Tag Archives: polyphenols

346-355 A. Avena, L. Ozola and A. Keke
Evaluation of phenolic compound composition of Sambucus nigra berries grown in Latvia
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Evaluation of phenolic compound composition of Sambucus nigra berries grown in Latvia

A. Avena*, L. Ozola and A. Keke

Latvia University of Life Sciences and Technologies, Faculty of Agriculture and Food Technology, Institute of Food, Lielā iela 2, LV-3001, Jelgava, Latvia
*Correspondence: anita.avena@gmail.com

Abstract:

Phenolic compounds in agricultural raw materials can vary within a species and can be affected by a combination of such factors as growing region, weather conditions and fruit ripeness. Climatic differences between the southern, central and northern parts of Europe can cause differences in the phenolic compounds present in the plant. The research was aimed to investigate the phenolic compounds of berries of Sambucus nigra varieties grown for commercial production in Latvia. During the study four elderberry varieties were analysed – ‘Haidegg 17’, ‘Korsör’, ‘Haschberg’ and ‘Emma’. All samples were analysed for total phenolic compound content (TPC), DPPH free radical scavenging activity and individual phenolic compounds. In addition, sample pH and total soluble solids (TSS) were measured. Results showed that ‘Emma’ berry samples had the highest value of TSS content – 10.5% (°Bx) and the lowest pH value – 3.65. The variety ‘Korsör’ showed the lowest TSS content – 8.1% (°Bx) as well as the lowest TPC and DPPH free radical scavenging activity, the variety ‘Haschberg’ showed the highest pH value. The variety ‘Haidegg 17’ stood out with a high TPC. In total six phenolic compounds were identified and quantified in the analysed samples – gallic acid, catechin, chlorogenic acid, p-coumaric acid, sinapic acid and 3,5-dihydroxybenzoic acid. According to the obtained results, it was evident that the indicators for some parameters differ from the information available in the literature about the composition of berries of crops grown in other regions. This suggests that it is worth further researching elder tree varieties grown in northern climate.

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2715–2726 A. Kikas,, R. Rätsep,, H. Kaldmäe, A. Aluvee and A.-V. Libek
Comparison of Polyphenols and Anthocyanin Content of Different Blackcurrant (Ribes nigrum L.) Cultivars at the Polli Horticultural Research Centre in Estonia
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Comparison of Polyphenols and Anthocyanin Content of Different Blackcurrant (Ribes nigrum L.) Cultivars at the Polli Horticultural Research Centre in Estonia

A. Kikas¹,*, R. Rätsep¹,², H. Kaldmäe¹, A. Aluvee¹ and A.-V. Libek¹

¹Estonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, Polli Horticultural Research Centre, Uus 2, Polli, EE69108 Viljandi county, Estonia
²Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, ERA Chair for Food (By-) Products Valorisation Technologies, Fr. R. Kreutzwaldi 1, EE51006 Tartu, Estonia

Abstract:

The evaluation of blackcurrant cultivars and their fruit properties at the Polli Horticultural Research Centre has been active since 1945. In addition to the assessment of biological and economic properties of cultivars, it is essential to pay attention to fruit quality. In 2014, the laboratory building of Polli Horticultural Research Centre was reconstructed within the PlantValor competence centre project, enabling to introduce HPLC methods for the determination of polyphenolic compounds in fruit quality analysis. In 2017 and 2018, the fruit quality of 37 blackcurrant cultivars of different geographical origin (Belarus, Estonia, Finland, Latvia, Lithuania, Norway, Poland, Russia, Scotland, Sweden and Ukraine) was analysed. All cultivars were grown in the genetic resources collection (2008–2019) located at the Polli Horticultural Research Centre. The main aim of the study was to analyse the content of polyphenols and anthocyanins for selecting suitable blackcurrant genotypes for breeding programmes, fruit production and possible product development. In two consecutive years of the study, the total polyphenols content in the fruits of different cultivars varied 290–634 mg 100 g-1 fresh weight (fw) and the anthocyanins 183–471 mg 100 g-1 fw.

