Pernille Baardseth

Comparison of Small and Large Deformation Rheological Properties of Wheat Dough and Gluten

ABSTRACT The rheological properties of dough and gluten are important for end-use quality of flour but there is a lack of knowledge of the relationships between fundamental and empirical tests and how they relate to flour composition and gluten quality. Dough and gluten from six breadmaking wheat qualities were subjected to a range of rheological tests. Fundamental (small-deformation) rheological characterizations (dynamic oscillatory shear and creep recovery) were performed on gluten to avoid the nonlinear influence of the starch component, whereas large deformation tests were conducted on both dough and gluten. A number of variables from the various curves were considered and subjected to a principal component analysis (PCA) to get an overview of relationships between the various variables. The first component represented variability in protein quality, associated with elasticity and tenacity in large deformation (large positive loadings for resistance to extension and initial slope of dough and gluten ...

Effect of selected antioxidants on the stability of dehydrated mashed potatoes

The antioxidants TBHQ, alpha-tocopherol, Prolong P (rosemary, thyme, marjoram mixture) or ascorbyl palmitate were not found able to replace the antioxidant BHA in potato flakes production if stored for up to 24 months. Ascorbyl palmitate gave good antioxidative protection up to 16 months of storage, and also protected against carotenoid degradation better than the other antioxidants. The ascorbyl palmitate lost its antioxidative effect after longer storage.

Instrumental and sensory analysis of fresh Norwegian and imported apples

Abstract Sensory profiling, instrumental texture measurements and volatile composition was used to characterise ten Norwegian and three imported apple varieties. Principal component analysis of sensory data identified an odour/flavour-factor and a texture factor along the first and second principal component, respectively. The main volatile components separating the apples were propyl acetate, butyl acetate, 2-methylbutyl acetate, hexyl acetate, ethyl acetate, ethyl butanoate, 1-butanol, ethanol and α-farnesene. The first four mentioned volatiles were related to fruity and sweet sensory attributes, while the latter were related to sour, bitter and grassy attributes. Sensory hardness, chewiness and mushiness correlated well with instrumentally measured force and work required for penetration of the flesh. Sensory odour- and flavour attributes showed varying correlations by principal least squares regression to volatile composition and texture-data separately. Sour, sweet and grassy flavours were best explained when sensory odour- and flavour-attributes were correlated to texture-measurements and volatile composition-data at the same time.

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.

Multivariate feature extraction from textural images of bread

Abstract In order to compute the classical texture measures there is often a need to perform extensive calculations on the images and do a preprocessing in a specialised manner. Some of these texture measures are constructed to estimate specific information. Other texture measures seem to be more global in nature. The techniques presented in this paper define algorithms applied on the raw image without extensive preprocessing. We want to show that mathematical transformations of images on a vectorised form will easily enable the use of multivariate techniques and possibly model several features hidden in the images at the same time. In this paper we will compare five different methods of extracting features from textural images in food by multivariate modelling of the sensory porosity of wheat baguettes. The sample images are recorded from factorial designed baking experiments on wheat baguettes. The multivariate feature extraction methods to be treated are the angle measure technique (AMT), the singular value decomposition (SVD), the autocorrelation and autocovariance functions (ACF) and the so-called size and distance distribution (SDD) method. The methods will be tested on equal basis and the modelling of sensory porosity from extracted features is done using principal component regression (PCR) and partial least square regression (PLS). The difference between the behaviour of the methods will be discussed. The results show that all the methods are suited to extract sensory porosity but the AMT method prove to be the best in this case.

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.

Lactic acid fermentation influence on sugar content and colour of deep-fried carrot chips

Abstract Carrot chips with a light red-yellow colour were obtained by lactic acid fermentation of carrot slices in a brine prior to deep-frying. The fermentation process decreased the content of reducing sugars up to 75%, thereby restricting the extent of Maillard reactions during heating. Rinsing the slices after fermentation but prior to deep-frying enhanced sugar removal. Three strains of Lactobacillus were tested. Strain NCIMB 40450 reduced sugar levels faster than strains NCDO 1193 and NCDO 1752. The best colour properties were obtained when carrot slices were deep-fried after 24 h fermentation.

Studies on fatty acid α-oxidation in cucumber

Abstract Alpha-oxidation of fatty acids was studied in cucumber. Both differential centrifugation and average sedimentation coefficient determination suggested that the α-oxidation was particle bound and mainly localized to the mitochondrial fraction. A partly purified α-oxidation system was obtained by fast protein liquid chromatography. The activity of the α-oxidation system determined as release of 14 CO 2 was characterized with respect to inhibitors and reductant requirements. The results from this study suggest a similarity between the α-oxidation system in cucumber and that of pea leaf and cotyledons of germinating peanuts.

Roll-in shortenings effects on Danish pastries sensory properties studied by principal component analysis

The effects of 11 different shortenings, either made of milk fat or vegetable oil, at three concentrations (350, 500 and 600 g/kg) on sensory properties, and instrumental texture and colour of Danish pastries were investigated. Principal component analysis (PCA) revealed two dominating components for sensory properties; the first to shortening type and the second to shortening concentration. Results were verified by analysis of variance (ANOVA). Texture and colour were measured to verify the sensory results and analysed by the same statistical methods using PCA and ANOVA, respectively.