First, we have to know which kind of food we are dealing with, this gives us more information about the microbes that can attack/grow in this food. Then the intrinsic factors to be manipulated includes:

1. Water activity/ water contents.

2. Food matrix (food components/nutrients)

3. Redox potential

4. Antimicrobials

5. Acidity (pH)

6. Presence of biological structures

Going into details

1. Water activity/water content

As we know, water is a good medium for many reactions to take place. Availability of water in foods create a good medium for the microbial growth. The more the water content in foods, the more perishable it is. Through the water content, the food is classified into 3 classes: a) perishable foods with high water actibity b) semi-perishable foods with intermediate water activity and c) non perishable foods with low water activity. When you decrease the water content in the food, you decrease also the microbial growth in your food because the microorganisms can undergo an osmotic shock, making them to shrink and even die. The knowledge of microorganisms that can attack the food is needed. You need to know whether it is a bacteria, yeasts, or molds...

2. Presence of nutrients (food matrix)

Like human, microorganisms needs nutrients like carbohydrates, proteins, fats, and many others to maintain their metabolisms and grpwth. Depending on which nutrients present in the food, there are specific microorganisms that are going to attack this food. This give you an idea of by which conditions you can treat your food to ensure the inhibition of microbial growth in your food.

3. Redox potential

Highly oxidised food products will have positivi redox potential values and highly reduced food products will have negative redox potential values. Aerobic microorganisms need positive redox potential values to grow while anaerobic microorganisms need negative redox potential values to grow.

4. Presence of antimicrobials.

Somefoods contain organic acids naturally which inhibit or prevent some microbial growth whole others do not have these acids. If acidulands is added, to these foods without high acidity i.e low pH, there is an increase of acidity. This is an example of one of the antimicrobials that are in foods...that can be manipulated to reach the safety of the foods.

5. pH

Foods can be classified according to their acidity. Low acidic food, moderate and high acidic foods and so on. Through fermentation, or by adding some organic acids as said above...we can increase the acidity of the food making it more stable.

6. Some biological structure.

There some biological structures in some foods like shell of nuts, eggs and so on these structures also help in preventing the entry of microorganisms in the foods but for me I don't know how they are intrinsic...

Intrinsic factors like pH, moisture content, and nutrient availability can be manipulated to inhibit microbial growth. For example, adjusting pH levels or reducing moisture content can create an environment that is less conducive to microbial proliferation. Additionally, modifying packaging, storage temperature, and atmosphere composition can help control microbial growth in food.

Intrinsic factors such pH, moisture content, and nutrient availability can be manipulated to enhance food safety by reducing microbial growth. For example, lowering the pH of food through acidification will help inhibit bacterial growth, while controlling moisture levels will limit microbial multiplication. Additionally, adding preservatives to food or adjusting nutrient availability by reducing water activity can hinder microbial growth, ensuring safer food products.