FOOD ADDITIVESFOOD ADDITIVES4TH YEAR LECTURE

IST SEMESTER

1FOURTH YEAR LECTURE Prof Kang'ethe

IntroductionIntroductionProtection from health and

economic deceptionIndividual consumers unable to

protect themselves hence responsibility rests on industry and Government

Time when adding chemicals to food not necessary but prehistoric man added when he smoked food

2FOURTH YEAR LECTURE Prof Kang'ethe

DefinitionDefinitionWHO/FAO – non nutritious substances

added intentionally, in small quantities to improve appearance, flavor, texture and storage properties. Failed to include nutritional supplements and non intentional additives

Codex alimentarius – any substance, including those of microbial origin not normally eaten as food stuff proper but use causes substance or metabolites become constituent of food proper

3FOURTH YEAR LECTURE Prof Kang'ethe

Classification of additivesClassification of additivesIntentional and non intentionalNon intentional – have no

intended function become part of food in the phase of production or handling e.g pesticide, antibiotics, packaging materials & lubricants

4FOURTH YEAR LECTURE Prof Kang'ethe

Why Food additives?Why Food additives?Food production separated from areas of

population concentration – preservativesAdded for functional properties – color,

flavor, texture, nutritional supplements etc

Convenience foods – foods whose preparation labor removed from household to processor or manufacturer. eg flour, can of beans or soups, cake mix, githeri, chapos, pisas, etc

5FOURTH YEAR LECTURE Prof Kang'ethe

Requirements for food Requirements for food additivesadditivesAdditive is safe in food at intended levelPerforms intended functionNot used to deceive customerNOT cover faulty manufacturing practicesDoes not cause substantial reduction in

food nutritional valueNot used where GMP can achieve the

sameMethod of analysis exists to police its use

6FOURTH YEAR LECTURE Prof Kang'ethe

PreservativesPreservativesAre antimicrobial and antioxidantsPrevent microbial spoilage – sugar,

salt, nitrates etcSodium benzoates - active at pH 2.5-

4.0 mostly against yeast and moulds. Permitted level 0.2 -1.25%

Benzoic acid and its salts – against moulds and yeast 0.03=0.1%

Sorbates – pH 6.5, moulds and yeasts 0.03 -0.1%

7FOURTH YEAR LECTURE Prof Kang'ethe

PreservativesPreservativesPropionates – pH 5.0 – 6.0, used in

baked foods mainly against moulds and rope (B. mesentericus)

Sulphur dioxide and sulfites – Fruits pulp juices. Prevent enzymic and non enzymic browning. Preserve vit C, destroy thiamin, limits 500ppm

Acetates – Act in low pH foods –moulds and yeast

8FOURTH YEAR LECTURE Prof Kang'ethe

AdditivesAdditivesGas SterilantsEthylene oxide gas above 10.7oC,

propylene oxide 35oC. Used as fumigants

• AntibioticsThose not used in medicine. OTC and

CTC used in fish (7ppm). Nicin used in cheese while subtilin ,tylosin, nystatin and pimaracin against fungal.

9FOURTH YEAR LECTURE Prof Kang'ethe

AdditivesAdditivesAntioxidantsUsed to stabilize foods against oxidative

deterioration. Natural occurring and synthetic. Butylated hydroxytoluene (BHT,) BHA, Propyl gallate, Lecithin and tocopherols

• SequestrantsAre stabilizers. React with metals hence

synergists to antioxidantsSurface active agentsPlay a role in growth processes of foods and

assist metabolism converting them into sources of energy

10FOURTH YEAR LECTURE Prof Kang'ethe

Naturally occurring lecithin, lanolin, bile salts, cholesterol.

Stabilizers and thicknersUsed to give body and texture –

agar agar, gelatin and cellulose. Mainly used in confectionery.

• Food colors – vary color of foods, Red G

11FOURTH YEAR LECTURE Prof Kang'ethe

RESIDUESRESIDUESNon intentionalAntibiotics and PesticidesAntibioticsTreatment or indiscriminate

treatment of animal diseases. Failure to observe withdrawal periods.

Problems of antibiotic residuesAllergy to sensitized individualsProblem in manufacturing – milk

12FOURTH YEAR LECTURE Prof Kang'ethe

RESIDUESRESIDUESDrug resistant strainsTreatment drugsCarcinogensMilk – 13% in milk from rural and

urban Nakuru and Kiambu, 1% in urban milk in Dagoretti, Nairobi mostly penicillin type

Pesticides in milk, meat, eggs and human milk – agricultural activities. Poor handling procedures – non target hence affect environment

13FOURTH YEAR LECTURE Prof Kang'ethe

Microbiological CriteriaMicrobiological CriteriaUsed to designate the foods safetyThese fall into two categories –

mandatory and advisory.Mandatory usually contains limits for

pathogens of public health importance. Limits for non pathogens may also be set.

Advisory is a microbiological end product specification intended to increase assurance that guidelines have been met

14FOURTH YEAR LECTURE Prof Kang'ethe

Microbiological CriteriaMicrobiological CriteriaStandard is considered part of a law

that has regulatory enforcement by agency having jurisdiction (KEBS)

Criterion consists of statement of microorganism of concern, analytical methods for detection and quantification, sampling plan when and where samples can be taken, limits considered appropriate and number of units that should confirm

15FOURTH YEAR LECTURE Prof Kang'ethe

Microbiological Criteria – Microbiological Criteria – Sampling PlansSampling Plans

Criteria for acceptance based on appropriate examination of number of samples units by specified methods

Two class plan and three class plan◦Two class consists of n, c and m. ◦n is the number of units that must be

examined◦c is the maximum acceptable number

that may exceed the criterion◦m is maximum number or level above

this either marginally acceptable or unacceptable

16FOURTH YEAR LECTURE Prof Kang'ethe

Microbiological Criteria-Microbiological Criteria-Sampling plansSampling plans

Class three criterion has all the three levels in class two plus M

M is a quantity used to separate marginally acceptable from unacceptable quality foods

n=5, c = 0, 2 and m= 102 five units examined, no more than 2 exceed 102

n=5, c=2 m=102; M= 103 2 units could exceed 102 but if any exceed 103 lot unacceptable

Applied in conjunction with a comprehensive programm like HACCP.

17FOURTH YEAR LECTURE Prof Kang'ethe