Utjecaj sastava atmosfere na oksidaciju mljevenog oraha tijekom skladištenja pri 20 °C

The aim of this study is to determine the impact of atmosphere on the oxidation of ground walnut during storage at 20 °C. Seven varieties of walnut (Juglans regia L.) were ground and stored under O2 or N2 atmospheres in hermetically sealed vials for 10 months at room temperature. Antioxidative potential, total phenolic content, fatty acid composition, and oxidative degradation products were determined after 10 months of storage. Cultivar, atmosphere and cultivar×atmosphere interactions significantly influenced the antioxidative potential. Cultivar and atmosphere significantly influenced the content of total polyphenols, with more polyphenols found in walnut stored in the N2 atmosphere. The mass fraction of unsaturated linolenic acid tended to decrease during storage under the O2 atmosphere; statistically significant differences were only found between individual varieties. The O2 atmosphere also resulted in an increase in the synthesis of oxidative degradation products. Among the degradation products, hexanal was the most abundant volatile compound, followed by 1-octen-3-ol, octanal, as well as the mixture of 2-octenal and 1-octen-3-ol. In general, higher concentrations of these degradation products were found in walnut stored under the O2 atmosphere, although these differences were statistically significant only between individual varieties for some compounds.Svrha je ovoga rada bila utvrditi utjecaj sastava atmosfere na oksidaciju mljevenog oraha tijekom skladištenja pri 20 °C. Sedam je sorata oraha (Juglans regia L.) samljeveno i skladišteno 10 mjeseci na sobnoj temperaturi u hermetički zatvorenim posudama u atmosferi s povećanim udjelom kisika ili dušika, pri čemu su određivani sljedeći parametri: antioksidacijski potencijal, ukupni fenoli, sastav masnih kiselina i produkti oksidacije. Kultivar, sastav atmosfere, te interakcija između kultivara i sastava atmosfere bitno su utjecali na antioksidacijski potencijal. Sastav je ukupnih polifenola uvelike ovisio o kultivaru i sastavu atmosfere, a više je polifenola pronađeno u uzorcima skladištenim u atmosferi s povećanim udjelom dušika. Udjel se nezasićene linolenske kiseline smanjio u orasima pohranjenim u atmosferi s povećanim udjelom kisika, a statistički su značajne razlike primijećene jedino između pojedinačnih sorata. U atmosferi s povećanim udjelom kisika nastalo je više produkata oksidacije, pri čemu najviše hlapljivih produkata, i to heksanala, zatim 1-oktan-3-ola, oktanala, te smjese 2-oktenala i 1-okten-3-ola. Veće su koncentracije tih produkata utvrđene u uzorcima skladištenim u atmosferi s povećanim udjelom kisika, iako su bitne razlike pronađene jedino između pojedinih sorata

Influence of UV-B Light Emitting Diodes on Colour Development and Accumulation of Polyphenols and Antioxidants in Apple Skin

UV light provoked stress can evoke antioxidant defence system and consequently induces the synthesis of several phytochemical compounds. The aim of the present study was to investigate the influence of UV-B light irradiation on surface colour and synthesis of some bioactive compounds in apples skin of cultivars ‘Elstar’ and ‘Jonagold’. Half of each apple was shaded with aluminium foil to compare irradiated and non-irradiated parts of skin. Apple fruits were exposed to constant UV-B light at 310 nm in chamber for 13 days at 8.5 °C. The UV-B light emitting diodes were positioned ca. 13 cm above the apple fruit and the average irradiance fruit received was 4.6 μW/cm2. Measurements of colour parameters (L*, a*, b*) were performed on the same spots of irradiated and non-irradiated surface of each apple fruit before and after 7, 10 and 13 days of storage constant UV-B light irradiation. All apple fruits started to develop red colour on the irradiated surface. The antioxidant potential, ascorbic acid content, total phenolic compounds, six flavonols and anthocyanin cyanidin-3-galactoside were quantitatively evaluated. Apple skins exposed to UV-B light irradiation contained significantly more total phenolic compounds and had higher antioxidant potential as compared to non-irradiated. UV light treated apple skin contained more cyanidin-3-galactoside and flavonols

