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:O. Velasco-González, S. Echavarría-Almeida, A. Pajarito, and E. San Martín-Martinez
Velasco-González, O.H., Bernal, L.I. & Azteinza, B.G.
(1991): Bean separation of different grades of hardness.
8th Word Congress of Food Science and Technology
. 29 Sep–4 October, Toronto, Canada, pp. 177
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.
Development of biomineralizing techniques requires new or borrowed methods, as well as instruments for the evaluation of the efficacy of the biomineralization. The aim of the research was to evaluate the appropriateness of two existing techniques for measuring the surface hardness and material loss of microbially treated porous limestone surfaces. Measurements were done with Duroscope, and with the peeling-tape method. The techniques were tested in a comparison trial, where different bio-based curing compounds were applied on porous Sóskút limestone slabs. Two of the bio-based, and the conventional compounds show higher development in the surface rebound values (86.67 to 201.1%) and higher decrease in material-loss (−39.5 to 96.3%) compared to the control specimen. Through statistical analysis of statistical samples with a high number of results, the suitability of the techniques was evaluated.
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.
Many wheat species and cultivars, independent of genetic markers of hardness, can produce grain with a vitreous, mealy or mixed appearance. This study analyzed selected chemical and physical differences between kernels with a vitreous and mealy appearance, hand-picked from grain of four winter wheat cultivars cultivated in Poland. Separated fractions were examined for protein content and composition, friabilin presence, carotenoids and total phenolic compounds content, specific kernel density, hardness, as well as kernel surface color. It was found that the ratio of vitreous kernels in the cultivars ranged from 39.18% to 76.28%. Vitreous kernels were darker, slightly heavier and harder than mealy kernels. Additionally, these kernels were more abundant in proteins (an average increase of 2.13%, with variation among cultivars from 0.71% to 2.89%). This type of kernels was also richer in phenolic compounds (on average by 4.02%) and less abundant in carotenoids (on average by 4.53%). Mealy (softer) kernels fractured to a finer flour.
Authors:É. Varga-Visi, B. Toxanbayeva, G. Andrássyné Baka, and R. Romvári
The fat content of Bologna-type turkey sausages was partially replaced with pea fiber or potato starch. Textural properties of full fat turkey sausage were mainly restored in sausages when fat was partially replaced with some levels of pea fiber (0.6, 1.2%) or potato starch (1.9%). Authors observed significant correlation (P<0.01) between instrumentally measured values of hardness and chewiness and sensory ratings of low fat sausages.
A new objective texture test method was developed and compared with the
goose liver manual grading system. The whole fatty goose livers were purchased
from Bábolna Holdings and were examined at two stages: in the preliminary test
three times 3 pieces were taken, while in the main test five times 22 pieces.
All of them were examined both at a pre-cooled stage and after a 24-hour
storage on ice. The texture analyses were made by QTS 25 texture test system
immediately after the manual grading. A special probe with three needles was
developed for the Texture Analyser. Most of the texture parameters correlated
significantly with the liver grades, as shown by statistical evaluation of the
data. The best quality assessment was made by a binary equation where the hardness
value and the mass of the product were the independent variables.