The EU Chocolate Directive 2000/36/EC allows the use of the vegetable fats CBEs and CBIs up to a maximum of 5% in chocolate. Manufacturers and users must know how this has an influence on the properties of chocolate. The objective of the work reported here was to find out by systematic investigations, which effect CBEs/CBIs have on the quality parameters, hardness and heat resistance of chocolate. The influence on the hardness was tested also under extreme practical storage conditions. The quality monitoring was performed up to one year. For the determination of the heat resistance the penetrometric method was used in the temperature range 25–32 °C measuring the maximum loading force, occurring during the penetration of a cylindrical probe of 2 mm diameter with 4 mm penetration. The correlation between the average maximum loading force, relevant to the hardness of chocolate, and the temperature can be described by a linear regression at 95% confidence level. Statistical analyses (correlation analysis, residual analysis, Durban-Watson statistic) showed that it is possible to define the heat resistance of solid chocolate in the temperature range of 25–32 °C by the slope and the ordinate intercept of the regression line of the loading force vs. temperature for given parameters (composition, storage, experimental layout, etc.). For the determination of the hardness of the chocolate also the penetrometric method was used to measure the maximum loading force occurring during the penetration of a needle probe with 2 mm deformation. The hardness of the chocolate samples determined with the penetrometric method and statistical analysis (One-Way, Two-Way Analysis of Variance, Dunnett’s comparisons) is significantly dependent on the composition and storage conditions, where the storage conditions are the dominant factor. The results show that the differences in hardness between the chocolate samples with CBE/CBI and those without CBE/CBI, both stored in the cellar (cold storage), are marginal. After one week of storage the sample with CBI has nearly the same hardness as the standard sample with CB, whereas the sample with CBE was slightly softer. The differences are slightly clearer for the northern storage room (moderate temperature) and for the southern room (warm temperature). After a definite storage time the hardness of all samples increased and was in the case of the southern storage room (warm temperature) up to twice as high. The quality monitoring up to one year showed that the reason for this increase in hardness is not a special storage time but the increasing temperatures with the beginning of the warm season and the cyclic change of the temperature during day and night. So an explanation for this unexpected increase in hardness can be a thermocyclic hardening of the chocolate samples under these storage conditions.
Authors:L. Desdín García, G. Capote Rodríguez, A. Leyva Fabelo, and L. Calderín Hidalgo
This paper shows the influence of hardness on the beta backscattering coefficient from heat treated and plastic deformed carbon
steel specimens. The observed effect cannot be explained as a change in the chemical composition of the sample (or effective
atomic number). In order to explain the observed dependencies, it is necessary to take into account the structural defect
and morphological changes of the different phases.
The effect of the parameters of heat treatment on the experimental 18% maraging steels was studied using hardness tester,
optical, scanning electron and transmission electron microscopy and X-ray metallography techniques. The specimens were solution
treated at 815, 900, 1000, 1060C for periods between 1 and 4 h. After air-cooling to room temperature, a bcc martensitic
structure was obtained. The higher temperature (1060C) and longer time (4 h) of the solution treatment caused essentially
homogeneous, massive martensitic structure. The aging of the steels was studied between 240 and 480C from 1 to 41 h. As indicated
by the results, the hardness vs. aging time curves show a rapid rate of hardening at 480C while the response at 240 to 320C
is slower. The time required to reach peak hardness increases with decreasing temperature. The increase in hardness during
aging can be explained by the precipitation of hardening phases. So, it is necessary to use a high temperature solution treatment
to obtain a better alloy distribution and a tough martensitic structure, and an aging treatment at 480 C between 4 and 10
h to achieve the desired properties.
analysis (DMA), three-point bending test, and Brinell’s hardness. The influence of poly(ester) structure on cross-linking density ( ν e ), tgδ max , tgδ max height, storage modulus ( ), hardness, flexural modulus at bending ( E mod ), deflection at
martensitic matrix [ 1 , 2 ].
After solution treatment and cooling to room temperature, 17-4 PH stainless steel shows a martensitic structure but does not exhibit high hardness [ 3 ]. The ageing in the temperature range of 480–620 °C produces a
Authors:Aidin Pahlavan, Mohammad Hassan Kamani, Amir Hossein Elhamirad, Zahra Sheikholeslami, Mohammad Armin, and Hanieh Amani
canonical analysis. Their results revealed the generation of two simple models, which could simultaneously predict the bread loaf volume and crumb hardness. Ohm and Chung (1999) evaluated flour gluten, pasting, and mixogram parameters of twelve hard winter
Authors:P. Malliga, C. Alosious Gonsago, P. Sagayaraj, and A. Joseph Arul Pragasam
beyond 50 g of the applied load, hardness test could not be carried out above this load. The length of the two diagonals of the indentations were measured on the (010) and (001) planes and the Vickers microhardness number ( H v ) was computed using the