Utjecaj žute svjetlosti valne duljine od 590 nm, emitirane pomoću LED svjetiljki, na skladištenje plodova jabuke, rajčice i paprike babure

The objective of this study is to investigate the eff ects of irradiation from light-emitting diodes (LEDs) on several fruits during storage. To improve storage and increase the contents of some bioactive compounds, apple, tomato and red bell pepper fruits were exposed to yellow light emitted from the diodes at 590 nm. The contents of ascorbic acid, total phenolics, total flavonoids and several pigments were investigated, along with the antioxidant potential. The colour parameters (L*, a* and b*) and firmness of the fruit were also determined. After 7 days of LED light irradiation, there was significantly higher total phenolic content and antioxidant potential in apple peel extracts. The irradiated fruit of tomato had significantly higher levels of total phenolic compounds, and the fruit of red bell pepper had significantly higher antioxidant potential. LED light had no effects on the colour parameters, although there was a tendency to accelerate colour development. Apple fruit irradiated with LED light was significantly less firm. Among twelve analysed pigments, significantly more β-carotene was detected in LED light-irradiated apple and bell pepper fruit, more α-tocopherol and γ-tocopherol in bell pepper fruit, and more lutein in apple peel and bell pepper fruit. The applied LED light slightly accelerated the ripening of the studied fruit, and affected the synthesis of some of the secondary metabolites.Svrha je ovoga rada bila ispitati utjecaj svjetlosti koje emitiraju LED svjetiljke na skladištenje nekoliko vrsta plodova. Jabuka, rajčica i paprika babura izlagane su žutoj svjetlosti valne duljine od 590 nm radi poboljšanja trajnosti plodova i povećanja udjela nekih bioaktivnih sastojaka. Određene su sljedeće vrijednosti: udjeli askorbinske kiseline, ukupnih fenola, ukupnih flavonoida i nekoliko pigmenata, te antioksidacijski potencijal plodova. Nakon sedam dana izlaganja plodova LED svjetlosti došlo je do znatnog povećanja udjela ukupnih fenola i antioksidacijskog potencijala u ekstraktima kore jabuke, povećanja udjela ukupnih fenola u plodu rajčice, te do povećanja antioksidacijskog potencijala ploda paprike babure. LED svjetlost nije utjecala na karakteristike boje, iako je donekle ubrzala razvoj boje plodova. Izlaganje jabuke LED svjetlosti uzrokovalo je mekšanje ploda. Ispitani su udjeli dvanaest pigmenata u plodovima, te je pronađeno znatno više β-karotena u jabuci i paprici baburi, više α- i γ-tokoferola u paprici, te više luteina u kori jabuke i plodu paprike babure nego u kontrolnim uzorcima. LED svjetlost je donekle ubrzala sazrijevanje plodova i utjecala je na sintezu nekih sekundarnih metabolita

Disaccharides: Influence on Volatiles and Phenolics of Sour Cherry Juice

The food industry is continuously developing ingredients, processing methods and packaging materials to improve the quality of fruit products. The aim of this work was to study the effect of sugars, a common ingredient in the food industry, on phenolics and volatiles of sour cherry juice. Sucrose, trehalose and maltose chemical isomers were chosen for this investigation. All sugars influenced the evaluated parameters. Samples with maltose addition had lower, while samples with sucrose and trehalose addition had higher anthocyanin content than the control sample. Generally, trehalose had a higher positive effect on volatiles with the desired flavor note

A New Aroma Index to Determine the Aroma Quality of Roasted and Ground Coffee During Storage

