Inta Krasnova

Influence of Anti-Browning Inhibitors and Biodegradable Packaging on the Quality of Fresh-Cut Pears

Pears usually are used as ingredients in the production of fresh-cut fruit salads. Fruit browning in the food industry is one of the main problems, and therefore, different anti-browning inhibitors are used to maintain the quality of fresh-cut pears. The aim of this study was to evaluate the use of Japanese quince (Chaenomeles japonica) juice (QJ) as an anti-browning agent for the pear (Pyrus communis) cultivar ‘Belorusskaya Pozdnaya’ and to compare its effect to that of ascorbic acid (AA) solution, which is typically used as an anti-browning agent. In addition, the effect of biodegradable packaging material on quality of treated pears during storage was assessed, in comparison with packaging in conventional polymer pouches. Diluted 20% Japanese quince juice and 1.5% ascorbic acid solution were used as inhibitors of pear browning. Produce quality during storage of fresh-cut pears for ten days using biodegradable polilactid (PLA) containers with lids and VC999 BioPack PLA films coated with a barrier of pure silicon oxide (SiOx) was compared with that using conventional packaging with polyethylene (PE) film as a control. The quality of pears during storage was estimated by changes of colour brightness value L*, whitening index (WI), firmness (N), pH value and total soluble solid content (Brix o). The results showed that colour of fresh-cut pears was maintained better using biodegradable packaging materials and using the control anti-browning agent ascorbic acid. After nine storage days, the brightness L* value of fresh cut pears was significantly lower when conventional packaging material (PE film pouches) and treatment with Japanese quince juice was used. Grieztu augļu kvalitatīvo īpašību saglabāšanai realizācijas laikā tiek izmantoti pretbrūnēšanas apstrādes līdzekļi - inhibitori. Iepakojums ir neatņemama sastāvdaļa pārtikas produktu ražošanas un mārketinga procesos. Pētījums veikts Latvijas valsts augļkopības institūtā 2010. gadā. Pētījuma mērķis bija novērtēt pretbrūnēšanas inhibitoru apstrādes efektivitāti (20% krūmcidoniju sulas) salīdzinājumā ar 1.5% askorbīnskābes šķīduma (kontroles) un novērtēt biodegradējamo iepakojuma materiālu ietekmi uz apstrādāto griezto bumbieru kvalitāti uzglabāšanas laikā, salīdzinot ar tradicionālo parasto iepakojumu - polietilēna (PE) maisiņiem. Biodegradējamie polilaktīda (PLA) konteineri ar vākiem un VC999 BioPack PLA plēves, ar silīcija oksīda baijeru (SiOx) izmantotas grieztu bumbieru iepakošanai, bet kontroles paraugs iepakots PE plēves maisiņos. Pētījuma laikā kontrolēta bumbieru kvalitāte, krāsa, cietība, pH, šķīstošās sausnas saturs. Bumbieri (Pyrus communis) ‘Belorusskaja Pozdnaja’ nomizoti, sagriezti gabaliņos (1-1.5 cm) desmit minūtes mērcēti inhibitoru šķīdumos (1.5% askorbīnskābes šķīdumā, 20% krūmcidoniju sulas ūdens atšķaidījumā). Augļu gabaliņi notecināti, iepakoti PE plēves maisiņos, biodegradējamie iepakojumos: VC999 BioPack PLA maisiņos un PLA kārbiņās. Paraugi uzglabāti +4 ± 1 °C temperatūrā deviņas dienas. Pētījuma rezultāti rāda, ka krāsa labāk saglabājusies svaigi grieztajiem bumbieriem biodegradējamā materiāla iepakojumos, kā arī pēc apstrādes ar 1.5% askorbīnskābes šķīdumu. L * vērtība svaigi grieztajiem bumbieriem pēc deviņu dienu uzglabāšanas bija būtiski zemāka parastajos PE plēves maisiņos pēc apstrādes ar 20% krūmcidoniju sulu.

