Some foods are considered more likely to contain microbes; these foods are considered potentially hazardous foods. If you were at an all-school or community picnic and there was an unlimited supply of food, more than you could possibly eat, what foods would you avoid or select to eat? What are some categories of foods that might be considered hazardous? Under-cooked or foods that you eat raw are more dangerous that foods that have been cooked. Raw foods should always be washed before eating. Another group of foods might be "bland foods"-- foods with a pH around 7. Since most microbes are neutrophiles, any food with a pH of 7 will support a great variety of microbes. Now thinking about that all-school picnic, do you select the tun/pea/macaroni hotdish or the hamburger/tomato/macaroni hotdish? The tomato hotdish would be more acidic and less likely to support microbial growth. Combination foods that have a binder to mix all the foods are a potentially hazardous food. Each ingredient in the food has its own normal flora, so a combination food may have a variety of microbes. I call subs and pizza "intimately handled" foods. You roll our the crust, grate or chop the cheese, cut the tomatoes, and place each slice of pepperoni on the pizza or sub. You have handled each ingredient and potentially contaminated the food. Chopped foods like hamburger are potentially more dangerous than steak. Why? Ground foods have more surface area exposed to the air and potential microbes--plus the grinder might be contaminated.. Foods intentially prepared in advance or served as left-overs have the potential to have lots of microbes. Sometimes the weekend is the day to prepare a big roast with potatoes, onions, and carrots, or a large turkey with dressing, or a big pot of stew so you have food all week. Taking the food from the refrigerator to room temperature to serve allows the temperature of the food to increase and the growth of microbes is encouraged. By the middle of the week, the middle of the food may contain numerous microbes.