Roger K. Abrahamsen

Roger K. Abrahamsen
Norwegian University of Life Sciences (NMBU) · Department of Chemistry, Biotechnology and Food Science (IKBM)

Dr.scient

About

74
Publications
36,428
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
1,227
Citations
Introduction

Publications

Publications (74)
Article
Full-text available
Ultrasound (US) treatment of milk is one of several emerging technologies, often promoted as non-thermal, although a combination with heat appears to show greater potential. Bacteriocidal effects have been studied, as well as certain interesting chemical and physical changes occurring as a result of this treatment. Comparison of published results i...
Article
Yogurt should contain living strains of Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. Lactose is fermented homofermentatively by the mixed strain culture. Only the glucose moiety of lactose is fermented and galactose accumulates in the medium. Both species in the culture are thermophilic and show synergistic interactio...
Chapter
Full-text available
Antibiotic resistance poses safety risk to public health, involving the spreading of antimicrobial resistance between animals, humans and the environment,also consequently along the food chain. Limited studies have considered the spread of antibiotic resistance due to wild enterococci isolated from traditional cheese. Enterococcus faecalis and Ente...
Article
Full-text available
The diversity of seven strains of Pseudomonas spp., isolated from raw milk, was studied for growth and proteolytic and lipolytic activity in milk at 4, 8 and 22 °C. Proteolysis was demonstrated by capillary electrophoresis (CE) and the liberation of free amino acids and free fatty acids were analysed by HPLC and GC, respectively. Activity varied co...
Chapter
Yogurt is the most popular fermented dairy product and is made with thermophilic cultures of lactic acid bacteria: Streptococcus thermophilus, Lactobacillus delbrueckii subsp. bulgaricus. Set, stirred, and high protein varieties are produced. Processing of yogurt milk includes separation, fortification with milk solids non-fat, homogenization, heat...
Chapter
Nordic countries have a long tradition of milk production, and consumption of milk is high. Several of the fermented milk products commercially produced in the Nordic countries are based on traditional products and are made using mesophilic starter cultures containing strains of Lactococcus and Leuconostoc. Metabolism of lactose to lactic acid by t...
Chapter
The names of four dairy products include the word “buttermilk”, and three of these are fermented with aromatic mesophilic starter cultures containing lactococci and leuconostocs. Traditionally a byproduct from butter making from fermented cream, buttermilk can also be obtained from sweet cream. Sweet cream buttermilk can undergo a fermentation step...
Chapter
Cultured cream has several culinary uses and is produced by fermentation of homogenized and heat-treated cream with a fat content of 10%–40%. An added mesophilic starter culture of lactic acid bacteria produces lactic acid and some flavor compounds. The product has a high viscosity due to the formation of an acid gel. Cultured cream should be smoot...
Article
Full-text available
Cultured cream, produced by fermentation, has several culinary uses requiring different properties, and this may necessitate using different production technologies. Products with reduced fat content are increasingly popular, but compromised sensory properties are not desired. Here, the technology for the production of cultured cream and the influe...
Article
Full-text available
High-protein yoghurt has gained increased consumer interest over the recent years, partly driven by improvements in taste and texture; there is also greater scientific evidence on dairy protein health benefits. The protein content of yoghurt can be increased prior to fermentation by addition of dairy powder, evaporation or membrane filtration, or a...
Article
Most of the traditional dairy products of south-eastern Europe are produced from unpasteurised milk without addition of selected starter cultures. These artisanal products have an interesting biodiversity of indigenous microbiota. In Montenegro, one of the most popular traditional cheeses is Njeguši cheese, belonging to the group of hard cheeses. M...
Chapter
Brown whey cheese (“Brunost” in Norwegian) is a solid cheese obtained by heat evaporation of whey mixed with milk and cream. The cheese is hard, and has a brown color with a sweet, cooked, and caramel-like flavor. It comes in several varieties differing in the degree of browning, fat content, and milk source (cows’ or goats’ milk), and there is als...
Article
Full-text available
Scientific knowledge about the predispositions of Bosnian native breeds of sheep (Dubska) for the production of milk and milk products until recently were quite sparse and very scarce. Therefore, the aim of this study was to investigate the biochemical indicators and serum minerals, for monitoring the nutritional status. Until now subject research...
Article
The effects of casein micelle size on rheological properties of high protein (5.6% crude protein), low fat (≤0.2%) set yoghurt were investigated. Microfiltration with 0.20 μm membranes was used to fractionate skim milk with an average casein micelle size of ∼174 nm into a retentate and a permeate containing “large” (∼183 nm) and “small” (∼129 nm) c...
