About Bacteria in Food
Humans have used bacterial fermentation for thousands of years, long before anyone knew bacteria existed. Microbes can turn milk into yogurt, help make cheese, acidify vegetables, and create flavors in many traditional foods. Other bacteria can spoil food or cause illness, so food microbiology also includes safety.
Fermentation
Microorganisms transform food molecules into new compounds.
Learn MoreYogurt
Yogurt is made using specific bacterial starter cultures.
Learn MoreCheese
Bacteria help acidify milk and develop flavors during cheesemaking.
Learn MoreFermented Vegetables
Lactic acid bacteria help make sauerkraut, kimchi, and some pickles.
Learn MoreProbiotics
Some foods contain live microorganisms marketed for health benefits.
Learn MoreFood Spoilage
Bacteria are one of several causes of food spoilage.
Learn MoreTemperature Matters
Microbial growth rate changes with temperature.
Learn MoreFood Microbiology
Food scientists study both useful and harmful microorganisms.
Learn MoreFermentation
Lactic acid bacteria convert sugars into lactic acid. The falling pH changes flavor and texture and can make the environment less suitable for many spoilage organisms.
Yogurt
Traditional yogurt cultures commonly include Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus. They work together to acidify milk and create characteristic flavor and texture.
Cheese
Different cheeses use different cultures and aging conditions. Bacteria can influence acidity, aroma, texture, holes, rind development, and how proteins and fats change during ripening.
Fermented Vegetables
Salt and low-oxygen conditions encourage useful fermentation communities. As acid builds, the microbial community changes. Recipes differ around the world and can involve additional microbes such as yeasts.
Probiotics
The word probiotic has a specific scientific meaning: a live microorganism that provides a health benefit when given in adequate amounts. Benefits are strain-specific, so not every fermented food or bacterial culture qualifies automatically.
Food Spoilage
Microbes can create odors, slime, gas, color changes, or texture changes. Yeasts and molds can also spoil food. A food can sometimes contain harmful microbes without obvious spoilage, so appearance alone is not a complete safety test.
Temperature Matters
Refrigeration slows the growth of many bacteria but does not sterilize food. Cooking can kill many microorganisms when appropriate temperatures are reached. Food-safety agencies publish specific guidance for storage and cooking.
Food Microbiology
Laboratories test products, identify contamination, improve fermentation cultures, study shelf life, and design processing methods that protect safety while preserving quality.