| 1. |
- Ofstad, R., et al.
(författare)
-
Liquid-holding capacity and structural changes in comminuted salmon (Salmo salar) muscle as influenced by pH, salt and temperature
- 1995
-
Ingår i: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 28:3, s. 329-339
-
Tidskriftsartikel (refereegranskat)abstract
- The loss of liquid in salmon muscle comminuted with salt was studied as a function of pH and heating temperature. A factorial experiment was designed to compare the effects of; the raw material, NaCl concentration, pH, degree of comminution and heating temperature in order to evaluate both main effects and interaction effects. The liquid-holding capacity was measured by a low speed centrifugation net test. The changes in microstructure in the samples were investigated by light microscopy using fat- and protein-staining techniques. The heating temperature, pH, NaCl concentration, variation of raw material and degree of comminution influenced liquid loss according to a second-order interaction linear model. The interaction effect between low pH, low salt concentration and high temperature was strongest. Addition of salt extracted the myofibrillar proteins and resulted in a homogeneous protein matrix with few intact fibres and uniformly dispersed fat droplets. Liquid loss was closely related to the microstructure of the comminutions. When heated above 30 °C, enlarged pores and gaps, some of them forming channels, occurred in the protein matrix. In comminutions prepared with a low salt concentration and/or a low pH the more frequent presence of pores and gaps enhanced the liquid loss. © 1995 Academic Press Limited.
|
|
| 2. |
- Andersson, Karin, et al.
(författare)
-
Including environmental aspects in production development : A case study of tomato ketchup
- 1999
-
Ingår i: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 32:3, s. 134-141
-
Tidskriftsartikel (refereegranskat)abstract
- An environmental Life Cycle Assessment (LCA) study of a specific tomato ketchup was carried out. The objectives of the work were to illustrate how LCA can be used in production development; to investigate the influence of the geographical location of certain processes; and to find ways to improve the product's environmental performance. In the screening LCA which includes the whole life cycle, the packaging and processing sub-systems were found to be significant in the total environmental impact made by ketchup. Accordingly, six alternative systems, including packaging, processing and transportation, were modelled and simulated. The environmental impact categories included were energy use, global warming, acidification, eutrophication, photo-oxidant formation and the generation of radioactive waste. It was concluded that the current geographical location of the production of ketchup is preferable; the contributions to acidification can be reduced significantly; and the environmental profile of the product can be improved for either the type of tomato paste currently used or a less concentrated tomato paste. A shift to a less concentrated paste would also mean that traditional quality parameters of the ketchup could be improved. © 1999 Academic Press.
|
|
| 3. |
- Andersson, Karin, et al.
(författare)
-
Influence of oxygen concentration and light on the oxidative stability of cream powder
- 1998
-
Ingår i: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 31:2, s. 169-176
-
Tidskriftsartikel (refereegranskat)abstract
- The production of volatile oxidation products and consumption of oxygen were measured in cream powder stored for 35 weeks at 30 °C in darkness or exposed to fluorescent light. The headspace of the bottles contained either air (209 mL O 2/L) or 13, 3.5, 0.4 or 0.3 mL/L oxygen in nitrogen. The exposure to light strongly influenced both the rate of hexanal production and oxygen consumption. After the first 5 weeks of storage in light, significantly different oxygen-dependent increases in hexanal were found for all samples. Although the samples stored in darkness showed a much smaller hexanal increase, it was still significant during storage. After 35 weeks of storage, the dark-stored sample in air showed a highly significant larger hexanal increase than all the other samples stored in darkness, but after the same storage period, the hexanal increase in the 13, 3.6 and 0.4 mL O 2/L samples was the same. The production of the Strecker aldehyde, 3-methylbutanal, was found to depend on light and to some extent on oxygen concentration, which indicates that lipid oxidation also influenced the conditions of the Maillard reaction. © 1998 Academic Press Limited.
|
|
| 4. |
- Andersson, Karin, et al.