Article
The objective of this study was to investigate how ceramic membrane pore size and filtration temperature influence the protein fractionation of skim milk by cross flow microfiltration (MF). Microfiltration was performed at a uniform transmembrane pressure with constant permeate flux to a volume concentration factor of 2.5. Three different membrane...
Article
Naturally fermented buttermilk, prepared from soured cream or milk, was collected during two seasons from sixteen farms in northern Ethiopia, to study chemical composition and flavour compounds. Protein, fat, organic acids, carbohydrates and volatile compounds were quantified using Kjeldahl, Gerber, high-pressure liquid chromatography (HPLC) and he...
Article
To investigate the effect of the caseinomacropeptide (CMP) to true protein ratio on the functional properties of a whey protein concentrate powder, heat-induced gels with four different concentrations of CMP (0, 9, 21 and 33% true protein) at three different pH levels (4.0, 5.5, and 7.0) were made from a native whey protein concentrate and a commer...
Article
The terpene content of milk and cream made from milk obtained from cows fed indoors, and by early or late grazing, in alpine rangeland farms in Norway, were analysed for three consecutive years. The main terpenes identified and semi-quantified were the monoterpenes β-pinene, α-pinene, α-thujene, camphene, sabinene, δ-3-carene, d-limonene, γ-terpine...
Article
The microflora of a semi-hard, washed curd, Norwegian cheese with an added adjunct culture of propionic acid bacteria (PAB) was investigated throughout ripening by phenotypic and physiological tests, API test and 16S rRNA sequencing. Cheeses were made at two commercial Norwegian dairies using different milk treatments (pasteurisation versus microfi...
Conference Paper
Full-text available
The aim of this study was to explore metabolic parameters of blood from sheep, and their individual relative importance on the quality and quantity of milk ingredients, with a particular emphasis on the content of bioactive substances that may have a positive effect on human health. Samples of 127 sheep blood and milk were taken during the morning...
Article
Full-text available
The demand for whey protein is increasing in the food industry. Traditionally, whey protein concentrates (WPC) and isolates are produced from cheese whey. At present, microfiltration (MF) enables the utilization of whey from skim milk (SM) through milk protein fractionation. This study demonstrates that buttermilk (BM) can be a potential source for...
Article
The objective of this study was to investigate the effects of whey protein denaturation and whey protein:casein-ratio on the structural, rheological and sensory properties of high protein (8% true protein), low fat (<0.5% fat) yoghurt. Yoghurt milk bases were made by adding undenatured whey proteins from native whey protein concentrate (NWPC) to ca...
Article
Norvegia cheese samples (459 in total) were analysed during maturation using a broad range of analytical methods. From eight to 24 and 40 weeks there was a highly systematic development in chemical and sensory attributes. Chemical data and Fourier transform infra-red (FTIR) measurements gave almost equivalent validation results in prediction of sen...
Article
A two-step strategy was applied to overcome the quality changes observed in low-fat cheese. Cheese texture was first improved using microparticulated whey proteins (MWPs) and buttermilk (BM) as ingredients added to the cheese milk. Second, the flavour of the cheese was improved by selected Lactobacillus ssp. isolated from good-quality cheese. A 10%...
Article
Full-text available
Gamalost, a Norwegian mould (Mucor mucedo) ripened autochthonous cheese, is a potential functional food due to a high content of peptides that might reduce hypertension, however it has a high content of free amino acids which may be precursors for biogenic amines. This study aimed to investigate if Gamalost might have further health benefits or ris...
Article
The angiotensin I-converting enzyme (ACE) inhibitory activity of Gamalost cheese, its pH 4.6-soluble fraction, and Norvegia cheese was monitored before and after digestion with human gastric and duodenal juices. Both Gamalost and Norvegia cheeses showed an increased ACE-inhibitory activity during gastrointestinal digestion. However, only Norvegia s...
Article
Full-text available
Gamalost, a mould-ripened semi-hard traditional Norwegian cheese, has previously been shown to have a very high angiotensin I-converting enzyme (ACE) inhibition potential compared to other cheeses. In this study the development of the ACE-inhibiting peptides in Gamalost was characterized during ripening. The maximum ACE inhibitory activity of the p...
Article
Full-text available
Spontaneously fermented buttermilk was studied in 140 dairy farms and 8 cooperatives in northern Ethiopia to understand processing practices, status of buttermilk processing during fasting and opportunities and constraints of buttermilk processing. Households and cooperatives were interviewed using pretested formal questionnaire and semi-structured...
Article
