Grete Skrede

Phenolic compounds in strawberry (Fragaria x ananassa Duch.) fruits: Composition in 27 cultivars and changes during ripening.

Phenolic compounds in fruits of 27 cultivars of strawberry (Fragaria x ananassa Duch.) grown in Norway were characterised and quantified by HPLC-DAD-MS(n). Total phenolic content, calculated as the sum of the individual compounds, varied 2.3-fold among cultivars, i.e., from 57 to 133mg/100g of fw. There were significant differences among cultivars in concentration of all phenolic compounds. The highest variation between cultivars was found for cinnamoyl glucose (0.6-24.9mg/100g of fw). Concentration of anthocyanins, the most abundant class of phenolic compounds in the majority of the cultivars, varied from 8.5 to 65.9mg/100g of fw. Flavan-3-ols (11-45mg/100g of fw) and ellagitannins (7.7-18.2mg/100g of fw) contributed on average 28% and 14% to total phenolic contents in the strawberry cultivars, respectively. In three cultivars harvested at three stages of ripeness, anthocyanins and cinnamic acid conjugates were the compounds most affected by ripening. The anthocyanin profile for the individual cultivars was only slightly affected by ripening and growing conditions.

Commercial antioxidants control lipid oxidation in mechanically deboned turkey meat

Effects of commercial rosemary antioxidants on oxidative stability of mechanically deboned turkey meat (MDTM) compared with Trolox C (vitamin E), ascorbic acid (vitamin C) and control without antioxidant were investigated. Antioxidants were added to meat at three levels. Thiobarbituric acid (TBA) assay and dynamic headspace gas chromatography were used to assess the effects of commercial antioxidants on lipid stability of MDTM during 7 months of frozen storage. Increased levels of TBA-reactive substances (TBARS) and volatile carbonyl compounds were noticed in all meat samples during storage, however most distinctly in meat without antioxidants. Retarding effect of antioxidants on the development of oxidation depended on the level and type antioxidants. Trolox C-a water soluble, synthetic derivative of vitamin E possessed the greatest antioxidative activity reflected by the lowest values of TBARS and volatile compounds. Ascorbic acid was less efficient than Trolox C and Biolox HT-W (rosemary), but more potent than most rosemary extracts in suppressing lipid oxidation especially in the long term frozen storage MDTM. The DPPH() method confirmed that antioxidant activity depends on the concentration of active compounds present in the samples available to scavenge the free radicals formed during the storage period. Supplementation of MDTM with antioxidants could be an alternative method to prevent oxidative degradation of the meat during frozen storage when vacuum packaging is not practical.

Instrumental colour analysis of farmed and wild Atlantic salmon when raw, baked and smoked

Abstract Flesh colour of eight canthaxanthin-pigmented farmed and eight astaxanthin-pig-mented with Atlantic salmon (Salmo salar L.) was measured by instrumental analysis. The colour of raw, baked and cold smoked flesh from cultured and wild salmon was compared using reflectance spectra transformed into CIE (1976) L ∗ a ∗ b ∗ values. In this system L ∗ represents lightness of salmon flesh colour, a ∗ redness and b ∗ yellowness. CIE (1976) L ∗ a ∗ b ∗ values obtained with a portable instrument (Minolta Chroma Meter) showed that intensity of redness ( a ∗ ) of raw, baked and smoked salmon increased with increasing carotenoid concentration of the raw flesh, while lightness ( L ∗ ) decreased. Intensity of yellowness ( b ∗ ) was not significantly influenced by carotenoid concentration. Baking and smoking caused a ∗ to decrease, while L ∗ increased. Values obtained by the portable instrument were in good accordance with corresponding values obtained with a HunterLab LabScan II sphere spectrocolorimeter. The reflectance ratio R 650 R 510 of raw, baked and smoked salmon flesh was significantly correlated to carotenoid concentration, but to a lesser extent than CIE (1976) a ∗ values. The present analyses did not reveal colour differences between farmed and wild salmon except for those caused by differences in carotenoid concentration.

