1types of sausages:
fresh
cured
fermented
2main public health hazards
fresh: faecal path
cured: faecal path, salt tolerant bacteria
fermented: trichinella. salmonella
3what hurdles do cured sausages haev
High salt content. Note: nitrites/nitrates are used in these sausages only for colour and not for the control of Cl. botulinum, as this pathogen cannot grow in these sausages (too much oxygen!)
4hurdles for fermented sausages
High salt; Low aW; Low pH;
5roles of nitrates
a. To prevent the discolouration of the products into greyrown and maintain a red/pink colour instead b. To prevent the germination and growth of Clostridium botulinum (IMPORTANT: nitrates/nitrites have minimal effect on the common faecal pathogens!)
6can fresh sausages contain high amounts of nitrates and be safe at room temp
No. Nitrites/nitrates are effective only against anaerobes, e.g. Cl. botulinum. They don’t have any effect against the other, more common pathogens, like Salmonella etc.
7ingredients of fresh sausage
Minced meat/fat, salt and spices. No nitrates/nitrites.
8ingredients of cured/ cooked sausages
Minced meat/fat, salt, spices and nitrates/nitrites.
9dry and fermented sausages
Minced meat/fat, salt, spices, nitrates/nitrites and sugars.
10purpose of canning
- To make foods safe from Clostridium botulinum - To extend the shelf life of foods without the need of refrigeration
11min required log reduction for c botulism
12 D
12C. botulinum is ubiquitous but in low numbers. A can of food before processing is not expected to have more than 1,000 (i.e. 103 ) cells. What does a heat treatment of 12D mean in practice for these cans?
A 12log reduction application in this example means that that the initial population of 103 (or 3 log) bacteria will be reduced by 10-12 times (or 12 log), resulting in a final population of 10-9 (or -9log) cells. In practice this means that one in 109 cans may contain one live cell of the pathogen
13Which canned foods that have not been heated to levels that eliminate C. botulinum can be free from botulism
pH at or below 4.6 (or according to some sources 4.8) is a limiting factor for the growth of C. botulinum. All cans that contain food at or below pH 4.6 are safe from this pathogen