The growth and survival of cheese lactic acid bacteria (LAB) on milk fat globule membrane (MFGM) isolated from bovine milk and on monosaccharides found in MFGM glycoconjugates were studied. The LAB studied were selected lactobacilli strains isolated from Norwegian semi-hard cheese, a starter Lactococcus sp. and the potential cheese contaminant Ente...
Article
The objective of this paper was to evaluate the relevance of data from quality scoring methodology of ISO/IDF performed by expert assessors for the sensory quality control of cheese. The approach to this evaluation was comparison of quality scoring with sensory quantitative descriptive data from a trained panel and consumer preference data. Signifi...
Article
The study investigated bacterial transfer to cooked thick porridge via ladles and hands during serving in 29 households in Lungwena, rural Malawi. Household stored water used for hand and ladle washing, was contaminated with Escherichiacoli and Staphylococcus.aureus from hands of members of the household or from contaminated ladles used in food pre...
Article
There is demand for non-destructive monitoring of eye formation in cheese during ripening. The objective of this work was to develop a simple method based on existing equipment in the dairy industry. Images were acquired using a conventional, low resolution online X-ray instrument. Image processing methods for detecting eyes of cheese and measuring...
Article
Full-text available
Buttermilk (BM) and whey are bi-products of the dairy industry, and have stabilizing and emulsifying properties. Micro-particulated whey proteins (MWP) may act as fat replacers in foods. Dairy-based custards added BM and MWP were investigated. Addition of MWP increased G′ significantly. Acceptable rheological properties in custards with essentially...
Article
Full-text available
We previously described the characteristics of LAB isolated from naturally fermented milk produced in Zimbabwe. Among these isolates, strain Lactococcus (L.) lactis subsp. lactis biovar. diacetylactis C1 produced acceptable fermented milk to a sensory panel despite the presence of a slight malty flavour. This strain also showed good growth in milk...
Article
The influence of ripening temperature and seasonality on sensory attributes during maturation of cheese was studied in two different semi-hard, washed curd, commercial Norwegian cheese varieties with similar gross composition. Multivariate models derived from sensory attributes of cheese demonstrated that ripening temperature and maturation time ha...
Article
The presence of food-borne pathogens, Escherichia coli 0157:H7, Staphylococcus aureus, Salmonella species, Campylobacter jejuni and non-pathogenic E. coli, in 132 home cooked food samples consisting of maize flour porridge (MFP), (n=41), fish (n=37), vegetables (n=28), beans (n=13) and "Others" (n=13), collected from 6 villages in Lungwena, Malawi...
Article
Full-text available
Lactic acid bacteria (LAB) were isolated from naturally fermented milk in Zimbabwe and characterized for developing cultures. The aim of the present work was to use potential isolates for the production of fermented milk. Heat-treated and homogenized fullfat milk was inoculated with LAB strains and incubated at 25°C for 18h. Single and pair-wise co...
Article
The approach to the term "milk quality" varies among consumers, dairies and researchers and is therefore very difficult to define. Three main elements of the term are however dealt with in this paper. An increased understanding of the nutritional value of various milk components is necessary. How breeding and feeding can influence the nutritional q...
Article
Full-text available
Sadržaj: U ovom radu su prikazani rezultati istraživanja biohemij- ske aktivnosti selektovanih sojeva bakterija mlečne kiseline izolovanih iz autohtonih fermentisanih mlečnih proizvoda sa područja Crne Gore i Srbije kao i ispitivanje mogućnosti primene ovih sojeva u industrijskoj proizvod- nji. Utvrđen je nivo rasta ispitivanih sojeva tokom ferment...
Article
Full-text available
Sadržaj: U ovom radu su prikazani rezultati istraživanja biohemij-ske aktivnosti selektovanih sojeva bakterija mlečne kiseline izolovanih iz autohtonih fermentisanih mlečnih proizvoda sa područja Crne Gore i Srbije kao i ispitivanje mogućnosti primene ovih sojeva u industrijskoj proizvod-nji. Utvrđen je nivo rasta ispitivanih sojeva tokom fermentac...
Article
A survey has been conducted of the allele frequency of genetic variants of various caseins, mainly αs1-casein, in herds of Norwegian goats located in north, west and southeast Norway. In addition, identifying the variants, milk composition, micellar size and renneting properties of the milks have been determined.
Article
Full-text available
Ghee is produced mainly by indigenous methods in Asia, the Middle-East and Africa and the methods of manufacture and characteristics vary. Some ambiguity in the definition of ghee occurs mainly due to regional differences and preferences for the product, commonly used for culinary purposes but also for particular social functions and therapeutic pu...
Article
Malty compound-producing Lactococcus lactis subsp. lactis biovar. diacetylactis strain INF-DM1, originally isolated from naturally fermented milk in Zimbabwe was used to prepare fermented milk from ordinary milk, milk enriched with 2.5% (w/v) skimmed milk powder and by 2.5% (w/v) increase in dry matter by ultrafiltration. Inoculated milk was incuba...
Article