Lactic acid fermentation of wheat and barley whole meal flours improves digestibility of nutrients and energy in Atlantic salmon (Salmo salar L.) diets

The effects of lactic acid fermentation of wheat and barley whole meal flours (WMF) on digestibility parameters in Atlantic salmon were studied. The WMFs were inoculated with a specific Lactobacillus strain and fermented for 16 h at 30 °C prior to mixing with other feed ingredients and processing by extrusion. Fermentation of the WMFs significantly decreased total starch (P<0.01) and total mixed-linked (1–3)(1–4)-β-glucan (P<0.001) contents in both cereals. Soluble β-glucans decreased (P<0.001) from 25.2 to 12.0 g kg−1 dry matter in barley WMF during fermentation. In Experiment 1, where diets with 24% untreated wheat or barley WMF and 12%, 24%, or 36% fermented WMFs were fed to Atlantic salmon (0.5 kg) for 25 days, there were indications of improved starch and fat digestibility by fermentation. Experiment 2 comprised diets containing 24% untreated or fermented wheat or barley WMFs fed to each of triplicate groups of Atlantic salmon (0.5 kg) during a 17-day experimental period. This experiment showed that protein (P<0.001), fat (P<0.05) and energy (P<0.001) were more efficiently digested in diets with wheat than in diets with barley. Apparent digestibility of starch was greatly improved by fermentation (P<0.001), more in barley diets (from 47.5% to 67.0%) than in wheat diets (from 51.7% to 65.4%). Improvements in digestibility of fat (P<0.05) and energy (P<0.001) were obtained by fermenting the cereals. The absorption of Na was higher for salmon fed wheat than barley diets (P<0.05). Fermentation resulted in improved Na absorption (P<0.01); from 68.8% to 73.2% for wheat diets and from 60.3% to 71.7% for barley diets. Fermentation caused a significant (P<0.05) improvement in Zn absorption from 32.7% to 40.5% for wheat diets and from 33.2% to 43.5% for barley diets. This may be related to the significant reduction in phytic acid levels seen in both fermented cereals (P<0.001). In conclusion, the potential of wheat and especially barley as ingredients in salmon diets is greatly improved by fermentation.

Comparison of various types of starch when used in meat sausages.

Technological and sensory properties of meat sausages formulated with 4·0% of either potato flour, modified (acetylated distarch phosphate) potato starch, wheat, corn or tapioca starch were compared. Sausages were analyzed after cooking at temperatures between 65 and 85°C followed by storage at 5°C and -25°C. Characteristics evaluated were weight loss during cooking and storage, instrumentally and sensory assessed firmness, taste and smell of sausages. The results revealed differences in the suitability of starches for use in meat sausages. Part of the differences could be ascribed to differences in gelatination properties of the starches. With the criteria used for evaluating quality, potato flour was rated as the best suited starch followed by wheat starch while tapioca was rated as the least suited. Corn starch required cooking temperatures above 75°C and showed relatively low freeze/thaw stability. The modified potato starch stored well both above and below the freezing point.

Evaluation of carrot varieties for production of deep-fried carrot chips — I. Chemical aspects

Abstract Carrot variety had a significant influence on the dry matter, redness ( a ∗ ) and sucrose content, while cultivation site (environmental condition) had a significant influence on the dry matter, lightness ( L ∗ ), redness ( a ∗ ), sucrose and glucose content. The chemical content of raw carrots could be used to predict the quality of carrot chips by means of three factors when partial least-squared analysis was applied. Factor 1 was explained by the difference in colour at the different cultivation sites, factor 2 by the difference in sucrose content in the different varieties, while factor 3 covered both colour and sugars, and grouped the cultivation sites in three where the carrots had similar chemical composition.

Evaluation of carrot varieties for production of deep fried carrot chips—III. Carotenoids

Abstract Carotene contents of four carrot (Daucus carota L.) varieties, grown at six latitudes in Norway, demonstrated that carrots grown at two locations far south had the highest carotene contents, while no effect of variety was seen. Carotene contents of carrot chips correlated significantly with those of raw carrots and averaged 88% of initial amount, about 20% being identified as 9-cis β-carotene. The carotenes corresponded to 4140 retinol equivalents (RE) per 100 g chips, demonstrating carrot chips as a good source of carotenes. For raw carrots, CIE (1976) L∗, a∗ and Hue° values correlated significantly with carotene content, while for chips, a∗, b∗ and Hue° values correlated with carotene content.

