Considerations of critical microorganisms and indicator enzymes in connection with the pasteurization of meat products.

The first part of the work gives a general survey on critical microorganisms with regard to the pasteurization of meat products. Comparison of heat resistance of two microorganisms, under isothermal conditions, is not problematic when both survivor curves follow first-order or nth order inactivation kinetics provided that reaction orders are the same. If not so or, when survivor curves follow different types of inactivation kinetics, a more complex situation arises. It is obvious that, when z-values of the microrganisms to be compared differ considerably, z(A)≠z(B), the order of size of their heat resistance may be temperature dependent. The equivalent pasteurization time (EPT) is analogous with the sterilizing (F) value, but the chosen reference temperature is below 100°C. In the present work, z and D values of various non-sporeforming microorganisms were collected from the literature, 12D values were calculated for 60, 70 (=T(ref)) and 80°C and compared with those of `Str. faecalis-D' selected for basis of comparison. Results demonstrated that, depending on temperature, Lb. viridescens, Moraxella-Acinetobacter and some members of Lancefield D group of streptococci appear somewhat more heat resistant than `Str. faecalis-D'. Problems of applicability of the acid phosphatase in meat as a potential indicator enzyme when its z-value is not identical with the z value of the critical (`target') microorganism, are also discussed. The EPT value of the entire heat processing curve, measured in the centre of the product, was calculated by the well known Bigelow's `general method' and the above-mentioned considerations were extended to non-isothermal heating conditions.

Relationship of physically separable lean with chemical lean in pig carcasses.

This study was conducted to examine the relationships between 'physically separable lean' (carried out by the Kulmbach reference technique) and 'lean' determined by moisture or lipid analysis (called chemical lean). Five major cuts (ham, shoulder, loin, belly and neck), originating from the Hungarian cross-breed 'Hungahyb', were dissected and the weights recorded. The moisture and lipid contents of three tissue groups (lean, intermuscular fatty tissue and remainder) were determined by common laboratory methods. Adequate estimators (predictors) were then developed for the assessment of standardized or non-standardized lean content in the 'boneless cut' (without skin and subcutaneous fatty tissue). It was shown that the concept of moisture-standardized lean is analogous to that of the fat-standardized one. It appears that unbiased estimators could be obtained if the interdependences between the chemical composition (moisture or lipid content) of the lean, the 'residue' (intermuscular fatty tissue + remainder) and that of the 'boneless cut' are included in the respective equations. If these interdependences are neglected and only the corresponding means are used in these equations, biased estimates have been obtained for the standardized or non-standardized lean content in the 'boneless cut'. Difficulties arising at practical application of these concepts are also discussed in this paper.

An assessment of simple referee methods for the prediction of lean in pig carcasses.

A study was carried out in which carcass characteristics of 36 gilts were evaluated: 18 originated from the Hungarian 'Hungahyb' cross-breed, another 18, with undefined genetic background, from small private household plots. Two, rather simple substitute reference methods, called referee methods, were evaluated: measurement of carcass weight without skin and subcutaneous fat ('meat + bone'), and measurement of carcass weight without skin, subcutaneous fat and bone ('boneless meat'). Both methods gave a rather close relationship with the Kulmbach reference lean; however, removal of bone had presumably a beneficial effect on stability of prediction. The importance of preliminary information in quantitative form, giving a theoretical background for prediction equations, was presented as an example. Simple material balances could be formulated between reference lean and 'meat + bone' or 'boneless meat' content. Such material balances could not be set up with the indirect, rapid surrogate methods using mainly linear measurements (e.g. fat and muscle thickness, etc.) For this reason, as several other publications demonstrated, these latter methods seem to be more susceptible to bias than the referee methods. By determining the lipid content of the homogenised 'boneless meat' component, a 'lean' value adjusted to 3% fat content could be calculated from data which was compared to the dissected reference lean standardised also to contain 3% fat. These relationships, for several reasons discussed in this paper, were not as close as expected. So, further studies are needed to reveal these discrepancies.

Comparison of analytical methods.

A technique for comparing two analytical methods is presented in this paper. Frequently a new method, generally simpler, faster or less expensive, is compared with a reference method. The deterministic relationships between two methods, subject only to random errors, is first discussed. However, the relationship between two methods may be stochastic (non-deterministic); this problem is also discussed here. The concept of the sensitivity ratio of Mandel furnishes an appropriate basis of comparison. The use of the correlation coefficient may be completely erroneous for this purpose. Tests are presented for the significance of constants in the regression equation. Dangers in the use of stochastic relationships are strongly emphasized because of the unstable estimation of constants in the regression formula. Some systematizing principles not generally known by food scientists are presented here.

Determination of the extent of heat treatment in canned hams by use of the phosphatase test.

In determining the core temperature in canned hams by Lind's phosphatase test, residual activity depends, in general, on the integral heat treatment of the core. The concept of heat treatment equivalent is a clearer description of the phenomenon. The heat treatment equivalents were determined at constant temperatures to give a residual activity as proposed by Lind (69°C for 12-lb cans): T versus log t(69) gives a linear relationship with a z value of 5·85° C allowing the classical F(0) and z concept to be used.