Temperature control is an essential factor to guarantee the absence of microbial colonization.
The danger zone is the temperature interval the most favorable for the growth of micro-organisms, pathogenic or not, that can affect, among others, the food organoleptic and physico-chemical properties.
This microbial growth is responsible for food poisoning that can seriously affect consumer health. It can also cause serious consequences and result in death.
(French food security led-direction)
Food preparations intended to be cold stored, must be quickly chilled after their last thermic treatment or, in absence of thermic treatment, after their last preparation stage.
The professional must prove that the fast chilled product core came from +63°C to +10°C in less than 2 hours, or justify by his analysis about the dangers of the values applied if differents from the ones defined in the regulation.
Generally speaking, all meat preparations not heat bonding treated must undergo a blast chilling.
Product's preserving method between its production and its consumption involving to lower quickly its temperature immediatly after its production (up to less than + 10° C in less than 2 hours).
Then it is cold stored (between 0 and +2° C) and moved to warm temperature just before its consumption.
The deep freezing of pre-cooked meals is done so that their temperature does not stay for more than 4h30 long between a value range of +65°C and -18°C.
The deep freezing is a fast freezing which avoids product's degradation due to macro-crystallization : water inside the product cells forming in big crystals after their enveloppe burst.
Meat blast chilling / slow chilling microscopic views : 27 X magnification
Raw hamburgers frozen at – 18°C
To understand the interest of blast chilling, it is necessary to view the product at the cellular scale.
Microscopic views above allow to notice the impact of slow chilling (right picture) on product cells. The cells envelope is for the most part torned causing a conglomeration of free liquid. This effect is called macro cristallization because of the cristal sizes induced by a slow chilling. On the contrary, a freezing (blast chilling) allows to the cells envelop and the product (left picture).
Deep freezing effects are particularely visible after the product's thawing : Above pictures of thawed shrimps, on the left deep freezed sample, on the right slow freezed sample.
After thawing, the deep freezed shrimps have preserved their volume and rejected a few quantity of water, on the contrary, the slow freezed shrimps have lost their original volume and a large quantity of water. To be noticed : a slow freezing leads to organoleptic degradation, taste denaturalization and stifness of the product.