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Food Technology > Microbial Detection Of Contaminants > Flashcards

Microbial Detection Of Contaminants Flashcards

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1
Q

Hepatitis B; a viral contaminant?

A

False
Hepatitis A and norovirus

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2
Q

Listeria is a ….(Viral/ bacteria/fungal)

A

Bacteria

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3
Q

Parasitic contaminant
Examples

A

Toxoplasma gondii
Tape worm

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4
Q

Advanced microbiological contaminant detection tool

A

Nucleic acid based
(PCR, Thermal amplification, Gene chip, probe, biosensor)

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5
Q

UV Vis spectroscopy can be used to detect organic and biomolecules that are (small/large) from even SMALL samples

A

Small

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6
Q

Nano particles and their … property is used in …technology

A

SPR (surface plasma resonance)- light deprndant property
UV Vis spectroscopy

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7
Q

Beer Lambert law
Transmitance to absorbance used in ..tech

A

UV vis spectroscopy

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8
Q

UV vis can detect concentration of soecific constituent

A

True

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9
Q

Uv vis enhanced spectroscopy uses nanoparticles and is ..(more/less) sensitive than uv vis spectroscopy

A

More

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10
Q

SPR property is used in nano particle based labelling of constituents in

A

UV vis EXTENSION spectroscopy

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11
Q

Extension coefficient= ….+…
And is associated with ..tech

A

Absorption+ scattering
Uv vus extension spectroscopy

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12
Q

Using uv vis EXTENSION spectroscopy we can find conc of a wide variety of constituents?

A

True

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13
Q

Different size and shaped nanoparticles are used in un vis EXTENSION spectroscopy

A

True

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14
Q

Disadvantages of uv vis extension spectroscopy

A
  • masked in fod matrix if uv vis active food particle/ smaller food particle
  • Complex peaks- only slight shift - difficult to interpret
  • False +/- ( large matric components )
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15
Q

…and … chromatography tech are welll established in food contaminant testing due to their ability to

A

Gas
Liquid chromatography
Seperate complex mixtures

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16
Q

Major chromatographic techniques used in detecting contaminants

A

HPLC
UPLC
MDC
high pressure liquid chromatography
Ultra performance lc
Multi dimensional c

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17
Q

Using high pressure in chromatography helps detect even smaller molecules
HPLC
UPLc
Was introduced in the years

A

1973
2004

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18
Q

HPLC was proposed in ..as an alternative to… chromatography to detect….(Volatile/soluble ..) And which are heat ..(stable/unstable)

A

1973
Gas chromatography
Less volatile
Heat unstable- degrades at high temp

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19
Q

….is used to detect less volatile substances that would degrade at high temperatures

A

HPLC

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20
Q

… chromatography has higher peak seperation, sensitivity , speed and resolution and which could detect over 50 components , usually coupled with …. technique

A

UHPLC/ UPLC
Tantem mass spectroscopy

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21
Q

In multi dimensional chromatography different chromatographic techniques are compiled by using …multiple columns?
This will increase seperation efficiency in complex matrices

A

True

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22
Q

Limitation of chromatography in food contaminant detection

A

Cannot detect bacteria
Proteins
Larger molecules
Has limited range of analyte ( property and complementary sp and mp difficult)

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23
Q

Pesticide residues
Fungal or mycotoxin
Like smaller molecules can be detected using chromatography but cannot detect

A

Bacteria
Protein
Larger molecules

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24
Q

Disadvantages of chromatography

A

Time
Analyte range limited
Cannit detect bac/protein..
Not for field
Expertise
Coupling with other tech for quantification

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25
Q

Tantem mass spectroscopy is usually coupled with…(UPLC/HPLC/MDC

A

Uplc

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26
Q

Protein based detection tech is

A

Immuno assay
- LIFA - lateral flow IA
ELISA
Radio IA
Chemi luminous IA
Counting IA

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27
Q

Most commonly used protein based detection techniques under … technology are .and ..

