Long Exam 1 (Topic 1-3)

• 1600s: Antonie van Leeuwenhoek discovered the presence of microorganisms.
• The era, prior to the establishment of bacteriology as a science, may be designated as the Pre-scientific era.
• During the pre-scientific era, bacteriology (the study of microorganisms or bacteria) is not yet established.
• The Pre-scientific era can be further divided to: Food-gathering period and Food-producing period.
• Food-gathering period: humans were presumably carnivorous, with plants coming into their diet the later part of this period. This is also the period where foods were first cooked. This dates back 10000 years ago.
• • Food-producing period: dates back from 10000 years ago up to the present. It is presumed that the problems of food spoilage and food poisoning were encountered in this period. In this period, humans began to learn how to preserve, prepare, and store food.
• 6000 BC: Spoilage of prepared foods was recorded.
• 5000 BC: First evidence of beer manufacturing has been traced to ancient babylonia. The art of cereal cookery, food storage, and brewing were recorded.
• • 1200-3500 BC: First to make dairy products such as milk, butter, and cheese. The production of dairy products were pioneered by the Sumerians. Sumerians were the first greek livestock breeders and dairy men. Salt is used for preservation. Fermented sausages were prepared. 
• 1000 BC: The Romans excelled in the preservation of meats other than beef, and used snow to pack prawns and other perishables. During this era, despite these advancements, they still don’t have knowledge of how spoilage works.
• 943-1100 AD: Ergot poisoning (caused by Claviceps purpurea) caused many deaths during the Middle Ages. Caused around 40,000 deaths just in France alone since they still don’t understand the connection of microbes in their foods that time.
• 1156-1276: Meat butchers were mentioned. Swiss were concerned with marketable and nonmarketable meat. This marketability is connected with food quality. Slaughter and inspection order for the public abattoirs in Augsburg.
• 13th Century: Knowledge of the relationship between food quality and microorganism was not known.
• 1658: Kircher was probably the first person to describe the relationship between microorganisms and food. Kircher examined decaying bodies, meat, milk, and other substances. He described what he observed as “worms.” At that time, Kircher’s description lacked precision, and was not accepted by the scientific community and the general public.
• 1680: discovery of microscope. A. Leeuwenhoek first to observe yeast cells. He was also the one to first describe bacteria and protozoans. Spontaneous generation theory evolved after this discovery due to the curiosity of many scientists. They first termed what they saw as “animalcules” or tiny things. The theory states that living organisms can come from nonliving organisms.
• 1668-1765: Two Italian scientists; Francesco Redi and Lazzaro Spallanzani performed experiments to disprove the Spontaneous Generation Theory.
• Francesco Redi performed a meat experiment in 1668. This meat experiment consisted of originally two set-ups, which later on became three.
• First set-up, both containers have meat placed inside. 

  1. Containers were left open.
  2. Flies swarmed the meat and laid eggs.
  3. Maggots developed onto the meat product.
• Second set-up, both containers have meat placed inside. 

  1. Containers were tightly sealed. 
  2. Flies were not able to enter the container and lay their eggs. Maggots did not develop.  No living organism detected.
• Antagonists scientists stated that Spontaneous Generation Theory is only observed or will only happen if oxygen is present. Thus, in a tightly sealed container where oxygen can’t pass through, Spontaneous Generation Theory will not be observed. This led to the third set-up.

  
  

  1. Containers were covered with cloth netting, allowing oxygen to pass through.
  2. The container is still accessible to flies, and laid their eggs on the surface of the cloth netting.
  3. Maggots did not develop on the meat.
• CONCLUSION by Francesco Redi: Meat alone was not able to generate maggots.
• Antagonist scientists replied that “Perhaps spontaneous generation cannot occur with larger creatures (eg. Maggots) but can occur in microscopic organisms”
• To further support Spontaneous Generation Theory, John Needham did an experiment in 1745.
• 1. John Needham placed nutrient broth in a flask, heated it, and sealed it. 
  2. The nutrient broth was spoiled after some time. 
  3. CONCLUSION by John Needham: Microorganisms developed spontaneously from the fluids. 
  4. Needham stated that the spoilage was caused by a reaction. And this reaction was due to the presence of microorganisms that were not visible to the naked eye. 
  5. HOWEVER, Lazzaro Spallanzani debunked Needham’s conclusion, stating that there is a mistake in Needham’s methodology. 
• • Spallanzani did the same experiment in 1765, but altered the order of the methodology. 
  • Spallanzani placed nutrient broth in a flask.
  • He sealed it first, then heated it. 
  • The nutrient broth was not spoiled after some time.
  • CONCLUSION by Spallanzani: Spontaneous generation did not occur. 
• • 1795: The debate regarding the Spontaneous Generation Theory is still not finished. Nicolas Appert did the first food preservation by canning (brewery). His development was the beginning of the canning method or appertisation.
• • 1837: Louis Pasteur was the first person to appreciate and understand the presence and role of microorganisms in food; Demonstrated souring of milk
  • After 2 centuries of debate about Spontaneous Generation Theory, Louis Pasteur ended the debate. 
• 1860: Louis Pasteur demonstrated the use of heat to destroy microorganisms in wine and beer. This process is now known as pasteurization.
• In this pasteurization, Pasteur was able to understand the importance of microorganisms in the brewing of wine and beer.  Since in brewing, microorganisms are needed as starter culture, but at some point, you have to deactivate these microorganisms to prevent the beverage from spoiling.
• Louis Pasteur experiment in 1861.

  1. Pasteur demonstrated that microorganisms are present in the air and can contaminate sterile solutions. He emphasized that air itself is not able to create microorganisms. 
  2. He placed broth inside a flask, sterilized it through heating, and allowed it to cool down.
  3. The flask has an S-neck, that allows bacteria and dust from air to settle in the bend. 
  4. He stored the flask for years, and the broth stayed sterile indefinitely. 
  5. He tilted the flask so as to allow the sterile broth to come into contact with the bacteria and dust from the air (contaminated part).
• Pasteur reasoned that microorganisms in the air were the agents responsible for contaminating non-living matter such as the broth in Needham's flask. 

  
  

  Pasteur demonstrated that microbes can be killed by heat and that methods can be devised to block the access of airborne microorganisms to nutrient environments. This became the basis of Aseptic Technique. 
• CONCLUSION by Pasteur: Microorganisms cannot originate from mystical forces/ from non-living materials.

  
  

  Other Conclusions by Pasteur: Microorganisms can be present in non-living matter (solids, liquids, air)

  1. It can be present but it cannot be born from non-living materials. 
• Food microbiology is the interconnection of Food, Microbiology, and Consumers.
• Although the primary role of microorganisms is often destructive as they cause food spoilage and foodborne diseases, the primary role is actually not to destroy but to self-perpetuate, just like humans.
• The primary role of microorganisms is more of self-preservation, because they do anything to keep themselves alive.
• On the other hand, we can’t neglect the fact that microorganisms have an important role in food production. These are important in the food industry as they are used to produce food items, ingredients, and processing aids. And they are widely used in the industry of Food fermentation. 
• Researchers and scientists develop conventional and novel methods for microbial analysis of food. This is done in order for us to analyze how to balance the beneficial and deleterious effects of microorganisms.
• Microbial analysis of food aids in keeping the food safe (Food hygiene) while keeping its quality (quality control).
• These scientific methods help in setting standards and controls, and come up with appropriate legislations (Food legislations).
• Food legislations are designed to protect consumers from food that can be injurious to one’s health (Laws on Food safety).  These are also designed to protect us from misleading information (laws on Food labeling and advertising).