnu primjenu AMF u komercijalnoj proizvodnji industrijske rajčice, međutim prethodna prilagodba uzgojnih uvjeta je neophodna za postizanje značajnijih rezultata

Aromatski profil i senzorska svojstva jabučnog soka i nektara tretiranih ultrazvukom

Ultrasonication is a nonthermal food processing method that is used in several applications (extraction, treatment before drying, freezing, inactivation of microorganisms, etc.) in ultrasound processing. The objective of this study is to investigate the effect of high power ultrasound and pasteurisation on the aroma profile and sensory properties of apple juice and nectar. Samples were treated according to the experimental design, with high power sonicator at ultrasound frequency of 20 kHz under various conditions (treatment time: 3, 6 and 9 min, sample temperature: 20, 40 and 60 °C, and amplitude: 60, 90 and 120 μm). The aromatic profiles of juices showed that, compared to the untreated samples of juices and nectars, ultrasonic treatment led to the formation of new compounds (which were not present in the untreated samples) or to the disappearance of compounds that were found in the untreated samples. Samples treated at the highest amplitude (120 μm) were used for evaluation and comparison with untreated and pasteurised samples using electronic tongue study. Principal component analysis confirmed the results of electronic tongue study, which showed that the ultrasound-treated and pasteurised juices had different scores compared to the untreated samples.Ultrazvuk se može primijeniti kao netermička metoda za ekstrakciju sastojaka, obradu hrane prije sušenja, zamrzavanje, inaktivaciju mikroorganizama i sl. Svrha je ovoga rada bila istražiti utjecaj ultrazvuka velike snage, te postupka pasterizacije na aromatski profil i senzorska svojstva jabučnog soka i nektara. Uzorci su obrađeni ultrazvukom velike snage i niske frekvencije od 20 kHz pri različitim uvjetima (vrijeme tretmana: 3, 6 i 9 min; temperatura: 20, 40 i 60 °C i amplituda: 60, 90 i 120 μm). Iz aromatskog se profila jabučnog soka i nektara može zaključiti da je nakon obrade ultrazvukom došlo do nastanka novih spojeva, a istodobno i do razgradnje nekih spojeva koji su pronađeni u netretiranim uzorcima. Uzorci izloženi ultrazvučnim valovima najveće amplitude (120 μm) uspoređeni su s netretiranim i pasteriziranim uzorcima pomoću elektroničkog jezika. Analizom osnovnih komponenata (engl. principal component analysis - PCA) utvrđeno je da uzorci obrađeni ultrazvukom i pasterizirani sokovi imaju drukčije vrijednosti od netretiranih sokova, što je potvrđeno i senzorskom analizom

Possible application of an electronic tongue for rapid gluten detection in gluten free flours

In this study a commercially available electronic tongue (αAstree, Alpha M.O.S.) was employed as a technique for gluten free and regular flour samples classification. Additionally, rapid determination of gluten content and other physicochemical parameters including protein content, acidity, reducing sugar content and total reducing sugar content was performed. The classification performance of the sensor array was assessed by multivariate exploratory techniques. The physicochemical characterization of gluten free and regular flours, including gluten content prediction, was obtained by artificial neural networks (ANN) modelling. The reference values of gluten content in flour samples were determined by the ELISA method, while reference values of protein content, acidity, reducing sugar content and total reducing sugar content were determined by standard analytical methods. The application of the electronic tongue, combined with ANN, in the differentiation of gluten free and regular flour samples resulted in 95.2% and 100% correct classifications, respectively. The developed ANN models for the prediction of gluten content in flour samples as well as protein content, acidity, reducing sugar content and total reducing sugar content, showed high potential of the electronic tongue as a simple and rapid technique for the prediction of gluten content and other physicochemical parameters of gluten free and regular flour samples. The results of this work implicate that the electronic tongue can be employed in the evaluation of gluten content and characterization of different flours, without time-consuming sample preparation, chemicals involved and without additional time or costs, except the initial measurements required for ANN model development

Morphological and Biochemical Diversity of Shallot Landraces Preserved Along the Croatian Coast

Shallots are a valuable minor Allium crop, and are propagated vegetatively and maintained in home gardens across generations along the Croatian coast and island areas. Shallot landraces growing along the Croatian coast fall into three genotypes: Allium cepa Aggregatum group (2n = 2x = 16), A. × proliferum (Moench) Schard. (2n = 2x = 16), and A. × cornutum Clementi ex Vis. (2n = 3x = 24), among which A. × cornutum is the most widespread. The aim of this study was to differentiate shallot accessions collected from local farmers using morphological markers. Also, the chemical composition including phenolic content, phenolic profile, total antioxidant capacity, and mineral composition, of shallot accessions was compared with that of the local landraces of common onion, and with market available shallot and common onion cultivars. Based on morphological observations and using multivariate classification, shallot landraces were classified into three distinct groups. Properties, based on which A. × cornutum can be differentiated from A. cepa Aggregatum and A. × proliferum, are stamen morphology, stamen length, leaf and scape vegetative properties, number of bulbs in cluster, cluster mass, and bulb diameter. Flower diameter and flower pedicel length differentiate A. × cornutum and A. × proliferum from A. cepa Aggregatum. Significant variability was observed in the biochemical profiles across tested accessions. Compared with the commercial common onion cultivars, local shallot accessions have higher bulb N, P, and K content. The major phenolic compounds identified in shallots were quercetin-4′-glucoside and quercetin-3,4′-diglucoside. Additionally, several other minor phenolic compounds were also identified. Morphological and biochemical profiles were evaluated using Partial Least Square (PLS) analysis. Specific morphological traits and biochemical markers for possible species identification are proposed