Low fat, rindless Dutch-type cheese (20% fat/dry matter) made from cheese milk with added heat-treated lactobacilli and/or Neutrase encapsulated in DRV liposomes was brined for 5 and 16 h, which resulted in a low-salt cheese and a normal-salt cheese. Compared to the cheese with the normal-salt content, low-salt cheese obtained at maturity a signifi...
Article
Fermented milk and cheese produced by smallholders in three regions of southern Ethiopia were analysed. The fermented milk samples differed significantly in protein and fat content. One type of cheese had a high average protein content perhaps due to the higher curd cooking temperature, which may denature the whey proteins and allow their recovery...
Article
Low-fat Gouda-type cheese (200 g fat/kg dry matter) was made on a pilot plant scale from cheesemilk to which heat-treated lactobacilli and/or Neutrase encapsulated in dehydrated rehydrated vesicles had been added. In cheese containing added Neutrase, there was increased proteolysis after the first day following cheesemaking. The cheese with added h...
Article
Lactose-negative mutants of Lactococcus lactis subsp. lactis and Lacto-coccus lactis subsp. cremoris with good autolytic properties were used at two different levels in addition to the normal starter in Gouda-type cheesemaking experiments. Increased numbers of bacteria were observed in fresh cheese, and the pH changes during ripening were as normal...
Article
Quarg samples produced from thermized cultured milk, pH 4·5, had better keeping quality at 7°C than controls produced without thermization. Thermization improved the quality of cold-stored quargs and reduced proteolysis in control quargs and in those produced from milk containing 5 or 50 ng/ml of proteinase from Pseudomonas fluorescens P1. Quargs p...
Article
The effect of threonine on the biochemical activity of yogurt starter was investigated by the addition of L-threonine to cows' and goats' milk in two concentrations (5 and 10mg/100g). A separate experiment was conducted to investigate the effect of free glycine on the formation of acetaldehyde from yogurt starter. Increasing amounts of glycine (1,...
Article
Yogurt starter B3 was grown in cows' milk, goats' milk I (obtained 2–3 weeks after parturition) and goats' milk II (8 months after parturition), and a number of biochemical and bacteriological parameters were recorded at intervals during incubation for 8 h at 43°C. No appreciable differences between the milks were observed for total viable count, b...
Article
A quantitative method for determination of free fatty acids in milk is described. Free fatty acids and some glycerides were extracted from milk in acetonitrile in the presence of sulfuric acid and anhydrous sodium sulfate. The filtered extract was evaporated to dryness. With use of strong anion-exchange resin as heterogeneous basic catalysts, the f...
Article
The chemical composition of Norwegian bulk collected goats' milk from the University herd was analysed during one lactation period (30 weeks, 20 samples during 1983). There was considerable variation in chemical composition during the year. Fat content decreased over the first 4 months of lactation and increased during the mountain pasture period....
Article
Syneresis from milk rennet curd has been measured by different methods, such as collecting whey at intervals after cutting (Marshall, 1982), or using a tracer method (Beeby, 1959). The latter method gives the opportunity to cut and stir the curd, as with ordinary cheesemaking. In a research project on goats milk, to measure the syneresis of rennet...
Article
Variations in the biochemical performance of 2 DL-type mixed strain starters CH 01 and FDn grown in a sample of skimmed goat's milk I (obtained 2–3 weeks after parturition) and of goat's milk II (8 months after parturition) were studied, and results compared with those of the cultures grown in skimmed cow's milk. The initial levels of citrate diffe...
Article
Quality characteristics of goat's milk yoghurt made from homogenized and non-homogenized concentrates prepared by vacuum evaporation, addition of dried skimmed goat's milk, reverse osmosis or ultrafiltration were observed. Yoghurts made from ultrafiltered milk gave the best flavour and viscosity, whilst homogenization of the concentrates also incre...

Network

Cited By

Projects

Project (1)
Project
This project aims to characterize milk from six Norwegian native dairy cattle breeds. Characterisation of possible unique or unknown milk properties is important in the work for a sustainable conservation. A previous study have revealed that allelic frequencies were markedly different between the Nordic/Baltic cattle breeds. Some milk proteins alleles (such as the B variant of κ-casein) associated with improved technological properties of the milk, such as renneting and cheese yield, were found at significantly higher frequencies in the “old” Norwegian breeds when compared to “modern” breeds, such as the Norwegian Red (NRF). Moreover, detailed knowledge of milk composition and technological and nutritional properties remain largely unknown of these breeds. This study will provide important knowledge about the milk quality and genetic information of native Norwegian cattle breeds and evaluate whether these breeds possess traits of technological value, or in other ways varies from milk from NRF.