Protein Quality and Energy Density of Leek (Allium porrum L) as Influenced by Water and Nitrogen Supply and Plant Age at Harvest

Leeks were cultivated under conditions differing in level of nitrogen (N) supply (100 kg N ha^-1, 160 kg N ha^-1, 220 kg N ha^-1, 280 kg N ha^-1), level of water supply (normal, low) and time of harvest (September, October, November). Based on chemical analysis and balance studies on rats the nutritive value of the 26 batches of leek was determined. The protein content of the leeks increased progressively from 90 g kg^-1 DM to 163 g kg^-1 DM with N-supply. This increase in protein was associated with a reduction of all essential amino acids (g per 16 g N) and, subsequently, a reduction of the biological value. Protein and energy digestibilities increased with level of N-supply. Leeks harvested in September had a higher protein content, but had at the same time the lowest biological value as compared to leeks harvested in October or November. This was due to a lower content of essential amino acids (g per 16 g N) in leeks harvested in September as compared to leeks of later harvest. Only small differences between the two levels of water supply were observed in the chemical composition of the leeks. The content of non-starch polysaccharides (NSP) was rather high in all samples of leek (approximately 240–280 g kg^-1 DM) and appeared to be unaffected by the growth conditions applied in the investigation. Soluble-NSP constituted approximately half of the total NSP. © 1997 SCI.     

Changes in Anthocyanins and Polyphenolics During Juice Processing of Highbush Blueberries (Vaccinium corymbosum L.)

Frozen blueberries ( Vaccinium corymbosum L.) were processed into juice and concentrate, and the changes in anthocyanin pigments and polyphenolics (cinnamates, procyanidins, flavonol glycosides) were monitored. While juice yield was 83%, only 32% of the anthocyanins were recovered in single-strength juice. Flavonol, procyanidin and chlorogenic acid recoveries in juice were 35%, 43%, and 53%, respectively. The proportion of polyphenolics remaining in the press-cake residue ranged from 1% (chlorogenic acid) to 18% (anthocyanins). Pronounced losses of anthocyanins and polyphenolics during milling and depectinization are believed to be due to native polyphenol oxidase. Losses during concentration ranged from 1.5% (anthocyanins) to 20% (procyanidins). Striking changes occurred in the anthocyanin profile with malvidin glycosides being most stable and delphinidin glycosides the least.     

A comparison of the carbon balances of a natural lake (L. Orträsket) and a hydroelectric reservoir (L. Skinnmuddselet) in northern Sweden

Carbon balances were calculated for the summer stratification period of 2001 for the hydroelectric reservoir L. Skinnmuddselet (created in 1989) and the natural L. Ortr?sket, and estimated on annual basis for both lakes. The reservoir and the lake have similar chemical characteristics and are located in adjacent catchments in the northern part of Sweden. Our main hypothesis was that the CO(2) production and emissions from the reservoir, L. Skinnmuddselet, would be greater than in the natural L. Ortr?sket, due to the decomposition of flooded vegetation and peat. The carbon balances showed that the total production of CO(2) per unit lake surface area during the summer was very similar in the natural lake and the reservoir (31.3 g Cm(-2) in L. Ortr?sket and 25.3 g Cm(-2) in L. Skinnmuddselet). The sediments were the major CO(2) source in the reservoir, while most of the mineralization in the natural lake occurred in the water column. On annual basis the natural L. Ortr?sket produced and emitted more CO(2) per unit of lake surface area than the reservoir L. Skinnmuddselet since mineralization proceeded during winter when L. Skinnmuddselet was emptied for electricity production. Therefore, the potential for CO(2) emission was not greater in the reservoir than in the natural lake.     

Glazed spaces in Nordic climates

A semi-climatized zone in the shape of a glazed space is heated to some degree by solar radiation and to some degree by excess heat or heat loss from the main and fully insulated part of the building. Such a space will not offer full thermal comfort for permanent occupancy during the winter season, but it is useful for secondary functions such as circulation, storage, physical activities, etc. During the summer season glazed spaces will also be very attractive for ordinary occupancy.

A condition for energy conservation is that these spaces are not heated directly but utilize heat loss and possibly excess heat from the adjoining buildings. If they are properly positioned and constructed, they will also function as solar collectors.

The energy reduction potential will vary greatly with the relative size of the spaces, with the system installed, and with possibilities for long term storage. If the glazed space covers relatively large parts of the adjoining buildings, the reduced heat loss from these may be considerable. If in addition a certain minimum temperature can be kept in the glazed space, the need for heating in the adjoining buildings may be minimal.

