Chapter 10

Question 1

aerobic condition in meat spoilage

Answer 1

slime production: pseudomonas, micrococcus, streptococcus, achromobacter, bacillus

color change: production of h2o2
red -> green-brown/grey: leuconostoc, lactobacillus

Question 2

anaerobic condition of meat spoilage

Answer 2

occurs on fatty surfaces where oxygen scavenging ability is less.

predominant flora: LAB
microbes: e.coli, clostridium, pseudomonas, achromobacter, proteus

Question 3

LAB 10^7 -10^8, spoilge occurs

Question 4

meat storage close to 0 degree c

Answer 4

slime production, sour/cheesy/acid odors (end of LAB), discoloration

little growth of enterobacteriaceae at low pH lean meat. kalo high pH and deket 5c, cepet

microbial spoilage of high pH meat occurs earlier (6-8 weeks) with sulphydryl, putrid, and faecal odors

enterobacteriaceae: serratia, enterobacter, hafnia

pother microbes: achromobacter, leuconostoc, pseudomonas, flavobacterium, lactobacillus, streptococcus

Question 5

eggs spoilage

Answer 5

• sampe cloace tercemar
• salmonella enteriditis bahaya publik
• makin tua makin sering berak, muscle di dubur toned down
• contamination of gram negative bacteria: citrobacter, escheria, serratia, campylobacter, hafnia, proteus, salmonella, enterobacter

Question 6

milk spoilage

Answer 6

normal: 10^3
cows with mastitis: 10^5 (including corynebacterium, staphylococcus spp, streptococcus spp, enterobacteriaceae)
external: more than 10^6

Question 7

growth of mo in refrigrerated milk (<5c 24-48 hour) is predominated by psychrotrophs mo

Answer 7

gram negative: pseudomonas, alcaligenes, flavobacterium, alcaligenes, acinetobacter

gram positive:
bacillus, enterococci.

bacteria reaches 10^8 CFU/mL, masuk ke stationary phase, many strain excreate heat stable extracellular proteases and lipases, primary spoilage of enzymes of milk, sensoric changes detected

Question 8

milk

Answer 8

1. acid production
   streptococcus lactase, s. faecalis, bacillus calidolactis
2. gas production
   foam at milk surface RTP e. coli, refrigerated: clostridium/bacillus
3. decomposition of protein
   hydrolysis of milk protein bitter flavor (formation of polypeptide). proteolytic: pseudomonas, flavobacteriym, achromobacter, alcaliegenes, proteus, bacillus, micrococcus, serratia, clostridium
4. slime formation by bacteria
   low temperature for a long time
   type of slime formation: surface alcaliegenes, micrococcus
   whole: aerobacter aerogenes, streptococcus, L.casei, e.coli, l. bulgaricus, l. plantarum
5. alcali formation
   bacterua causes alcali reaction production of amonia (dri urea, carbs, organic acid). p. fluorecens, p. trifolii, a. viscolactis, micrococcus ureae
6. off-flavor
   - acidity: s. lactis, leuconostoc, clostridium
   - bitter: proteolytic
   - caramel flavor: s. lactis

Question 9

seafood spoilage signs

Answer 9

slime, discoloration, softening, off odors, gas production. determined by commensal flora and storage conditions

Question 10

specific spoilage organisms of seafood (SSO2) belongs to psychotrophic group

Answer 10

produces off odours and off flavours associated with spoilage

Question 11

typical spoilage microorganisms of seafood

Answer 11

pseudomonas, shewanella, s. putrefaciens (produces TMA< H2S, volatile sulphides jd bau fishy sulphides and cabbage), moraxella, acinetobacter, flavobacterium

Question 12

bacteria predominates vegetables (aeorbic mesophilic bacteria)

Answer 12

gram negative

Question 13

specific spoilage of vegetables

Answer 13

soft rots (protopectinase) by bacteria bacillus, clostridium, erwinia, pseudomonas

grey spot: botrytis cinerea
blue spot: penicillium
pink spot: trichothecium roseum
green spot: cladosporium, trichiderma

Question 14

specific spoilage of fruits

Answer 14

• blue mould spoilage: penicillium (grapes, orange)
• grey mould spoilage:
  botrytis cinerea, mucor (grapes, strawberries)
• black mould spoilage: cladosporium (apricot, cherries, peach)

Question 15

yeast in fruits grow in low pH and anaerobic condition.

Answer 15

their growth is supported by production of co2, alcohol, turbidity, flocculation, pellicles, and clearing of the product (destruction of the natural pectin by pectin esterase)

Question 16

spoilage in cereal grains is mold growing on surface

Answer 16

most common:
- aspergillus, mucor, fusarium, penicillium, rhizopus

field:
fusarium, alternaria, cladosporium

storage:
penicillum, aspergillus, euratium, wallenia

Question 17

aspergillus flavus can attack corn in the field and at storafe

Answer 17

field infection results in aflatoxin production prior to harvest. greenish-yellow to yellowish-brown, or powdery mould growth on or between corn kernels

Question 18

spoilage in nuts and oilseeds aspergillus niger and flavus can survive in peanut seed and soil

Answer 18

a. nger sooty black massess, flavus yellow green spores

Question 19

aspergillus (tamari and niger), penicillium are important lipolytic moulds. rhyzopus may also be important at higher Aw in cereals and nuts

Question 20

ravages of pests may lead to secondary invasion in cereals and nuts

Question 21

white wheat flour is bleached by an oxidising agent such as oxide of nitrogen, chlorine, nitrosyl chloride, or benzoyl peroxide

Answer 21

reduces microbial load

Question 22

to prevent growth of microorganism, moisture content has to be <13%

Question 23

mechanism of spoilage in flour

Answer 23

slight moistening of white flour jd tumbuh molds -> if acid bacteria forming present, acid fermentation begins followed by alcoholic fermentation by yeast, acetic acid fermentation by acetobacter, kalo LAB absent, micrococci is found