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1673–1679 R.A. Harbah, T.V. Meledina, and A.A. Morozov
The effect of yeast growth stages on the absorption of polyphenols
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The effect of yeast growth stages on the absorption of polyphenols

R.A. Harbah*, T.V. Meledina, and A.A. Morozov

Saint-Petersburg State University of Information Technologies, Mechanics and Optics (ITMO University), Faculty of Food Biotechnology and Engineering, Kronversky pr., 49, RU197101 St Petersburg, Russia
*Correspondence: razan.harbah@mail.ru

Abstract:

Colloidal stability of beer is one of the most critical challenges facing the brewing industry. In brewing, stabilization agents are widely used to remove colloids such as proteins and polyphenols. However, the removal efficiency of polyphenols depends on the yeast, which adsorbs these compounds on its surface. The adsorption of polyphenols on the yeast surface is associated with the zeta potential of the cell wall, which correlates with the mannan content in them. The purpose of the study was to investigate the role of yeast strains in adsorption of polyphenols (increasing colloidal stability of beer) and the correlation of this property with the mannan content in the cell wall during the fermentation. Two S. cerevisiae strains were used in this study, and the specific growth rate of yeast, the specific rate of change in the polyphenol content and the mannan content were determined. The results of this study showed that the highest mannan content in yeast was after 9 hours (the end of exponential growth phase). Its content was 10.97% by weight of dry matter in the yeast S. cerevisiae Californian Lager (M54), and 13.69% in the yeast S. cerevisiae Belgian Wit (M21). The desorption of polyphenols was observed during the period from 9 to 24 hours of fermentation, where an increase in the content of polyphenols in the medium was observed. Based on these results, it is necessary to remove the yeast at the end of the exponential growth phase to increase the colloidal stability of the beer.

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1284–1298 T. Evstigneeva, N. Skvortsova and R. Yakovleva
The application of green tea Extract as a source of antioxidants in the processing of dairy products
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The application of green tea Extract as a source of antioxidants in the processing of dairy products

T. Evstigneeva*, N. Skvortsova and R. Yakovleva

International Research Centre Biotechnologies of the Third Millennium ITMO University, St. Lomonosov 9, 191002, Saint-Petersburg, Russian Federation
*Correspondence: romihka@mail.ru

Abstract:

 Regular consumption of foods containing antioxidants reduces the bodily content of free oxygen radicals, which can cause pathological changes and premature organism aging. The aim of this work was the development of the formulations and determination of the parameters for the production of cottage cheese products with polyphenol fraction of green tea extract as a source of plant antioxidants. Parameters to obtain extracts with the high content of extracted substances and high antioxidant activity were determined. Optimal performance was achieved by brewing dry green tea leaves with (70 ± 2) °C water, followed by steeping at the same temperature for 10 minutes with continuous mechanical stirring. Optimal dry tea leaves to water ratio used for tea extracts’ preparation was identified. The level of tea extract in cottage cheese products’ recipes was determined. The flavour fillers which combine the best with green tea extract and taste were identified. The positive effect of tea extract component on shelf life of cottage cheese product was shown.

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969-978 L. Klavina
A study on bryophyte chemical composition–search for new applications
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A study on bryophyte chemical composition–search for new applications

L. Klavina

University of Latvia, Department of Environmental Science, Raina Blvd. 19, Riga, LV-1586, Latvia; e-mail: laura.klavina@lu.lv

Abstract:

Bryophytes are the taxonomic group in the plant kingdom represented with about 25’000 species. They contain a high number of biologically active compounds; however their use as a food source is negligible. The aim of this paper is to evaluate bryophyte chemical composition and new possible applications. In order to evaluate bryophyte potential usage as a raw food material, bryophyte basic chemical content and the secondary metabolite profile was determined. To obtain best results bryophyte secondary metabolite extraction options has been studied. Couple of extraction methods were used (conventional, ultrasound, microwave, supercritical CO2 extraction etc.) and different solvents (ethanol, water etc.). A total concentration of polyphenols and substances determining free radical scavenging activity has been determined. The extracts obtained from bryophytes have remarkable antioxidant activity, the extent of which depends on the extraction conditions and bryophyte species. Comparison of five extraction methods and several solvents indicates that microwave assisted extraction and supercritical CO2 extraction is the most promising approach to obtain highest yields of extractives.

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