IA, Fisheries Pitches lir and Oceans et Oceans

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i Iiiiiirque 10018630

Project Report

Fisheries Development Branch Scotia-Fundy Region Halifax, Nova Scotia

JUL 1 3 1999 LIE.iF;At,

:BEDFORD I 11J .ANOCRArH y H

~ Canada

a 3$O I

PROGRAM DEVELOPMENT DIVISION FISHERIES DEVELOPMENT BRANCH P.O. BOX 550 HALIFAX, NOVA SCOTIA B3J 2S7

NOVA SCOTIA DEPARTMENT OF FISHERIES P.O. Box 2223

AND HALIFAX, NOVA SCOTIA B3J 3C5

This is an unedited consultant's report financed in full or in part by the Fisheries Development Branch, Scotia-Fundy Region. The views expressed in this report are those of the consultant and not necessarily those of the Branch.

This report is not to be cited without written permission from the Branch Director.

Project Officers: P.J. Re 426-9938

M. Drebot 424-4560

No. 110

POTASSIUM SORBATE/METHYLCELLOLOSE TREATMENT OF ICED GUTTED COD (Gadus morhua)

By:

A.D. Woyewoda, C. Stevens, J. Evrovski, D. Singer, D. Sherwood and E.G. Bligh

Canadian Institute of Fisheries Technology P.O. Box 1000 Halifax, N.S.

B3J 2X4

April, 1986

For DSS Contract No.: OSC 84-00596

PROJECT FUNDING

Funding for this project was from 3 sources:

Fisheries and Oceans P.O. Box 550 Halifax, Nova Scotia B3J 2S7

Nova Scotia Department of Fisheries P.O. Box 2223 Halifax, Nova Scotia B3J 3C5

Research Grant to E.G. Bligh Natural Sciences and Engineering Research Council of Canada

ACKNOWLEDGEMENTS

The authors gratefully acknowledge the skillful assistance of Claude Hotton in the raw quality evaluation component of this project.

INTRODUCTION

Data from our Institute has previously shown potassium sorbate

effective as a dip for shelflife extension of cod fillets but not iced

gutted cod. Presumably the sorbate was washed away by the melting of

ice. Incorporation of sorbate into a gel could reduce loss of the

chemical from the washing action of melting ice and extend

effectiveness.

This study includes a brief literature review, a preliminary study

exploring the suitability of gels and finally, results of a pilot run

monitoring iced shelflife of gutted cod over 16 days. Another treatment

incorporating the use of "chemical ice" made from a 3% potassium sorbate

solution as requested by Mr. M. Drebot, Nova Scotia Department of

Fisheries, is also included in the pilot run.

TABLE OF CONTENTS

Page

1.0 BRIEF LITERATURE SURVEY 1

2.0 PRELIMINARY EXPERIMENT 3

2.1 Objective 3

2.2 Method 3

2.3 Results and Discussion 4

2.4 Conclusion 4

3.0 PILOT RUN 5

3.1 Objective 5

3.2 Methods 5

3.2.1 Procurement of Fish 5

3.2.2 Treatment Schedule 5

3.2.3 Treatment Solutions and Sorbate Ice 6

3.2.4 Treatment and Storage of Fish 6

3.2.5 Sampling and Microbiology 7

3.2.6 Evaluation of Raw Quality 7

3.2.7 Chemical Analysis 7

3.2.8 Sorbate Loss from Melting Sorbate Ice 8

3.2.9 Sensory Evaluation 8

3.3 Results and Discussion 9

3.3.1 Raw Quality Evaluation 9

3.3.2 Microbiology 14

3.3.3 Trimethylamine 17

3.3.4 Moisture 20

TABLE OF CONTENTS (cont'd)