A

Immuno assay
LFIA
ELISA

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28
Q

…is a bioanalytical technique that could measure presence and concentration of analyte using bio recognition agent

A

Immuno assay

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29
Q

..looks similar to pregnancy detection kit and are used in home or point of care and lab use

A

LFia

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30
Q

…has 4parts and uses capillary force ; diagnostic; screen agriculturally relevant protein, small molecules etc
Parts are…..
2° antibody is fixed in …part

A

LFIA
Sample pad ( with antibody)
Conjugation pad( reaction between sample and anti body)
Nitrocellulose mambrane( with 2° antibody)
Absorbent pad( absorb excess)

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31
Q

Among IA techniques, only in….(LFIA/ELISA) multiplexing can be done

A

LFIA

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32
Q

…can detect simultaneously a variety of bacterial pathogen

A

LFIA

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33
Q

LFIA is quantitative?

A

No
Pregnancy kit (can’t say how much component present)

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34
Q

LFIA is rapid with a period of…..to…

A

5-30minutes

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35
Q

iA is a bio analytical technique that uses bio recognition molecules. All IA tech are quantitative and qualitative?

A

False
LFIA is not quantitative
But ELISA is inherently quantitative

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36
Q

Read outs can be enhanced in….
Multiplexing is possible in…
…is quantitative also
…is not

A

ELISA
LFIA
ELISA
LFIA

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37
Q

Advantages and disadvantages of LFIA

A

Rapid (5-30min)
Lab, home, on point detection
Multiplexing
Simultaneously detect seceral bacterial pathogens
High sensitivity and specificity

Storage important- antibody degradable
Loss activity over time
Need further confirmation test as
Cannot enhance read out using enzymes
Sensitivity can’t be enhanced
False +/-
Only qualitative

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38
Q

LFIA uses enzymes as bio recognition agent

A

No
Antibody (1°, 2°)

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39
Q

Unlike LFIA sensitivity can be enhanced in ….by linking…..but cannot be multiplexed

A

ELISA
Antibody to an enzyme

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40
Q

Compare LFIA and ELISA

A

Lifa only qualitative but multiplexing possible, uses no enzyme and read out cant be enhanced, shorter active period of antibody makes further confirmation test
Elisa is inherently quantitative and qualitative, but cannot be multiplexed but read outs are enhanced

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41
Q

Antibody is linked to an enzyme which in term gets activated and convert a colourless substrate coloured

A

ELISA

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42
Q

ELISA can detect a variety of molecules but not simultaneously?

A

True

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43
Q

Direct, indirect, competitive, sandwich are types of …

A

ELISA ( Protein based IA)

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44
Q

How is direct ELISA different from indirect ELISA

A

Direct ELISA uses only one antibody immobilised
Indirect uses 1°, linked to 2° which is linked to enzyme

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45
Q

…is a 2 step process (ELISA) Which uses ….antibody and …enzyme( number)

A

2 primary and secondary antibody
1 enzyme 2° linked to this enzyme

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46
Q

…is a 2 step process (ELISA) Which uses ….antibody and …enzyme( number)

A

2 primary and secondary antibody
1 enzyme 2° linked to this enzyme

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47
Q

Among direct and indirect ELISA , direct is more sensitive as in this antibody is directly linked to the enzyme

A

False
Indirect is more sensitive as it has 2 antibody

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48
Q

In sandwich elisa number of antibody used is …

A

Capture antibody
1° antibody +/- 2°
ie two or more

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49
Q

In sandwich elisa the immobilised antibody is called …

A

Capture antibody
1° &/ 2° are added later

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50
Q

The two antibody used in sandwich elisa should have same epitomes

A

False
Should have different epitomes

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51
Q

Reference antigen, analyte preincubation are part of …

A

Competitive ELISA

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52
Q

Relation between signal and analyte (sample) concentration in competitive ELISA is