Abroad such spaces are often used consciously as architectural elements due to their special spatial character. In countries like Norway they may in addition serve several needs resulting from the special climatic conditions.

SINTEF has developed energy conservation systems based on this concept and has tested them in experimental buildings. One example is the three solar energy houses in the Heimdal low energy dwellings project which totals 14 houses. Another example is a day care centre now under development for the local student union.     

The combined effect of rosemary (Rosmarinus officinalis L.) and modified atmosphere packaging as protection against warmed over flavour in cooked minced pork meat

Rosemary (dried leaves ofRosmarinus officinalis L.) added to cooked meat balls (minced pork) was found to retard the formation of warmed over flavour (WOF) during chill storage. The spice was added to pork meat (Longissimus dorsi) balls in an amount acceptable for the product, as evaluated by a sensory panel (0.05% of total weight). After cooking (water bath, internal temperature 80°C), the meat balls were packed using five atmosphere packaging conditions: (i) air; (ii) 5% O₂/95% N₂; (iii) 3% O₂/97% N₂; (iv) 1% O₂/99% N₂; and (v) 100% N₂. During chill storage (5°C), the sensory quality of the reheated meat balls was evaluated by a trained sensory panel, and lipid oxidation was followed by measurement of thiobarbituric acid reactive substances (TBARS). The combination of decreased O₂ atmosphere in the packages and addition of rosemary resulted in a significantly (p<0.05) lower amount of TBARS and a significantly (p<0.05) better sensory score.

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Gemeinsamer Effekt von Rosmarin (Rosmarinus officinalis L.) und Verpackung in modifizierter Atmosphäre auf den Aufwärmegeschmack (WOF) von wärmebehandeltem, gehacktem Schweinefleisch

Zusammenfassung Rosmarin (getrocknete Blätter vonRosmarinus officinalis L.), erwärmten Fleischklößen (gehacktes Schweinefleisch) zugesetzt, hinderte die Entwicklung des Aufwärmgeschmacks (warmed over flavour) während der Kühllagerung. Das Gewürz wurde den aus Schweinefleisch (Longissimus dorsi) hergestellten Fleischklößen in einer für das Produkt akzeptablen Menge zugegeben, beurteilt von einem sensorischen Panel (0.05% des Totalgewichtes). Nach der Wärmebehandlung (Wasserbad, Zentrum-Temperatur 80°C) wurden die Fleischklöße in fünf unterschiedlichen und kontrollierten Atmosphären wie folgt verpackt: (i) Luft; (ii) 5% O₂/95% N₂; (iii) 3% O₂/97% N₂; (iv) 1% O₂/99% N₂ und (v) 100% N₂. Während der Kühllagerung (5°C) wurde die sensorische Qualität der wiedererwärmten Fleischklöße von einem geschulten Panel beurteilt und die Lipid-Oxidation durch Messung der Thiobarbitursäure-reaktiven Substanzen (TBARS) beobachtet. Die Kombination von ermäßigtem Sauerstoffgehalt in den Verpackungen mit der Zugabe von Rosmarin ergab eine signifikant (p<0.05) niedrigere Menge TBARS wie auch signifikant (p<0.05) bessere Punkte in der sensorischen Beurteilung.

     

Antioxidative activity of summer savory (Satureja hortensis L.) and rosemary (Rosmarinus officinalis L.) in minced, cooked pork meat

The sensory intensity measured as theabsolute threshold value of spice andrecognition of spice was evaluated for summer savory and rosemary in meat balls. The values forabsolute threshold value of spice were found to be significantly lower for rosemary than for summer savory. The antioxidative activity of the spices was analysed in two accelerated model systems and in a storage experiment. In one of the model systems, oxidation was accelerated by heat and by an elevated pressure of oxygen. Both spices significantly improved the oxidative stability of the meat balls in this model system. In the second model system metal catalyst oxidation in a meat slurry was used and a reduction in the oxidative processes in samples containing the spices was again shown. In both model systems a slightly higher antioxidative activity was seen for rosemary compared to summer savory. In the storage experiment, the spices were added at a sensorially acceptable level and the heat-treated meat balls were stored at 5°C. A significant reduction in the development of warmed-over flavour (WOF) caused by the addition of spices was measured by a reduction in 2-thiobarbituricacid-reactivesubstances (TBARS) and in hexanal. A reduction in TBARS of approximately 30% in meat balls containing added spices was seen independently of packaging in 1% oxygen or in atmospheric air and the reduction (30%) was constant throughout the storage period.     