(författare)
-
Influence of oxygen concentration on the flavour and chemical stability of cream powder
- 1998
-
Ingår i: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 31:3, s. 245-251
-
Tidskriftsartikel (refereegranskat)abstract
- Descriptive sensory analysis and analysis of hexanal content were performed on cream powder stored in darkness at different oxygen concentrations at 30 °C for up to 45 weeks. The headspace of the samples contained 209 (air), 13, 3.6, 0.4 or 0.3 m/L oxygen/L headspace gas. All samples stored with reduced oxygen content were, with one exception, significantly different from the air-packed sample after 25 as well as after 45 weeks of storage, both in their hexanal concentration and according to sensory analysis. However, there were no significant sensory differences between the samples stored with reduced oxygen for 25 or 45 weeks. Analysis of the hexanal concentration in the samples was a more sensitive method than sensory analysis for detecting differences between samples stored for the same length of time. Furthermore, some of the samples with reduced oxygen concentration were found to differ significantly in their hexanal concentration. Significant differences between samples before storage and samples stored for 25 or 45 weeks, regardless of oxygen concentration, were found by both sensory and chemical analyses. © 1998 Academic Press.
|
|
| 5. |
- Andersson, Karin, et al.
(författare)
-
Influence of oxygen concentration on the storage stability of cream powder
- 1997
-
Ingår i: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 30:2, s. 147-154
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of low oxygen concentrations on lipid oxidation during storage of cream powder was studied. The powder was packed with oxygen concentrations of 209 mL/L, 17 mL/L, 8.3 mL/L, 3.4 mL/L, 1.5 mL/L, 0.7 mL/L and 0.6 mL/L and stored in darkness at 30°C for 29 weeks. To follow oxidation, the formation of volatile oxidation products and oxygen consumption were measured. After 7 weeks of storage a significant (P <0.01) hexanal development was already seen in all the samples, and the hexanal content was directly related to the initial oxygen content, with one exception, the 0.6 mL/L sample, which had a slightly (but not significantly, P >0.05) higher hexanal content than the 0.7 mL/L sample. There were only small differences in hexanal formation between the samples packed with oxygen concentrations below 3.4 mL/L. This could be due to a more pronounced influence of oxygen diffusion at these low levels of oxygen, leading to a diffusion-controlled oxidation. Other volatiles, not produced by lipid oxidation, also increased during storage. The formation of Strecker aldehydes was found to be oxygen-dependent, whereas the formation of 2-alkanones was not. Measurement of oxygen consumption was not sufficient to detect differences in oxidation rate between the samples packed with 17 mL/L oxygen and less. © 1997 Academic Press Limited.
|
|
| 6. |
- Lennersten, M., et al.
(författare)
-
Influence of different packaging materials on lipid oxidation in potato crisps exposed to fluorescent light
- 1998
-
Ingår i: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 31:2, s. 162-168
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of packaging materials, with various light transmission characteristics, on protection against lipid oxidation in potato crisps exposed to fluorescent light, was studied. The materials used were transparent oriented polyethylene terephtalate (OPET), transparent coextruded oriented polypropylene (OPP), cavitated white OPP, metallized extruded OPP and unbleached paper. The concentrations of pentanal and hexanal in the headspace were used as indicators for lipid oxidation. Neither transparent OPET nor transparent co-extruded OPP afforded any protection against light-induced lipid oxidation in potato crisps, compared with storage without packaging material, and the concentrations of pentanal and hexanal increased after just 7 d. The concentration of pentanal and hexanal in potato crisps stored under unbleached paper and cavitated white OPP increased after 77 and 97 d respectively, while no increase could be detected in potato crisps stored under metallized OPP for 5 months. The more rapid oxidation in potato crisps stored under cavitated white OPP, compared with when stored under metallized OPP, proved that visible light, at wavelengths longer than 380 nm, is capable of causing lipid oxidation in potato crisps. © 1998 Academic Press Limited.
|
|
| 7. |
- Ofstad, R., et al.
(författare)
-
Factors influencing liquid-holding capacity and structural changes during heating of comminuted cod (gadus morhua l.) muscle
- 1996
-
Ingår i: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 29:42006, s. 173-183
-
Tidskriftsartikel (refereegranskat)abstract
- The loss of liquid in cod muscle finely comminuted with salt was studied as a function of heating temperature from 5 to 70 °C. Three different groups of raw material were tested: wild and farmed maturing cod and wild post-spawn cod. The effects of ionic strength, pH and heating temperature upon liquid-holding capacity were examined either individually or simultaneously by using a general linear statistical model. The liquid-holding capacity was measured by a low-speed centrifugation net test. The microscopic changes of the comminuted samples were evaluated by light microscopy. The intact muscle, used as raw material, was investigated with light and transmission electron microscopy. The liquid loss was very low and almost constant between 5 and 30 °C, and increased rapidly thereafter at elevated temperatures. NaCl concentration, pH, heating temperature and interactions among these factors influenced the liquid released according to a first-order interaction linear model. Upon comminution with salt, most of the fibre structure is lost and a homogeneous phase is formed from the depolymerized myofibrils. Pores and gaps appeared in the protein matrix upon heating, enhancing the liquid loss. Melted collagen was seen either as a thin film or as an aggregated network structure, depending on the temperature, in the aqueous phase filling the pores and gaps. Wild, maturing cod possessed better liquid-holding capacity at higher heating temperatures than did both farmed and post-spawn fish, owing to different fibre structure. Post-spawn fish underwent a more severe degradation than did the maturing fish during ice-storage. ©1996 Academic Press Limited.
|
|
| 8. |
- Thorvaldsson, K., et al.
