Comparison of the effect of ultraviolet light, ozone and heat treatment on muesli quality

I. Lignicka*, A. Balgalve, K. Ābelniece and A.M. Zīdere-Laizāne

Felici LLC, Rigas gatve 8, LV-2164, Adazi, Adazu novads, Latvia
*Correspondence: ilva.lignicka@musli.lv

Abstract:

Various muesli processing technologies can be used to lower microbiological parameters. It is necessary to find the best treatment technology to ensure that the product can meet various regulatory limits and to increase the shelf life of the product. The aim of this study was to compare the effect of ultraviolet light, ozone treatment and sterilisation on muesli quality. Muesli samples with dried fruits were tested, comparing the change in total plate count, yeast count and mould count. Short-wave ultraviolet (UV-C) light with a wavelength of 254 nm was used for ultraviolet light treatment, and the product was treated for 1, 2, and 5 minutes. As for ozone treatment, the samples were treated with an ozone concentration of 35 ppm for 30 minutes. Heat sterilisation was performed using sterilisation mode 25-30-50 (heating, holding, cooling), 119 °C, 2.2×10⁵ Pa. Ultraviolet light and ozone treatment did not have a significant impact on total plate count, yeast count and mould count. Heat sterilisation had the most significant effect on muesli sample microorganism level, total plate count, yeast count and mould count level were 10 log cfu g^-1.

Key words:

Effects of fertilization on Picea abies stands situated on drained peat soils

G. Cekstere¹*, A. Osvalde¹, V. Nollendorfs¹, A. Karlsons¹, J. Pormale¹, P. Zalitis², G. Snepsts², S. Minova³, L. Jankevica³ and M. Laivins²

¹University of Latvia, Institute of Biology, Laboratory of Plant Mineral Nutrition, Miera street 3, LV-2169, Salaspils, Latvia
²Latvian State Forest Research Institute ‘Silava’, Riga street 111, LV-2169, Salaspils, Latvia
³University of Latvia, Institute of Biology, Laboratory of Experimental Entomology and Microbiology, Miera street 3, LV-2169, Salaspils, Latvia
*Correspondence: gunta.cekstere@lu.lv

Abstract:

Norway spruce used for afforestation of drained peat soils frequently has low productivity and decay in a long-term, which could be related to soil chemical composition and nutrient status. The research aim was to elucidate the effect of PSM on new Norway spruce plantings (1st experiment) and 20-year-old spruce stands (2nd experiment) on drained peat soils by evaluating: (1) nutrient accumulation in soil-plant system, (2) soil microbiological activity, (3) health status of spruce individuals, (4) growth intensity and productivity of spruce, (5) changes in composition of vascular plant and moss species. The study was conducted at two forest (Myrtillosa turf.mel.) sites in Latvia, each consisting of two plots: control and treated with PMS (100 g m^-2 in September 2007, 50 g m^-2 in April 2008). During 2008–2016, regular analysis of soil, spruce needles, soil microbiology, assessment of tree crown vitality, stand productivity, inventory of vascular plant and moss species were done. The results showed that the fertilization with PMS resulted in a significantly improved K, Ca, Zn, and N status of trees, crown vitality and up to three times increased tree growth parameters at both experiments during the study period. The average count of bacteria and fungi in soil of fertilized plots, accompanied by a remarkable variability in the study years, was significantly higher only for the 1st experiment. Fungi: bacteria ratio for the fertilized and control plots differed significantly only for the 1st experiment. Significant increase of cover with nitrophilic plant (Urtica dioica, Antriscus sylvestris, Rubus idaeus) and moss (Plagiomnium cuspidatum, P. ellipticum) species at both fertilized sites were stated.

Key words:

microbiology, mineral nutrition, Norway Spruce, productivity, vegetation