Suitability of four blackcurrant cultivars for industrial syrup production

The four blackcurrant cultivars Øjebyn, Ben Nevis, Ben Lomond and Silvergieter have been evaluated with reference to their suitability for syrup production. The examination was based on sensory and physico-chemical characterisation, and was performed on the berries themselves and the syrup. The results show that Øjebyn is less suitable for syrup production, while Ben Nevis and Ben Lomond differ insignificantly in most qualities from the reference cultivar, Silvergieter. Criteria for the evaluation of cultivars for industrial suitability are discussed.     

Evaluation of a mathematical model for prediction of lipid oxidation in heat-treated beef during chill storage

Ground beef was heated to temperatures ranging from 60 to 120 °C and was stored at 5 °C for 0–7 days. The oxidative status of the meat samples was quantified by sensory evaluation and by measurement of thiobarbituricacid-reactive substances (TBARS). A model describing the effect of moderate heating temperatures (60–80 °C) and chill storage time on the development of TBARS has been developed previously, and experiments were conducted to evaluate and extend this model. It was demonstrated that the model could be used for prediction of the individual effects of heating time and heating temperature. The level of TBARS during chill storage almost doubled when the heating temperature increased from 60 °C to 70 °C, but it was unaffected by increasing heating temperatures from 70 °C to 100 °C. Higher heating temperatures caused a remarkable increase in the oxidative stability, TBARS hardly increased during storage after heating to 110 °C or 120 °C. A more elaborate model was developed to describe the effect of heating temperatures in the range of between 60 °C–120 °C on development of TBARS, but the predictive value turned out to be unsatisfactory. The sensory evaluations were highly correlated with TBARS, and the use of TBARS as a measure of warmed-over flavour was verified.     

Yeast derived from lignocellulosic biomass as a sustainable feed resource for use in aquaculture

The global expansion in aquaculture production implies an emerging need of suitable and sustainable protein sources. Currently, the fish feed industry is dependent on high‐quality protein sources of marine and plant origin. Yeast derived from processing of low‐value and non‐food lignocellulosic biomass is a potential sustainable source of protein in fish diets. Following enzymatic hydrolysis, the hexose and pentose sugars of lignocellulosic substrates and supplementary nutrients can be converted into protein‐rich yeast biomass by fermentation. Studies have shown that yeasts such as Saccharomyces cerevisiae, Candida utilis and Kluyveromyces marxianus have favourable amino acid composition and excellent properties as protein sources in diets for fish, including carnivorous species such as Atlantic salmon and rainbow trout. Suitable downstream processing of the biomass to disrupt cell walls is required to secure high nutrient digestibility. A number of studies have shown various immunological and health benefits from feeding fish low levels of yeast and yeast‐derived cell wall fractions. This review summarises current literature on the potential of yeast from lignocellulosic biomass as an alternative protein source for the aquaculture industry. It is concluded that further research and development within yeast production can be important to secure the future sustainability and economic viability of intensive aquaculture. © 2016 Society of Chemical Industry     

Characterisation of the dominant bacterial population in modified atmosphere packaged farmed halibut (Hippoglossus hippoglossus) based on 16S rDNA-DGGE

It is not well understood why Atlantic halibut (Hippoglossus hippoglossus) has longer shelf-life than most other white fish species. Our approach was to examine the microbiological diversity of the spoilage microbiota during modified atmosphere (MA) packaging of farmed Atlantic halibut. Portions were packaged with gas mixtures of CO(2):N(2) and CO(2):O(2) (50%:50%) and with air as a reference. The packages were stored at 4 degrees C and samples were taken 6 times during the 23 days of storage. Analyses with molecular techniques (PCR-DGGE) determined profiles of the bacterial populations in the various samples and sequencing detected the bacterial species present. In addition, samples were analysed for microbial, chemical and sensory parameters. The shelf-life was 10-13 days when stored in air and between 13 and 20 days for MA packages, with oxygen-enriched packages suggested as the better gas mixture, based on microbial growth and sensory scores. From sequence analyses of the bacterial population Photobacterium phosphoreum and Pseudomonas spp. were found to dominate in the halibut. Brochothrix thermosphacta was found in most samples at the end of the storage period. Shewanella putrefaciens was found sporadically and in low concentrations based on microbial methods, but not detected by PCR-DGGE.