Content of Phenolic Compounds in Various Sea Buckthorn Parts

Abstract All parts of the sea buckthorn (Hippophae rhamnoides L.) plant are considered to contain large amounts of compounds that are believed to have beneficial health effects. Till now, different parts of sea buckthorn plant have been used for the treatment of diseases in traditional medicine in various countries. Nevertheless, sea buckthorn parts would be a good raw material not only for medicinal properties but also for food products with functional properties; therefore, the aim of the research was to determine the concentration of different phenolic compounds and antioxidant activity in various sea buckthorn parts. The study was conducted on parts of female and male sea buckthorn bushes. Phenolic compounds (total phenols, total flavonoids and condensed tannins) and antioxidative activity (ferric reducing antioxidant power (FRAP) free radical scavenging activity (using 2.2-diphenyl-1-picrylhydrazyl, DPPH)) in ethanolic extracts of leaves, shoots, flowers, and berries were determined using various spectrophotometric methods. The study showed that concentration of phenolic compounds differed among parts of sea buckthorn plant and among gender. Leaves of female plants proved to be the most valuable, as they contained the highest total phenol concentration (165.76 mg/g) and antioxidant activity (220.97 mg/g for FRAP and 43.76 mg/g for DPPH), while lowest values were found in young shoots of male plants (84.94 mg/g, 94.24 mg/g and 24.63 mg/g, respectively). The significant differences in chemical composition and biological activity of sea buckthorn leaves, shoots, berries, and buds indicate a need for detailed studies of their extracts, specific fractions and compounds during a whole vegetative season. Abstrakt Rakstā aplūkots fenolsavienojumu saturs dažādās smiltsērkšķu auga daļās un to antioksidatīvā aktivitāte. Kā pētījuma objekts izvēlētas sievišķo un vīrišķo augu lapas, jaunie dzinumi, zaļās ogas, kas ievāktas jūnija vidū, un ziedi, kas ievākti aprīļa beigās. Paraugiem analizēts kopējo fenolu, kopējo flavonoīdu un kondensēto tanīnu saturs, kā arī antioksidatīvā aktivitāte ar FRAP (ferric reducing antioxidantpower) un DPPH (2.2-diphenyl-1 -picrylhydrazyl) metodi. Vērtīgākā auga daļa izrādījās sievišķā auga lapas, kurām konstatēts augstākais kopējo fenolu saturs un antioksidatīvā aktivitāte, lietojot abas metodes, savukārt vismazākie minētie rādītāji bija jaunajiem dzinumiem no vīrišķā auga. Rezultāti norāda uz būtiskām atšķirībām smiltsērkšķu auga daļu ķīmiskajā sastāvā un bioloģiskajā aktivitātē, tādēļ nepieciešami padziļināti pētījumi par ekstraktiem, to frakcijām vai atsevišķiem savienojumiem un to izmaiņām visā veģetācijas sezonā.

The Influence Of Cultivation System On Biochemical Content Of Strawberry Fruits

Abstract Three cultivars ‘Zefyr’, ‘Honoeoye’ and ‘Polka’ were grown on beds mulched with black plastic or without it, as well as in low tunnels covered by transparent polyethylene film or Agronet (Pegas agro, 17 g·m-2), or without covering. The quality of fruits determined by content of ascorbic acid, titratable acidity, soluble solids, total content of phenolics and anthocyanins, antiradical activity, and radical scavenging activity (RSA) was evaluated during two seasons. Significant differences in phytochemical contents within strawberry cultivars, production seasons and cultivation methods were stated. Cultivar had the greatest influence on the content of ascorbic acid, total phenolics and RSA among all the studied factors. The amount of anthocyanins was mainly influenced by plant covering, while the annual climatic conditions had the greatest impact on the amount of titratable acidity and soluble solids. Soil mulching had the lowest influence on the chemical content of fruits.

Use of Packaging Materials for Extending the Shelf Life of Diploid Plum Variety ‘Kometa’

