Unit 1

Unit 1 z

Food q quality, y, stability y and safety y

Undergraduate Studies in Nutrition Food Science and Dietetics Nutrition, z

Understanding foods (origin, nutrient p patterns) p ) content,, consumption z Describing foods in term of nutrient content z Using food composition tables z Having H i th the ability bilit tto recallll ffacts t

Undergraduate Studies in Nutrition Food Science and Dietetics Nutrition, z

z

Understanding principles applied to: z Food

preparation

z Food

preservation

z Food

safety

Integrating the learned knowledge in situations relevant to NFS practice

F d attributes Food tt ib t Quality, Stability and functions Quality of foods; Sensory evaluation

Food composition p z

Macronutrients: carbohydrates y ((4 kcal/g), g), proteins (4 kcal/g), fats (9 kcal/g) g) z Micronutrients: vitamins, minerals z Water

Functions of food z

Building new tissues and repairing old ones: proteins, minerals, vitamins, water z Source of energy: carbohydrates carbohydrates, lipids lipids, proteins z Regulation of body processes: minerals minerals, vitamins, water, fiber z Part P off preventive i medicine di i z Pleasure

Sensory y evaluation z z z z z

Appearance Flavor: Odor and taste Four primary taste stimuli: salty salty, sweet, sour and bitter Taste interaction is common: Mixture of stimuli Mouthfeel: out ee Tactile act e se sensation; sat o ; texture (crunchiness)

htt // http://www.cdfin.iastate.edu/sensory2.htm dfi i t t d / 2 ht

Sensory Evaluation of Food

Factors affecting g taste z

Flavor enhancers: MSG z Temperature z Taste T t sensitivity iti it off the th individual: i di id l Concentration factor; threshold z Psychological factors in food preferences

Evaluation of foods z

Subjective: Human sensory organs (organoleptic)

Evaluation of foods z

Objective: Measurements of physical properties that relate to sensory characteristics of foods. z Appearance: pp color;; light g refracted z Flavor components: HPLC, mass spec. z Texture: viscosity, y, tenderness

A rheometer for viscosity

HPLC

A Refractometer for Color

Hidden attributes of foods z

Nutritional quality z Sanitary quality z Shelf Sh lf lif life: d decline li tto unacceptable t bl llevell z Presence of contaminants

Food Safetyy

Foodborne diseases • More than 200 known diseases are transmitted through foods • Viruses, bacteria, parasites, toxins, prions • Symptoms: mild gastroenteritis to lifethreatening syndromes

Foodborne diseases • Foodborne diseases estimate:76 million cases, 325,000 hospitalizations, and 1800 deaths in the US annually • Outbreaks are no longer traditional “church supper”, but often cross state or international lines; more difficult to track • HACCP: Food safety management

Outbreaks of Foodborne Illness in the US

Foodborne bacterial pathogens z

Salmonella z Shigella z Eschericha E h i h coli li O157:H7 z Campylobacter z Clostridium botulinum

z

Listeria Li t i monocytogenes z Staphylococcus aureus z Yersinia z Vibrio

Salmonellae • Salmonella has been known to cause illness for over 100 years (source: eggs, poultry, meat) • 1.4 million foodborne infections and 500 deaths each year in the US • Can be found in the yolk of intact eggs

Salmonellae z

Illness causes nausea nausea, vomiting vomiting, abdominal cramps, diarrhea, fever, and headache.

z

The organism is killed by heat (pasteurization temperatures) C Cross contamination t i ti should h ld b be avoided id d

z

Shigella • Shigella g was identified over 100 yyears ago. g • Shigellosis is the 3rd leading bacterial gastrointestinal disease in the U.S. • Children, especially toddlers, are the most likely to get shigellosis, common in day-care settings (S. dysenteriae).