The staling of ground roasted coffee blend was studied over one year of storage. Solid phase microextraction-gas chromatography-mass spectrometry analysis was carried out to identify and semi-quantify 40 volatile compounds. We focused on volatile compounds related to the ageing of coffee: methanethiol, propanal, 2-methylfuran, 2-butanone, 2,3-butanedione, 2-furfurylthiol and hexanal. Changes in sensory properties of coffee beverage prepared from the ground roasted coffee samples during storage in laminate packages (PET/ aluminium foil/PE) under air atmosphere, under nitrogen or in punctured packages were determined. Samples were stored at (23±2) °C and (40±10) % relative humidity. The reference coffee was packed similarly in laminate packages under nitrogen and stored at (-20±1) °C. Applying a statistical assessment of the results, we found the loss of most volatile compounds from all stored coffee samples, including even those stored under freezing conditions. The ratios of 2-methylfuran/2-butanone and methanethiol/hexanal proved useful indicators of staling. Our new proposed aroma index, the ratio of 2-furfurylthiol/ hexanal, proved to be the most effective, giving high correlation coefficients (R≥0.80) with aroma freshness for coffee brews prepared from the ground roasted coffee stored under different conditions at room temperature

Novi indeks arome za određivanje kakvoće mljevene pržene kave tijekom skladištenja

The staling of ground roasted coffee blend was studied over one year of storage. Solid phase microextraction-gas chromatography-mass spectrometry analysis was carried out to identify and semi-quantify 40 volatile compounds. We focused on volatile compounds related to the ageing of coffee: methanethiol, propanal, 2-methylfuran, 2-butanone, 2,3-butanedione, 2-furfurylthiol and hexanal. Changes in sensory properties of coffee beverage prepared from the ground roasted coffee samples during storage in laminate packages (PET/ aluminium foil/PE) under air atmosphere, under nitrogen or in punctured packages were determined. Samples were stored at (23±2) °C and (40±10) % relative humidity. The reference coffee was packed similarly in laminate packages under nitrogen and stored at (-20±1) °C. Applying a statistical assessment of the results, we found the loss of most volatile compounds from all stored coffee samples, including even those stored under freezing conditions. The ratios of 2-methylfuran/2-butanone and methanethiol/hexanal proved useful indicators of staling. Our new proposed aroma index, the ratio of 2-furfurylthiol/ hexanal, proved to be the most effective, giving high correlation coefficients (R≥0.80) with aroma freshness for coffee brews prepared from the ground roasted coffee stored under different conditions at room temperature.U radu je istraženo starenje mješavine mljevene pržene kave tijekom jedne godine. Mikroekstrakcijom na čvrstoj fazi i plinskom kromatografijom u kombinaciji s masenom spektrometrijom identificirano je i djelomično kvantificirano 40 hlapljivih spojeva. Težište je rada na hlapljivim spojevima (metantiol, propanal, 2-metilfuran, 2-butanon, 2,3-butandion, 2-furfuriltiol i heksanal), povezanim sa starenjem kave. Tijekom skladištenja uočene su promjene senzorskih svojstava napitaka pripremljenih od mljevene pržene kave, pakirane u višeslojnu ambalažu (PET/aluminijska folija/PE) u atmosferi zraka ili dušika, te u probušenu ambalažu. Uzorci su skladišteni pri temperaturi od (23±2) °C i relativnoj vlažnosti od (40±10) %. Referentni je uzorak slično pakiran u višeslojnu ambalažu u atmosferi dušika i skladišten pri temperaturi od (-20±1) °C. Statističkom obradom podataka utvrđeno je da se u svim skladištenim uzorcima, pa čak i u zamrznutim, izgubio veliki dio hlapljivih spojeva. Omjeri 2-metilfurana i 2-butanona, te metantiola i heksanala pokazali su se kao korisni pokazatelji starenja. Novi predloženi indeks arome (omjer 2-furfuriltiola i heksanala najdjelotvorniji je pokazatelj, s velikim koeficijentom korelacije (R≥0.80) u usporedbi sa svježinom arome napitaka pripremljenih od mljevene pržene kave, skladištene pri različitim uvjetima na sobnoj temperaturi

Novi indeks arome za određivanje kakvoće mljevene pržene kave tijekom skladištenja

