MAP

modified atmosphere packaging

enclosure of food products in gas barrier materials in which the gaseous environment has been changed to slow respiration rates, reduce growth, retard enzymatic spoilage

purpose of MAP

extend shelf life by lengthening freshness

CAP

controlled atmosphere packaging: replacement of air with a gas mixture and maintain continuous control of atmosphere

where - CAP

warehouse

MAP method

change atmosphere by evacuating and backflushing with gas - increase inside pressure

VP

vacuum packaging - removal of air from package and hermetically sealing - pressure inside is lower than outside

film required for VP

high barrier film

CO2

bacteriostatic and fungistatic, inhibits product respiration, dissolves into carbonic acid in water to lower pH - .3%

N2

chemical control, filler gas (in a chip bag), doesnt dissolve in water, 78%

O2

color control, control of anaerobic pathogens (21%)

CO

antioxidant and decay inhibitor - prevents browning of meat, consumers are reluctant

carboxymyoglobin

very stable color

factors to consider in selection of film

barrier properties, machine capability, sealing relia

red meats gas comp

higher O2, lower CO2

fatty fish and bacon

no O2, Co2 and N2

fresh produce

very little CO2 and O2, mainly N2

pasta

100% N2

changes in meat fish and poultry in MAP storage

enzymatic aging, microbial spoilage (CO2 bacteriostatic activity), fat oxidation, myoglobin oxidation

fat oxidation (MAP)

reduced O2 reduce but it can still occur

myoglobin oxidation

increased CO2 promotes metmyoglobin formation -- darkening

changes in fresh produce MAP

anaerobiosis created by respiration --> anaerobic respiration and fermantation forming ethanol, acetaldehyde, and organic acids (may smell sulfur -- pseudomonas)

MAP effect on m/o

relative sensitivity to MA storage at refridgeration temperatures, inhibitory effects of carbon dioxide

most sensitive to MAP storage

pseudomonas

most resistant to MAP

clostridium

CO2 inhibitory effects

disrupting membrane function, reduction of intracellular pH, extended lag, longer generation time, reduction of bacterial population

MAP inhibition

S. aureus, salmonella, yersinia

MAP possible growth

Listeria, clostridia, big seafood concern

MAP factors of concern

initial and final gas comp, gas to product ratio, gas purity, relative permeability of film, pack design

safety issues of MAP

reduced oxygen favors anaerobic growth, extended shelf life but gives time for growth, organoleptic warning retarded, temperature abuse, concern with listeria and clostridium

days until detection of C bot - air

over 10

days until detection of C bot - CO2

19

days until detection of C bot - 90% Co2

8

days until detection of C bot - 65% CO2, 31% N2

9

sachet generator

MAP - oxygen absorbents, most employ iron powder

ethanol gas generator

MAP - water vapor penetrates sachet with food grade ethanol - antimicrobial