Escherichia coli O157:H7 • E. coli O157:H7, one of hundreds of mostly harmless strains of the bacterium Escherichia coli, produces a powerful toxin and was first recognized as a human pathogen in 1982 (Shiga-like toxins). • Th The conversion i off a non-pathogen th commensall microbe i b into a pathogen changed the way harmless microorganisms are viewed. • The spinach outbreak in 2006 caused 204 illnesses and 3 deaths across the country. y

Escherichia coli O157:H7 • Most illnesses are from eating undercooked, undercooked contaminated ground beef, but also from drinking raw milk, apple juice, and after swimming in or d i ki sewage-contaminated drinking t i t d water. t ♦

Hemorrhagic colitis with little or no fever Hospitalization H Hemolytic l ti uremic i syndrome d Mortality rate

22% 6% 0.6%

E. coli O157:H7 Infection E. coli O157:H7 ingested g 3-4 days Nonbloody diarrhea, abdominal cramps 1-2 days Bloody diarrhea 94% Resolution

5 days

6%

Hemolytic Uremic Syndrome

Campylobacter • Since 1970, this pathogen has become the most common bacterial cause of diarrheal illness in the U.S. • Most illnesses are from eating contaminated poultry and poultry products products. • Relatively fragile, and sensitive to environmental stresses • Microaerophilic, i.e. requires 3 to 5% oxygen and 2 to 10% carbon dioxide for optimal growth. This is why cases occur as isolated, sporadic events, not as a part of large outbreaks • Restricted R t i t d growth th range: 30 30-47 47 d degrees C

Listeria monocytogenes • Widely distributed in the environment • Found in soil, water, vegetation, g GI of animals and humans • Can multiply at low temperature, challenging the axiom that refrigeration protects people from food pathogens • Even if growth is slow, the long shelf-life of RTE meats (60 days) presents a problem

Listeria monocytogenes • Pregnant women are 20X more likely than other adults d lt tto contract t t listeriosis li t i i (1/3 off lilisteriosis t i i cases). ) The organism is one of the few that can cross the placenta, affecting the newborns. • Listeriosis is associated with a long g incubation period (11-70 days), and the highest hospitalization and fatality rate (~30%) among foodborne pathogens. pathogens • Zero tolerance for RTE foods in the U U.S. S http://www.americanpregnancy.org/pregnancycomplications/listeria.html

Staphylococcus p y aureus z

z z

Source z Exist in air, dust, sewage, water, etc z Humans are primary source to food contamination: often present on hands hands, skin, skin or in their nose and throat z Most domestic animals Produce heat resistant enterotoxins and cause disease Symptoms: usually occur within 4 h z Vomiting z Nausea N z Cramps z Diarrhea a ea

Vibrio parahaemolyticus • The organism g inhabits coastal waters in the U.S. and Canada, is halophilic, and is associated with consumption of raw oysters particularly during the summer. • Illness (typical symptoms of food poisoning) is usuallyy self-limited and lasts 3 days.

Yersinia enterocolitica • A psychrotrophic h t hi human h pathogen, th with ith pigs being the major animal reservoir • Infection is uncommon, acquired by eating raw or undercooked pork products causing diarrhea and abdominal pain • Infants can be infected by y caretakers that handled contaminated food.

Clostridium botulinum z

A soil microorganism that is anaerobic and spore former z Germination of the spores in improperly heat treated nonacidic canned foods results in toxin production z Toxins are most potent, p causing paralysis and death of most victims.

Foods Associated with Major Bacterial Pathogens Pathogen

Foods

Camylobacter

Poultry, raw milk, untreated water

Salmonella

Eggs, poultry, meat, fresh produce, others

E. coli O157:H7

Ground beef, raw milk, fresh produce, apple cider/juice, sausage, untreated water

L. monocytogenes Ready-to-eat foods: soft cheese, deli foods, hot dog S. aureus

handling foods: meat (especially sliced meat) poultry, fish, canned mushrooms.

Parasitic pathogens

• Cryptosporidium parvum • Giardia Lamblia

Cryptosporidium yp p • Manure-contaminated water is usually the source of infection. • Cryptosporidiosis is common in child day care y ) centers ((diarrhea,, 2-4 days). • Foodborne outbreaks by C. parvum from contaminated apple cider (1993 (1993, 1996) 1996), chicken salad (1995), and green onions (1997). (1997)

Trichinella spiralis p z

Parasite in the intestines of mammals such as swine z Consumption infects humans z Cysts are destroyed at 77 C(171 F)

Toxic chemicals in foods z z z z z z z

Mycotoxins Oxalic acid (spinach, rhubarb): binds Ca Solanin (potatoes) Nitrates and nitrites Poisonous compounds in fish, mushrooms L d arsenic, Lead, i zinc, i cadmium d i Indirect food additives

Bovine Spongiform p g Encephalopathy p p y z

z z

BSE (Mad Cow Disease) affects the brain (spongelike). Cause: Prion, small protein Transmitted from animals to humans via meat consumption i (Creutzfeldt-Jakob Disease). Disease)