The staling of ground roasted coffee blend was studied over one year of storage. Solid phase microextraction-gas chromatography-mass spectrometry analysis was carried out to identify and semi-quantify 40 volatile compounds. We focused on volatile compounds related to the ageing of coffee: methanethiol, propanal, 2-methylfuran, 2-butanone, 2,3-butanedione, 2-furfurylthiol and hexanal. Changes in sensory properties of coffee beverage prepared from the ground roasted coffee samples during storage in laminate packages (PET/ aluminium foil/PE) under air atmosphere, under nitrogen or in punctured packages were determined. Samples were stored at (23±2) °C and (40±10) % relative humidity. The reference coffee was packed similarly in laminate packages under nitrogen and stored at (-20±1) °C. Applying a statistical assessment of the results, we found the loss of most volatile compounds from all stored coffee samples, including even those stored under freezing conditions. The ratios of 2-methylfuran/2-butanone and methanethiol/hexanal proved useful indicators of staling. Our new proposed aroma index, the ratio of 2-furfurylthiol/ hexanal, proved to be the most effective, giving high correlation coefficients (R≥0.80) with aroma freshness for coffee brews prepared from the ground roasted coffee stored under different conditions at room temperature.U radu je istraženo starenje mješavine mljevene pržene kave tijekom jedne godine. Mikroekstrakcijom na čvrstoj fazi i plinskom kromatografijom u kombinaciji s masenom spektrometrijom identificirano je i djelomično kvantificirano 40 hlapljivih spojeva. Težište je rada na hlapljivim spojevima (metantiol, propanal, 2-metilfuran, 2-butanon, 2,3-butandion, 2-furfuriltiol i heksanal), povezanim sa starenjem kave. Tijekom skladištenja uočene su promjene senzorskih svojstava napitaka pripremljenih od mljevene pržene kave, pakirane u višeslojnu ambalažu (PET/aluminijska folija/PE) u atmosferi zraka ili dušika, te u probušenu ambalažu. Uzorci su skladišteni pri temperaturi od (23±2) °C i relativnoj vlažnosti od (40±10) %. Referentni je uzorak slično pakiran u višeslojnu ambalažu u atmosferi dušika i skladišten pri temperaturi od (-20±1) °C. Statističkom obradom podataka utvrđeno je da se u svim skladištenim uzorcima, pa čak i u zamrznutim, izgubio veliki dio hlapljivih spojeva. Omjeri 2-metilfurana i 2-butanona, te metantiola i heksanala pokazali su se kao korisni pokazatelji starenja. Novi predloženi indeks arome (omjer 2-furfuriltiola i heksanala najdjelotvorniji je pokazatelj, s velikim koeficijentom korelacije (R≥0.80) u usporedbi sa svježinom arome napitaka pripremljenih od mljevene pržene kave, skladištene pri različitim uvjetima na sobnoj temperaturi

The Influence of Atmosphere on the Oxidation of Ground Walnut During Storage at 20 °C

The aim of this study is to determine the impact of atmosphere on the oxidation of ground walnut during storage at 20 °C. Seven varieties of walnut (Juglans regia L.) were ground and stored under O2 or N2 atmospheres in hermetically sealed vials for 10 months at room temperature. Antioxidative potential, total phenolic content, fatty acid composition, and oxidative degradation products were determined after 10 months of storage. Cultivar, atmosphere and cultivar×atmosphere interactions significantly influenced the antioxidative potential. Cultivar and atmosphere significantly influenced the content of total polyphenols, with more polyphenols found in walnut stored in the N2 atmosphere. The mass fraction of unsaturated linolenic acid tended to decrease during storage under the O2 atmosphere; statistically significant differences were only found between individual varieties. The O2 atmosphere also resulted in an increase in the synthesis of oxidative degradation products. Among the degradation products, hexanal was the most abundant volatile compound, followed by 1-octen-3-ol, octanal, as well as the mixture of 2-octenal and 1-octen-3-ol. In general, higher concentrations of these degradation products were found in walnut stored under the O2 atmosphere, although these differences were statistically significant only between individual varieties for some compounds