A

Inversely proportional
Reference antigen is coated in the well to this preincubated analyte - antibody complex added and washed, if analyte conc high, it will replace more reference antigen…which decreases signal strength

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53
Q

Pregnancy test: LFIA
Allergen test:

A

ELISA ( protein based)

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54
Q

Which is more rapid LFIA/ ELISA

A

LFIA (5-30 min)
ELISA (<24 hr)

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55
Q

Advantages and disadvantages of ELISA

A

Adv
Rapid
High sensitivity can be enhanced as well
Enzymes more shelf stable than antibody based as if LFIA
Inherently qualitative and quantitative

Cannot be multiplexed
Costly (to develop reference antigen)
Time consuming preparation
Not out of lab
Expertise needed

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56
Q

Raman scattering is ..elastic or inelastic

A

Inelastic change in tnergy and momentum frequency and wavelength

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57
Q

Most common form of scattering ( elastic or inelastic

A

Elastic
Inelastic only 1/10^ 6

58
Q

Inelastic scattering: CV Raman
Elastic scattering:

A

Reilang

59
Q

… scattering is used in …tech

A

Inelastic
SERS

60
Q

UPLC: 2004
HPLC: 1973
SERS:… also full form

A

1974
Surface enhanced raman scattering

61
Q

Inelastic scattering is rare and each constituent gave particular pattern of scattering because of difference in unbound electrons in them

A

True

62
Q

…is a dynamic technique and produces “fingerprint” spectrum and could even detect molecule level of component

A

SERs

63
Q

Adv & Disadvantage of SERS

A

Could detect even VIRUS, protein, small molecule
Sensitive

Complex output

64
Q

Although sers is sensitive and could even detect virus, its industrial applications is limited why?

A

Complicated spectrum

65
Q

…uses mostly biological molecules like enzyme, antigen, antibody, ligand etc to neasure both qualitatively and quantitativly by producing USER FRIENFLY output using a ….to change physical/ chemical changes to signals

A

Biosensors

66
Q

Output signal ~ analyte concentration in biosensors

A

True

67
Q

Components of biosensor

A

Analyte- bioreceptor - transducer- amplifier- electronics- interface/ monitor

68
Q

In a biosensor bioreceptor is actually

A

Molecular recognising material ( DNA, enzyme, antibody, whole cell, micro organism

69
Q

Transducer produces electric signals from chemical, physical , electrical changes happening, transducers examples

A

Thermister
Proton counter (pH)
Semiconductor
Poezoelectric device
Electrodes

70
Q

…are the key features required for signal generation in a biosensor

A

Specificity and selectivity of receptor for analyte

71
Q

Adv of biosensor

A

Scalability
Selectivity
Specificity
Detect even small concentration
Rapid
Portable- miniature size- cop low

72
Q

Electrode passivation,
Bio fouling
Are disadvantages of

A

Biosensors

73
Q

Disadvantages of biosensors

A

Biofouling
Electrode passivation
Affected by pH, temperature changes etc
Bioreceptor production makes it expensive
Low life span or activity lost during storage

74
Q

Biosensors can be classified based on…and .

A

Bioreceptor
Transducer element

75
Q

Biorecognition based bioreceptor classification are
1) catalytic
2) affinity
Examples for each?

A

Catalytic : enzyme, micro organism, TISSUE
affinity: antibody, WHOLE CELL

( affinity- cell)
Catalytic- tissue
AC
CT

76
Q

Microorganisms based biosensors are …( Catalytic/ affinity)

A

Affinity
Affinity- anti BODY-mo, CELL-

77
Q

Transducer based biosensors classification are

A

ELECTROCHEMICAL- potentiometer, conductometric, amperometric, ION SENSITIVE FIELD EFFECT
OPTICAL- absorbance based, spr based, fluorescence based, luminescent based
PIEZOELECTRIC- surface accoustic wave bases, bulk accoustic wave based
THERMAL

78
Q

IS FET: ….is a ….