Polymers (films, bags and boxes) are the most widely used materials for packing of fresh fruit. Product shelf life is dependent on the packaging material barrier properties, including permeability of CO2 and O2. It focused on the uses of environmentally friendly biodegradable packaging materials for fresh fruit storage. Polypropylene, polylactic acid boxes and cardboard boxes placed in polylactic acid material bag were tested as packaging materials to extend the shelf life of diploid plum cultivar ‘Kometa’. Qualitative characteristics of plum (weight, firmness, soluble solids content and colour changes) stored at temperature +4 ± 1 °C for 20 days were evaluated. Sensory evaluation was performed using a 9-point hedonic scale. Plum in good quality can be stored at the temperature +4 ± 1 °C for 12 days on average. Selective gas and moisture barrier properties of polylactic material ensured minimal weight loss in hermetical containers, but promoted plum ripening and hence a reduction of the storage period. The results suggested that biodegradable packaging materials could be a successful alternative to the conventional polymers for plum packaging, and could contribute to reduction of environmental pollution. Polimēri (plēves, paciņas, kastītes) ir tirdzniecībā plašāk lietotie iepakojuma materiāli svaigu augļu iesaiņošanai. Produktu uzglabāšanas laiks ir atkarīgs no iepakojuma materiālu baijerīpašībām, tajā skaitā CO2 un O2 caurlaidības. Pētījums veikts Latvijas Valsts augļkopības institūtā 2008. gadāļ un vērsts uz videi draudzīgu biodegradējamo iepakojumu materiālu izmantošanu svaigu augļu uzglabāšanai. Pētījuma gaitā diploīdās šķirnes ‘Komēta’ plūmes ievietotas polipropilēna, polilaktīdskābes materiālu kārbiņās un kartona kārbiņās, kas savukārt ieliktas polilaktīdskābes plēves maisiņā. Plūmes uzglabātas 20 dienas 44 ± 1 °C temperatūrā, nosakot to kvalitatīvos rādītājus: masas zudumus, blīvuma, šķīstošās sausnas satura un krāsas izmaiņas. Plūmju sensorās analīzes veiktas, izmantojot deviņu punktu hedonisko skalu. Labā un tirdzniecībai piemērotā kvalitātē plūmes +4 ± 1 °C temperatūrā var uzglabāt vidēji 12 dienas. Polilaktīdskābes materiālu selektīvās gāzu un mitruma baijeripašības hermētiski noslēgtos iepakojumos nodrošināja minimālus mitruma zudumus, taču paātrināja plūmju nogatavošanos, samazinot uzglabāšanas laiku. Pētījuma rezultāti liecina, ka plūmju iepakošanu biodegradējamos iepakojuma materiālos var veiksmīgi izmantot kā alternatīvu tradicionālajiem polimēru materiāliem, un tas būtiski mazinātu vides piesārņojumu.

The effect of pre-treatment methods on the quality of dehydrated candied Japanese quince fruits during storage

Candied quince is one of the most popular processing products of Japanese quince (Chaenomeles japonica) in Latvia. During the storage of dehydrated fruit, the colour turns darker, thus negatively influence the overall quality and consumers’ acceptability of the product. The aim of the present study was to evaluate the effectiveness of different anti-browning agents in combination with fruit blanching and soaking as a type of pre-treatment to preserve the colour of candied quince during 8-months storage. The fruit were harvested at various maturity stage (i.e. unripe, semi ripe and ripe) with the following pre-treatment using three anti-browning agents (l-cysteine, NATRApHASE®ABAF and Natureseal® AS1). Hunter L (whiteness/darkness), a (redness/greenness) and b (yellowness/blueness) values were used to measure change in colour. These values were also used for calculation of the total colour change (ΔE*). Considering blanching and soaking as a type of treatment. Best results were obtained with blanching treatment. L* values decreased significantly after dehydration, showing that the samples became darker, during the further 8-months storage, L* values increased, positively influencing the colour of the tested fruit. The data obtained using the Analytic Hierarchy Process Analysis revealed that 0.3% l-cysteine was the best for effective prevention of colour change during long-term storage among the tested agents.

Antibacterial Activity of Some Plants of Traditional Herbal Medicine in Vitro against Escherichia Coli Originated from Liquid Pig Manure

The present study was designed to evaluate antimicrobial resistance of Escherichia coli (E.coli) isolated from liquid pig manure and to determine in vitro the antibacterial activity of nine traditional Latvian medical plants against various profiles of isolated antibiotic resistant E.coli. The commensal E.coli and extended-spectrum Beta-lactamase (ESBL)-producing E.coli isolates were tested to 12 antibiotics by the disk diffusion method. The in vitro antimicrobial activities of extracts of plants were evaluated, using well diffusion technique. Results showed that overall 72% of the E.coli isolates were antibiotic resistant, being divided into 55.5% resistant to up to three different classes of antibiotics and 44.5% resistant to four or more (up to 6) different classes. In the present study, majority of tested plants (Urtica dioica, Hypericum perforatum, Hippophae rhamnoides, Viburnum L., Vaccinium macrocarpon L., Cuminum cyminum L.) have not demonstrated antimicrobial activity to E.coli isolates. However, the oil extract of leaves of Plantago major, aqueous extract of green husk of Juglans regia L. and ethanol extract of seeds of Tropaeolum majus L. demonstrated activity against test cultures.