(författare)
-
Rheology and structure of heat-treated pasta dough : Influence of water content and heating rate
- 1999
-
Ingår i: Lebensmittel-Wissenschaft + Technologie. - : Academic Press. - 0023-6438 .- 1096-1127. ; 32:3, s. 154-161
-
Tidskriftsartikel (refereegranskat)abstract
- The migration of water and the influence of water content and heating rate on the rheological and structural formation of pasta dough were investigated. The dough used in the study had two different water contents, 39.5 and 41.0%, and was made using water and wheat flour. The samples, 15 x 15 x 2 cm in size, were heated from 25 to 80°C in a conventional oven at two different temperatures, 100 and 150°C, to achieve two different heating rates. During the heating the local water content was measured in the centre of the samples with a fibre-optic NIR instrument. The temperature was measured in the centre, halfway to the centre and at the surface. The rheology of the heat-treated samples was studied by means of tensile tests. Young's modulus, stress at maximum load and energy to break point were calculated. The micro structure of the samples was characterised by CLSM, confocal laser scanning microscopy, and the microstructural parameters were quantified using image analysis. The changes in rheological properties during heating were studied by means of DMA. Untreated dough samples were heated from 25 to 90°C with a heating rate of 5° C/min and a compressing oscillation of 1 Hz. The changes in phase angle δ and storage modulus E' were measured. The most important results were that no migration of water inside the pasta dough could be found. Both the water content and the heating rate affected the structural and rhelogical properties of the pasta dough. There was a maximum in E' vs. temperature, which shifted towards higher temperatures with decreasing water content. Young's modulus was affected by both the heating rate and the water content. Energy to break point and stress at maximum load were affected by the heating rate. The pore size was affected by the water content. The swelling temperature seemed to increase as the heating rate increased
|
|
| 9. |
- Thorvaldsson, K., et al.
(författare)
-
Water diffusion in bread during baking
- 1998
-
Ingår i: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 31:42193, s. 658-663
-
Tidskriftsartikel (refereegranskat)abstract
- A study of heat and water transport in bread during baking was performed. Loaves of bread were fermented twice and baked in a conventional oven at 225°C, with no forced convection, for 35 min. The local water content and two or three different temperatures were measured inside the bread during the baking process. Bread baked from wheat flour was used to investigate the mechanisms of water transport inside a loaf during baking. The water content was measured in the centre, 1 cm from the base, in the bottom crust, 1 cm under the top surface and in the top crust, using a fibre-optic NIR instrument. The temperature was measured on the bottom surface, in the centre, and 1 mm from the optic fibre. The results indicate that up to 70 ± 5°C, where a structural change is taking place, the water content in the centre changes little. However, after reaching this temperature the water content in the centre of the loaf rises due to vapour transport from the warmer regions. The water appears to be moving towards the coldest region, and not towards the geometrical centre. © 1998 Academic Press.
|
|
| 10. |
- Wendin, Karin, 1963-, et al.
(författare)
-
Fat content and homogenization effects on flavour and texture of mayonnaise with added aroma
- 1999
-
Ingår i: Lebensmittel-Wissenschaft + Technologie. - 0023-6438 .- 1096-1127. ; 32:6, s. 377-383
-
Tidskriftsartikel (refereegranskat)abstract
- The influence of fat content (700 and 820 g/kg) and homogenization on the texture and flavour of mayonnaise with added citral (semi-polar) or pyroligneous acid (polar) was investigated. The quality of mayonnaise was described by sensory descriptive profiling. Mayonnaise containing 820 g fat/kg had the highest intensity of sour smell, sour taste, thickness and fattiness. Increased fat content, from 700 to 820 g/kg, did not significantly affect the perception of smoke flavour due to pyroligneous acid, or lemon flavour due to citral. Homogenization increased sweetness and whiteness, and depressed thickness and fattiness in mayonnaises with added pyroligneous acid.
|
|
