The discussion of factor that influencing microbial growth in food can be categorized into 2 part: intrinsic factor and extrinsic factor.
In word, Extrinsic is something that will influence the growth externally and in opposite internal is something that influence the growth directly. (This definition is the way I understand for this word, so you might have some other definition by your own).
The first thing to discuss is the intrinsic factor. The intrinsic factor that influence the microbial growth in food are pH value, water activity (Aw), Redox potential (Eh), nutrients and inhibitory subtances.
pH value is a measure scale in detemine the acidity and basicity of dilution aqueous solution. Chemically said, it is to measure free H+ in the system where it is expressed as pH= -log[H3O+].
Since the discussion is on food microbiology, the discussion will not discuss on how to calculate all those pH value so if any of you still don't know... just google it.
In general, neutral pH (~pH7) is suitable for most bacterial growth and acidic pH is a suitable pH for yeast and mould. The spoilage in acidic food is longer than neutral pH food.
Fruits is basically an acidic food where mainly acid can be found are tartaric acid, acetic acid and malic acid. Hence yeast and mould are suspect for fruit spoilage.
Vegetable is a low buffer foods where it has low acid and moderate pH range (pH4-6.5). Hence it is susceptible on spoilage of bacteria and some mould.
In meat, the pH is almost neutral. Hence, bacteria is the main cause of spoilage of this type of foods when it was related to pH value.
In word, Extrinsic is something that will influence the growth externally and in opposite internal is something that influence the growth directly. (This definition is the way I understand for this word, so you might have some other definition by your own).
The first thing to discuss is the intrinsic factor. The intrinsic factor that influence the microbial growth in food are pH value, water activity (Aw), Redox potential (Eh), nutrients and inhibitory subtances.
pH value is a measure scale in detemine the acidity and basicity of dilution aqueous solution. Chemically said, it is to measure free H+ in the system where it is expressed as pH= -log[H3O+].
Since the discussion is on food microbiology, the discussion will not discuss on how to calculate all those pH value so if any of you still don't know... just google it.
In general, neutral pH (~pH7) is suitable for most bacterial growth and acidic pH is a suitable pH for yeast and mould. The spoilage in acidic food is longer than neutral pH food.
Fruits is basically an acidic food where mainly acid can be found are tartaric acid, acetic acid and malic acid. Hence yeast and mould are suspect for fruit spoilage.
Vegetable is a low buffer foods where it has low acid and moderate pH range (pH4-6.5). Hence it is susceptible on spoilage of bacteria and some mould.
In meat, the pH is almost neutral. Hence, bacteria is the main cause of spoilage of this type of foods when it was related to pH value.
OK, cukuplah kot... haahahaha malas
-RedBloodCell-
1 comments:
alaa..wat la lg. bgus la ko wat mcm ni. aku xabis stdy lg. hehehehe..wat y bab last2 tu. batch fermentation n all. pleeaseeeeeee~ =p
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