Analysis of crab meat volatiles as possible

spoilage indicators for

blue crab(Callinectes sapidus) meat

by gas chromatography–mass spectrometry

Food Chemistry

Paul J. Sarnoski, Sean F. O’Keefe ,

Michael L. Jahncke,

ParameswarakumarMallikarjunan ,

George J. Flick

授課老師 : 邱素芬 老師學 生 : 王凱澤 B005020027

吳伊証 B995020006

Introduction

Seafood is more perishable, compared with other

muscle foods such as beef, pork, chicken, etc.

Poor handling practices

cause deterioration in fish and shellfish → the consumer(Ashie, Smith, & Simpson, 1996).

Introduction

Crab meat = free amino acids

+ high moisture content

+ loose connectivity between the collagen fibers

→ Microbial growth = Volatile → Indicator of spoilage

(Suyama & Konosu, 1987).

The objective of this study

→ Analytical method rapidly and normally

Materials and methods

Blue crab samples for GC–MS analysis

Blue Crab (Callinectes sapidus)界： 動物界 Animalia

門： 節肢動物門 Arthropoda

綱： 軟甲綱 Malacostraca

目： 十足目 Decapoda

科： 梭子蟹科 Portunidae

屬： 美青蟹屬 Callinectes

種： 藍蟹 C. sapidus

(WIKI)

Materials and methods

Blue crab samples for GC–MS analysis

Chesapeake Bay

The harvest season

→ from April to October

Materials and methods

Blue crab samples for GC–MS analysis

Cooked under pressure

at 1210C for 7–10 min.Blue Crab

Seal- Paking and

immediately frozen

Air cooled and

placed in refrigeration (2 C)

Completed within 2.5 h

Materials and methods

Blue crab samples for GC–MS analysis

Reference (0 day) samples

→ 1. -180C for 12–20 h

→ 2. -80 0C still freezer

Remaining samples

→ 1. 40C for 4,5,6 and 7 days

→ 2. -180C for 12–20 h

→ 3. -80 0C still freezer

Materials and methods

Volatile compound analysis

Solid-phase microextraction–gas chromatography–mass spectrometry

(SPME–GC–MS)

Materials and methods

Volatile compound analysis

Solid-phase microextraction–gas chromatography–mass spectrometry

(SPME–GC–MS)StableFlex™ fiber (65 um PDMS / DVB)

Injection port 270 0C for 0.5 hour.

Adsorbed Volatiles

→15 min at ambient temperature (~210C)

or →with the vial submerged

in boiling water (99.7 0C)

Fiber removed for 4 mins.

Materials and methods

15 min at temperature (~210C) Vial submerged in water (99.7 0C)

Volatile compound analysis

Solid-phase microextraction–gas chromatography–mass spectrometry

(SPME–GC–MS)

Materials and methods

Volatile compound analysis

SPME-GC-MS :For scan mode

m/z → 15-450

For SIM (Selected ion monitoring) mode

m/z → 15, 30, 42, 58, 59, 62, 63, 89, 90, and 117.

All sample groups were run in triplicate.

Especially for low concentration chemical compounds

Materials and methods

Quantitative analysis for spoilage compounds

Quantitative(Standardization)values (Sigma–Aldrich)

→ Five sample of Ammonia, TMA, and Indole.

Aqueous solutions of the standards

→ Comparison of retention and positive identification

Materials and methods

Microbial and sensory analysis

Initial bacterial load

→ AOAC approved methods( FDA Bacteriological Analytical Manual)

25 g portions + 225 mL sterile 0.1% peptone buffer

(dilution X 10)

2 min 230 RPM

35 0C for 48 h.

Aerobic plate counts (APC)

→ per gram of crab (cfu/g).

Materials and methods

Microbial and sensory analysis

Spectrum™ Descriptive Analysis Method

(Meilgaard, Civille, & Carr, 2007)

8–12 months

6 member trained sensory panelists

Classifications

High pass, mid-pass, low pass,

low fail, and high fail

Sweet, sour, bitter, salty,

ammonia, card boardy,

Materials and methods

Microbial and sensory analysis

The Result of Microbial and sensory analysis

The References and Comparing of Chemical analysis

Materials and methods

Statistical analysis

Analysis of the GC–MS data

SAS Institute

→ ANOVA

α = 0.05

Significance using a **Fisher’s LSD**

Results and Discussion

scan mode

Results and Discussion

SIM mode

Results and Discussion

Microbial and sensory analysispredict

Results and Discussion

Indicator of spoilage in some fishery products (USDC, 2009)

→ Ion-selective electrode (ISE)

but this technique measures ‘‘apparent ammonia”

→ Not only ammonia (Pivarnik, Ellis, Wang, & Reilly, 2001)

scan mode

SIM mode

Results and Discussion

Used as an indicator of spoilage in marine species

Range from 3.8 - 15.3 ppm in frozen crab meat (Yerlikaya & Gokoelu, 2004)

scan mode

SIM mode

Sample TMA peak from water HS - SPME

Crab meat contains roughly 80% moisture

Avoid water-derived

background fragments

Results and Discussion

TMA may be a more receptive indicator of

the earlier stages of spoilage.

Results and Discussion

Used as an indicator of spoilage in shrimp(Snellings et al., 2003)

scan mode

SIM mode

Sample DI - SPME

Insufficient concentrations of indole

were volatilized to be detected.Able to be detected

without heating

(99.7 0C)

Results and Discussion

Agrees well with sensory and APC group

classification.

Good chemical indicator of microbial

growth in crab meat.

Results and Discussion

Dimethylsulfoniopropionate (DMSP) → Dimethyl sulfide

微生物

Results and Discussion

Highest for day 6 samples and then decreased for the day 7 samples.

Sulfur metabolizing microorganisms may have been more active at

this point, and by day 7 became less active in the crab meat matrix.

The enzyme responsible for the breakdown reached its maximum

activity on day 6.

Results and Discussion

Ammonia

Rapidly and normally analytical method.

TMA

may be a more receptive indicator of the earlier stages

of spoilage.

Indole

Good chemical indicator of microbial growth in crab

meat.