A

ion Sensitive Field Effect transducer based biosensor

79
Q

Widely used biosensor in food contaminant detection is …..which is…classification of biosensor

A

ISFET
Transducer element based- electrochemical transducer

80
Q

Electrochemical sensing tech compiled with ISFET are

A

Impedemetric aptasensor- binding events - dna based
SWV- square wave voltametric electrode- redox of target
Amperometric electrode

81
Q

Food borne pathogens are generally detected through…

A

Nucleic acid based tech

82
Q

Asvantage of na based tech over traditional tech in detecting fb pathogens
Disadvantage

A

Rapid - min to hrs

Expertise needed

83
Q

Year of development
HPLC
UPLC
SERS
PCR

A

1973
2004
1974
1986

84
Q

NA based tech are

A

PCR - ( RTqPCR, mPCR, nested PCR)
Isothermal application -(LAMP, NASBA)
Gene probe
Gene chip

85
Q

Pcr tech developed by….in…yr

A

Kary mullos
1986

86
Q

Pcr can multiply only a part of dna sequence?

A

No
Part or wholly

87
Q

PCE as a food borne pathogens detection tech is advantageous as

A

It can distinguish between
Bac virus or fungi

Can multiply sample for further analysis

88
Q

Primers are sequences with.,.bps

A

15-20 bp
Ss na sequence

89
Q

Pcr technique needs thermal cycle because different steps need different temperatures
Denaturation-
Anhealing-
Extension -

A

95-96 °C
55-65 °C
72°C

90
Q

PCR tech used to detect or amplifying specific region

A

Nested pcr

91
Q

RT q PCR stands for

A

Real Time fluorescent quantitative pcr

92
Q

Reverse transcription pcr is used when

A

Ss rna needs to be converted to ds dna

93
Q

mpcr stands for….and is used to…

A

Multiplex pcr
Detect multiple species ( virus,yeast, e coli…)

94
Q

Most widely used pcr tech

A

RTqPCR
real time
No need for further electrophoresis

95
Q

Widely used pcr tech

A

Rtqpcr> mpcr

96
Q

Nested pcr is used when target area is long ….bp

A

14-50 bp

(Primer 15-20)

97
Q

Number of primers used in nested pcr

A

2
Outer and inner

98
Q

Stages of RTqPCR

A

2
Reverse transcription
Amplification

99
Q

RTPCR is quantitative because thyough.
.and ….we can understand

A

Levrl of fluorescence- quantity
Earliness of fluorescence - conc

100
Q

Adv of RTPCR

A

Real time
More sensitive

101
Q

Different types of rtpcr

A

Dye based- SYBR green
Probe based- taq man

102
Q

SYBR green - working

A

Is dye based rt pcr tech
The dye is an interchalating agent that would chalate only in ds nucleic acids
Therefore dye appears if complementary sequence is present during extension phase

103
Q

..tech uses a primer with reporter molecule and a conjure molecule. Only when polymerase enzyme acts, reporter is cleaved from conjure and then colour appears

A

Taq man - probe based pcr

104
Q

…tech uses an interchalating agent to detect once ds dna appears

A

SYBR green - dye based pcr

105
Q

A novel NA based tech

A

Isothermal application

106
Q

In…tech uses different primers in a cycle

A

m pcr

107
Q

Advantages &Disadvantages of m PCR

A

Rapid
Specific (uses target × 2 primers) (forward and reverse for each target)

Cannot distinguish dead and live -false +/-
Cannot identify, only detect

108
Q

Compare rtpcr to isothermal

A

Pcr has limited industrial application due to need for expertise and cost of instrument and complexity

Unlike isothermal
Rapid, no specialized equipment hence no expertise

109
Q

Different types of isothermal application are ….and their difference

A

LAMP- Loop Mediated isothermal AMPLIFICATION- used for dna
NASBA- nucleic acid sequence based amplification - rna

