RELATIONSHIP BETWEEN INSTRUMENTAL AND SENSORY ANALYSIS OF TEXTURE AND COLOR OF POTATO CHIPS

The instrumental and sensory analysis of the texture and color of commercial potato chips were compared. The instrumental measurement was a puncture test with an Intron Universal Testing Machine, and the parameters used were fracture force, deformation and stiffness. The instrumental color quantification was a computerized video image analysis technique, and the color was expressed as L*a*b* values. Sensory evaluation of texture and color was performed by a sensory panel especially trained in evaluating potato chips. The sensory attributes were "hardness", "chewiness", "crunchiness", and "tenderness" for texture analysis, and "yellow color", "burnt aspect", "sugar colored aspect" and "transparency" for color analysis. The factor analysis of the sensory attributes indicated that texture can be divided into two principal components, one represented by "hardness", "crunchiness" and "chewiness", and the other by "tenderness" alone. The factor analysis of the color can be divided into two principal components, one including "yellow color" and "burnt aspect", and the other "sugar colored aspect" and "transparency". Discriminant analysis showed that "tenderness" and "crunchiness" could predict correctly over 90% of the data. Fracture force correlated well with all of the sensory attributes (R² > 0.76), and L* with the sensory color attributes (R² > 0.79). The "Tenderness" was the individual sensory attribute which had the highest correlation (R²= 0.95) with fracture force.     

The zero crossing variance of the smoothed random telegraph signal

The problem of determining the variance of the number of zeros in an interval (0, T) of an RC-filtered random telegraph signal is considered. We obtain an infinite series representation for the variance in terms of two parameters. When one of these parameters is an integer, the series reduces to a finite summation. Recursion relations for computation of the series terms are given, and the asymptotic behaviour of the variance is investigated. Finally, curves for the variance arc obtained for variations over four orders of magnitude of the two parameters.     

Comparative Absorption of Low Molecular Aroma Compounds into Commonly Used Food Packaging Polymer Films

Five polymer films commonly used in food packages were stored in an aqueous solution of 10 apple aroma compounds. Substances absorbed by the polymers were determined by a supercritical fluid extraction/gas chromatography method. Polypropylene absorbed most aromas, more than 2× amounts absorbed by low density polyethylene. Polyamide and polyester absorbed very small amounts of the aromas. Esters and aldehydes were absorbed much more than alcohols. Molecular size also affected absorption, larger molecules being absorbed to a greater extent than smaller ones. For most materials the absorption equilibrium was reached within a week.     

Diffusion in Heated Potato Tissues

Data to optimize nutrient retention during processing of potatoes were obtained by measuring loss of solutes (glucose, fructose, citric acid, potassium, calcium and magnesium) by diffusion into blanch water. Apparent diffusivities were calculated based on Fickian diffusion. Magnesium and calcium did not follow the Fickian approach with the same accuracy as the others. A hindrance factor (K), the ratio of apparent diffusivity in potato to a published value was used. The hindrance factor was calculated at reference temperature 25°C to separate preheating effects from the direct effect of temperature on diffusion coefficients. A mathematical model for K(T,t) was fitted to experimental data for each solute. All solutes showed a sharp decrease of hindrance factor in the region 50–60°C. These models showed, however, that heating of potato affected diffusivities of the solutes to different degrees. Ions had a limit solution retention in the tissue higher than glucose, fructose or citric acid.     

Diversion of the River Calder at Welbeck: An Engineering and Environmental Challenge

The Welbeck reclamation and landfill project (near Wakefield) is reclaiming over 1.5 km² of former aggregate and colliery workings through the creation of a new landform. This is to incorporate millions of tonnes of colliery spoil and controlled (i.e. household, trade) wastes, and to avoid the need for disposal on less suitable sites elsewhere.
The scheme is already under way, but the proposed diversion of the River Calder to one side of the site would more than double its capacity for landfill. In environmental terms, the project has been seen as the creation of a new river corridor, rather than simply the diversion of a river channel.
The paper outlines the engineering of the river diversion, which is routed for about 2 km through varied and difficult ground conditions, and gives a number of examples of the priority attached to landscape and after-use factors, and their intrinsic importance in design.     

Agriculture and dairying in the south-west of England

Within a region that is mainly agricultural, livestock production dominates and milk production accounts for nearly half the total annual value of output of £ 100 million. Over the past decade milk production has risen at a faster rate than nationally, due mainly to increased numbers of cows. There has been a marked degree of concentration in the structure of production. Here, Dorset stands out with one-third of the herds and almost two-thirds of the cows in units of 100 cows or more. Increased output has meant that profits have increased in real terms with efficiency gains in fixed costs.
Future prospects offer little hope of increased milk support prices in the EC, and the success of our milk producers will depend on expanding their share of the UK market and the extent to which fixed costs can be contained or even reduced.     

Chemical and Physical Changes in Red Hake Blocks During Frozen Storage

Storage stability of frozen red hake blocks over a 6-month period was studied under commercial conditions with processing modifications. The rate of DMA formation was significantly greater in samples dipped in polyphosphate and erythorbate compared to a reference (?90°C) or to a 5-day aged sample. There were no significant differences in the rate of decrease of extractable protein nitrogen over the 24-week period. A trained sensory panel found samples from aged fish to be generally more acceptable from a flavor and texture stand-point than the other treated samples. Mechanical shear forces tended to be higher for samples dipped in polyphosphate-erythorbate and lowest for 5-day samples among treated fillets. With proper handling red hake fillets may make a satisfactory commercial frozen block.