Both the statements are true. This is because some enzymes like peroxide get reactivated after heating.

All of the mentioned food items have enzyme peroxide in them. Vinegar added to pickles increases the heat destruction of peroxide. Hence the enzyme gets killed and no biological activity is present. As a result it does not get deteriorated. Whereas in the other cases, sugar in pears and salt in tomato resists heat and protects peroxide.

Longer heating time is required to kill spores as the concentration of sugar increases. Both sugar and salt help in preserving food.

In a thermocouple, two wires are of different materials and a voltage difference is created due to the conduction of each material at the juncture and this gives us the difference in temperature in both metals and hence the temperature of the liquid. All points inside a container do not heat up at steady rates. The zone of slowest heating in a container is called a cold point of a container.

In syrup packed with sweet potatoes, the heat transfer is through convection initially. But when the starch particles from the solids separate, they retard the heat transfer.

Destruction of the phosphate based enzyme in milk after heat treatment is an indication that several pathogens have been destroyed. Destruction of the peroxide based enzyme in fruits after heat treatment is an indication that several pathogens have been destroyed.

It difficult to kill yeast in a salad dressing because the bacteria get stuck in the oil phase.

All of the mentioned statements with respect to activation energy are true.

Broths and thin soup with loads of starch in it. The starch in these solids which separates or leaches out retards heat. Hence, in chopped vegetables with high starch content packed with free liquid, the leached starch retards heat transfer.

Sterilization value of steam depends largely on the transfer of heat of vaporization to the object upon which it condenses. Canned food items which heat up by convection heat up faster than those by conduction. This is because heat transfer by convection (actual movement of molecules) is faster than heat transfer by conduction (simple molecular vibration).