110
Q

Temperature maintained in LAMP & NASBA

A

Lamp- dna - 60-65
(Pcr- 95-96, 55-65, 72)
Nasba- rna - 41

111
Q

Which one is more sensitive LAMP or PCR

A

Lamp
Forms complex structure of dna maintaining a loop- which makes its detection easier
Both are real time

112
Q

In lamp amplified sequence must have bp less than …bp

A

300

113
Q

LAMP gives complex dna structure which makes detection more easy and rapid….(time)

A

30-60 min

114
Q

Adv amd disadvantage of lamp

A

Rapid (30-60 min)
Mote sensitive than pcr
More primers used 4-6

Sequence should be less ir equal to 300bp
False result if improper primer pairing
Cross contamination possible

115
Q

LFIA : 5-30 min
LAMP:

A

30-60 min

116
Q

LAMP : DNA
….: RNA

A

NASBA

117
Q

Sequence of steps and enzymes in NASBA

A

Reverse transcription: RNA– ds c dna
RNase H: digest rna strand ; ds dna– ss dna
T7 RNA Polymerase : ssdna– rna ( multiplication)

118
Q

Isothermal amplification techniques are rapid

A

True

119
Q

Gene robe tech is a novel newly developed tech?

A

False
45 year long before
1975

120
Q

Both primers and probes are ss, later one cannot initiate amplification?

A

True

121
Q

Gene probe tech uses gene characteristics like….n….

A

Gene selectivity ( its base complimentaritt based)
Repeatability

122
Q

Types of gene probe tech are ..n…

A

Gene chip
Micro dna

123
Q

Gene probe tech: southern: 1975
Gene chip: southern: …
Hplc
Uplc
Sers
Pcr

A

1989
1973
2004
1974
1986

124
Q

Principle behind gene chip

A

Nucleic acid hybridization

125
Q

Na hybridisationin gene chip can give only qualitative infrence

A

False
Signal strength can give both quantity and quality

126
Q

Asv and dis of gene chip or gene probe

A

Sensitive
Specific
Multiplexing- Can study 1000 of genes simultaneously
Rapid
Accurate
Quantitative and qualitative
HIGH THROUGHPUT

Though easy to operate, making process, isolating and synthesis of probe need expertise and costly
COMPLEX data anslysis
Skill

127
Q

Gene chip is also called

A

Micro array

128
Q

How many people are affected by food borne illness annually

A

1/10

129
Q

Who first used sers

A

Martin fleischman

130
Q

FET cannot effectively detect which pathogen ( bac/virus/fungi/parasite)

A

Parasite
Larger hence ionic variation cannot be sensed by isfet as it has low sensitivity and resolution

131
Q

mpcr can lead to false positives and cross contamination

A

It cant distinguish live and dead

132
Q

Isothermal amplification can amplify dna, rna and protein

A

False.not protein

133
Q

Gene probe: complimentarity based
Gene chip: NA hybridisation based

A

True

134
Q

ISFET: inefficient in detecting parasites but could detect toxin, bac, virus
SERS Inefficient in detecting virus
Why

A

ISFET: Parasites are larger conparitively, hence the ionic difference oroduced by them is not effectively identified by isfet because of its low resolution and sensitivity

SERS can detect virus only if their is active molecule or they might not come to the surface or sers substrate

135
Q

ISFET is not suitable for on site?

A

False
Smaller size and highly portable

136
Q

PCR can detect both live and dead but cannot distinguish

A

True

137
Q

ELUSA is a versatile tech which can detect even pesticide residue, mycotoxin and virus using appropriate antibody

A

True

138
Q

Best tech for detecting allergens in food

A

ELISA

139
Q

GMO in foid can be detected using..n …

A

PCR
NGS

140
Q

Biosensors can even detect heavy metals

A

True

Food Technology (10 decks)

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