Quantitative determination of myoglobin and haemoglobin in beef by high-performance liquid chromatography

Three different HPLC columns were tested for their suitability for the analysis of myoglobin and haemoglobin in beef. Complete separation of the two proteins was obtained with an anion exchange column and a column based on hydrophobic interaction. With the latter column a recovery close to 100% was obtained for both proteins when they were added to meat extracts. For both proteins, the standard error of the mean for repeated analyses of ground beef was less than 2% of the detected amount. The method is considered as suited for quantitative routine analysis of myoglobin and haemoglobin in beef and beef products.

Effects of lactic acid fermentation on wheat and barley carbohydrate composition and production performance in the chicken

Effects of dietary inclusion of dried lactic acid fermented wheat or barley whole meal flours (WMF) on chicken performance were studied. WMFs were fermented for 16 h at 30 ◦ Cb y aLactobacillus strain isolated from a Norwegian rye sourdough. Four diets containing 600 g wheat WMF kg −1 (0, 200, 400 and 600 g fermented kg −1 ) and three diets containing 600 g barley WMF kg −1 (0, 400 and 600 g fermented kg −1 ) were used. Each treatment comprised 125 one-day-old sexed chickens (Ross) were fed on experimental diets until slaughtering at 35 days. Average weight, feed intake and feed:gain ratio in the 0–14, 14–35 and 0–35-day periods were recorded. At day 35, six chickens of each sex from each diet were slaughtered for determination of dressing percentage and abdominal fat. Fermentation significantly reduced levels of total and soluble dietary fibre in cereal WMF. In barley WMF, total-glucans decreased from 36.9 to 29.3 g kg −1 dry matter (DM) and soluble -glucans from 17.8 to 12.6 g kg −1 DM after fermentation. The effects of fermentation on dietary fibre and -glucans were reflected in the analysis of the experimental diets. Total starch was not significantly affected by fermentation. Cereal source and level of fermented WMF in the diets significantly affected chicken body weights. At 14 days, average weights were increased from 277 to 333 g for wheat diets, and from 252 to 322 g for barley diets, when untreated WMF was entirely substituted by fermented WMF. Linear regressions showed significant increase in average weight at 14 days with increasing levels of fermented wheat (R 2 = 0.448 ∗∗∗ ) and fermented barley (R 2 = 0.604 ∗∗∗ ). The effects of fermentation on weights at 14 days were similar for wheat and barley, as there was no significant difference between the regression slopes. Feed intake during the 0–14-day period was not significantly affected by the content of fermented cereal in the diet. Increasing level of fermented cereal significantly improved feed:gain ratio during the 0–14-day period for both

Vitamin C, total phenolics and antioxidative activity in tip-cut green beans (Phaseolus vulgaris) and swede rods (Brassica napus var. napobrassica) processed by methods used in catering

BACKGROUND Retention of nutrients in vegetables during blanching/freezing, cooking and warm-holding is crucial in the preparation of both standard and therapeutic diets. In the present study, conventional cooking in water, and cooking by pouch technology (boil-in-bag, sous vide) were compared in their ability to retain vitamin C, total phenolics and antioxidative activity (DPPH and FRAP) in industrially blanched/frozen tip-cut green beans and swede rods. RESULTS After conventional cooking, 50.4% total ascorbic acid, 76.7% total phenolics, 55.7% DPPH and 59.0% FRAP were recovered in the drained beans. After boil-in-bag cooking, significantly (P < 0.05) higher recoveries were obtained, i.e. 80.5% total ascorbic acid, 89.2% total phenolics, 94.8% DPPH and 92.9% FRAP. Recoveries after sous vide cooking were comparable to those of boil-in-bag cooking. By conventional cooking, 13.5-42.8% of the nutrients leaked into the cooking water; by sous vide about 10% leaked to the exuded liquid, while no leakage occurred by boil-in-bag cooking. Warm-holding beans after cooking reduced recoveries in all components. Recoveries in swede rods were comparable but overall slightly lower. CONCLUSION Industrially blanched/frozen vegetables should preferably be cooked by pouch technology, rather than conventional cooking in water. Including cooking water or exuded liquid into the final dish will increase the level of nutrients in a meal. Warm-holding of vegetables after cooking should be avoided.