The slice compactness depends on several factors:
- Injections and additivation
Meat pH
Tenderizing – macerating
Massaging – tumblers
Molding
Cooking
Repressing and cooling
Demolding, pasteurizing and maturing
Slicing system
Injections and Additivation
The additivation affects yields, that is to say the water quantity you can add on a stable basis, but also the protein extraction. The additivation includes also preservatives as nitrite, that has a secondary function on red color enhancement, and antioxidants, as sodium ascorbate that also influences the color.
It is interesting to value the obtainable product for example injecting at 7% or at 20%, at equal yield. It’s easy to understand that the muscles greater swelling makes less relevant the mistake due both to injection (Which standard deviation? Which impact having the same standard deviation? Which effect on preservatives, antioxidants, flavors?) and to weight mistake during molding phase (puffed up muscles use makes simpler the best filling during molding). Until now, the industrialization of the process with multi-mold systems has prevented this technological choice, for which, however, it would be necessary to make a comparison between benefits and costs.
Meat pH
Usually the meat pH is 5.8; it’s also possible to use acidity adjusters to obtain this result or to modify it. If you add sodium citrate, you increase the pH and consequently the yields, while adding lactic acid or lactate, you improve the slice compactness but you reduce the product shelf life (this additive is not very used). The meat taste can change adding flavors but always considering the different phases of the production as cooking and maturing.
Tenderizing
Macerating Tenderizing can be done with flat blades, that better respect the product not damaging it, or with rotating blades, more invasive.
The macerating aim is to improve interaction between meat proteins and additives (starting from salt) to facilitate the protein extraction, the color homogeneity – due to cell sarcolemma break – and a minor muscle contraction – unidirectional and transversal – to make the product more isotropic when during cooking there is a reduction of the muscles volume due to weight loss.
Massaging
Massaging, together with tenderizing and injection, enables the proteins availability. Massaging – even with reduced cycles – has to last at least 24 hours to obtain proteins extraction.
Mold
The molding methods influence the seal of the slice, as well as the aesthetic result. The molding has to be careful for high quality products, that is to say with less “adhesive” addition. The molding methods conditions the slice compactness and, of course, the aesthetic result. The molding has to be more careful if you want to have the fat in the central part; in fact fat opposes to muscular bands gluing, for this reason it’s important to keep them in contact both during cooking and at its end.
Cooking
Cooking influences the final product organoleptic qualities. It’s better to use a low delta T between fluid and product (about 10°C), it doesn’t matter which cooking method you use (steam or water). In this way the product heating is more homogeneous in the section and you avoid an excessive inhomogeneity of the different muscles contraction. It’s moreover proved that working with a low delta T helps the color enhancement and uniformity. Another variable, that as delta T influences the weight loss and the cooking times, is the cooking maximum temperature which value depends also on the requested pasteurizing effect and on the contaminants you want to destroy.
Another important aspect is the thermic treatment homogeneity, this condition is easier to achieve with water cooking or using piles that facilitate steam flow, but also cooling air flow, in the 3 directions.
Re-pressing
Looking at the most known theories, re-pressing is important when the cooking weight loss is at least 4%. There is a reduction of the muscles volume when there is a weight loss and, when there isn’t an elastic element that keep them, a reduction of the contact pressure between the muscles themselves. When the product is particularly lean and with the right additives, it’s important that the in-contact muscular bands do not disconnect to have enough cohesion for slicing with acceptable thickness and productivity. When the product is a high quality one, with fat parts, it’s important to restore the contact pressure between muscles, pressing the molds again. It’s moreover necessary to make a distinction between in-bag product and thermoformed product with exudate collecting pockets.
The bag, that protrudes on the molds sides, reduces at the minimum the exudate way and the “blockages” risk, so, normally, it’s not strictly necessary to re-press the molds if the weight loss is small.
The thermoformed product, with pockets on the heads, needs a longer way to collect the exudate and it has more obstruction risks in the pockets connecting channels; this makes re-pressing necessary because the liquid will stagnate at least over the product.
In all the cases a small weight loss and the absence of elastic compensation will cause an irregular distribution over the bar of the exudate, with local sections variations and a worse aesthetic result.
In any case, the slicing yields are better when the product is more compact.
Cooling
Another important aspect, above all with big section products, is to make a fast cooling. A fast cooling influences yields and shelf-life (that increases) quality in slicing. When water cooking is used, the cooling is made first with well water, when the delta T is high, then with ice water (1–2°C), properly recirculated, in a way to compensate for the final phase low delta T (about 5°C) with a better exchange coefficient. It will be easy to have a homogeneous cooling of the treated pile. When steam cooking is used, the cooling is made first with shower and then in a ventilated cold room or in a shock freezer. In both cases, but mainly in the first one, it’s important to use piles that facilitate the air flow in all the 3 directions. Water is sprayed in air at -15°C -20°C in the shock freezers, using strong ventilation, in a way to have ice on all the molds surfaces. In this way the latent heat, due to the phase changing, is employed. It’s important to point out that it should be possible a too high local cooling, with very low temperature, but only till the moment the ice is not on the mold (it has a sort of buffer effect) and anyway it will cause only a surface damage that won’t influence the slicing performances.
Demolding, pasteurizing, maturing
The demolding operations, that is to say the products extraction from the molds, are different in presence of exudate collected in pockets or in parts of the packaging. After demolding you can proceed in different ways, for example piercing the parts with exudate in a way to disperse the liquid/jelly and put the product in contact with the environment. This technological approach minimizes the gas (formation during cooking process) formation/discharge, putting the product in contact with the atmosphere for enough time. It’s clear that this procedure increases the risk of product (that won’t be pasteurized) contamination and, consequently, the shelf life reduction. Another modality, that can be used with thermoformed product, establishes the separation of the exudate pockets and the thermo-welding of the part containing the product not to put it in contact with atmosphere. The advantages of this method, if it is enough reliable, are the exudate (liquid reach of proteins that can be sold to cosmetics industry and, above all, to pet food industry) collection and the possibility to proceed to maturing the product. As an alternative you can completely remove the cooking packaging, trim the product removing jelly parts on it; package again the product and then pasteurize it. This process best guarantees the product quality, but it’s, of course, expensive. The product maturing, that is to say keeping it, anyway under-vacuum packaged, for a certain period at a temperature between -1°C and 0°C, has the aim to level the humidity, the color, the flavor and to increase the product compactness to have the best slicing performances. A long maturing (it can reach even 2 months) needs room and financial assets, but it ensures a faster slicing speed.
Slicing modality
The slicing yield is related to the absence (or minimization) of scraps. It’s important to have long and compact products to maximize the productivity of the slicing plants that are very expensive, even in maintenance. Normally the cooked products temperature for slicing hasn’t to go under -5°C, to avoid product crumbling during cutting. The goal is to reach 600 slices/hour, this speed can be easily obtained if the product is “gummy”. The “gummy” quality permits to have thin slices, in Italy between 0,7 and 1 mm. The “gummy” quality has to be homogeneous along all the bar to slice. This result can be obtained with molds with uniform pressure distribution and without structural deformation.
In brief it’s important to intervene on:
- Molding modalities
Availability of a mold that can adapt itself to the product volume changing
Availability of a mold stiff enough to assure the uniform contact pressure between the muscular bands
Prolonged product maturing.