Page

3.3.5 Sensory Evaluation 22

3.3.6 Loss of Potassium Sorbate from Chemical Ice 23

3.4 Conclusion 24

4.0 REFERENCES 26

5.0 APPENDICES 30

5.1 Grading Guide for Iced Groundfish 30

5.2 Form for Raw Quality Evaluation 31

5.3 Evaluation Form for Cooked Quality 32

LIST OF TABLES

Page

1. Average Temperature (C°) of Iced Cod 11

2. Comments from Raw Quality Grading Sessions 11

3. Number of Fish in Each Category According to 3 Graders 12

4. Percent of Fish in Each Grade Category 12

5. Total Aerobes (log cfu/g) of Iced Gutted Cod 14

6. Alteromonas putrefaceans (log cfu/g) of Iced Gutted Cod 15

7. Trimethylamine (mg TMA nitrogen per 100 g) of Iced Gutted Cod 18

8. Moisture Content (%) of Iced Gutted Cod 21

9. Parametric Analysis (ANOVA) of Odour of Cooked Cod Fillets 22

10. Parametric Analysis (ANOVA) of Flavour of Cooked Cod Fillets 23

11. Nonparametric Results of Sensory Evaluation 23

LIST OF FIGURES

Page

1. Overall Raw Quality Scores of Iced Cod 13

2. Raw Odor Scores of Iced Cod 13

3. Total Aerobes of Iced Cod 16

4. Log (1+mg TMA-N) of Iced Cod 19

5. Average Flesh Moisture 20

6. K-sorbate in Drip from Chemical Ice 24

1 . 0 BRIEF LITERATURE SURVEY

- 1 -

1.0 BRIEF LITERATURE SURVEY

Sorbates are widely used in the food industry as microbial

inhibitors for a range of products, eg. cheese products, baked goods,

fruit juices, fresh fruits and vegetables, wines, soft drinks, pickles,

sauerkraut and certain meat and fish products (1). Yeasts and molds are

the most affected, particularly at lower pH where sorbate/sorbic acid

effectiveness increases (1). Unfortunately the acid form is very much

less soluble than its potassium salt; 0.16 vs 139.2 g/100 ml at 20°C.

Recent research has shown that even with reduced antimicrobial

activity potassium sorbate is still somewhat effective against pathogens

Clostridium botulinum (2,3), Vibrio parahaemolyticus (4), and

Salmonellae (5). As well, P. fragi (6), Alteromonas putrefaciens (7)

and P. fluorescens (8), proven fish spoilers, are inhibited to various

degrees by sorbate. Growth of three strains of Vibrio parahaemolyticus

was delayed in flounder homogenate acidified to pH 6.2 and treated with

0.05% (w/w) sorbic acid (9). Similar results were found for A.

putrefaciens in a homogenate of English sole (10).

Success in shelflife preservation has been achieved in cod fillets

(11,12, 13), haddock fillets (14), blue grenadier fillets (15) and

scallops (16,17). The positive action of sorbate dips on fillets has

not been duplicated with round fish (12,14) probably due to a lack of

penetration or adhesion of the additive. Only where dwell time or

contact of sorbate has been extended, eg. sorbate ice, has there been

significant shelf life extension of fresh gutted fish (18,19,20,21).

2

Intimate sorbate/fish contact could be facilitated through the use

of thickening agents in the dip. Methylcellulose and

hydroxypropylmethylcellulose are two inert thickeners or suspending

agents which, widely used in bakery products, salad dressings, ice

cream, and flavour emulsions, could in conjunction with sorbate show

potential as coating agents for gutted fish.

2 . 0 PRELIMINARY EXPERIMENT

3

2.0 PRELIMINARY EXPERIMENT

2.1 Objective

To investigate the feasibility of potassium sorbate/methylcellulose

treatment of gutted cod.

2.2 Method

Combinations of methylcellulose (Methocel® A-15C, Dow Chemical

Company, Sarnia, Ontario), potassium sorbate (Monsanto Industrial

Chemicals Co., St. Louis, Mo.) and citric acid (Sigma Chemical Co., St.

Louis, Mo.) were tested for gel stability on wet fish. The mixture

which provided the best gel was Methocel® (2% w/v)/citric acid (1%)/

potassium sorbate (3%). This gel was prepared hot and cooled before

use.

Freshly landed gutted Atlantic cod (Gadus morhua) averaging 1.2 kg

were puchased from a local fish market, transported to the laboratory

and treated by one of the following:

A. No treatment

B. Methocel® (2%) dip

C. Methocel (2%)/citric acid (1%) dip

D. Methocel® (2%)/citric acid (1%)/potassium sorbate (3%) dip

After dipping, fish were iced in a ratio of 3 parts fish to 1 part

ice in large fibreglass boxes and stored in the 1-2°C chill room.

Samples were withdrawn after 0,5,8,12,16 and 20 days for Alteromonas

putrefaciens and trimethylamine (22) measurement. Three fish were

evaluated per treatment at each withdrawal. During the experiment

problems were encountered with chill room temperature control. However

- 4

the experiment was not aborted.

2.3 Results and Discussion

Significant differences were not detected in A. putrefaciens counts

between treatments but the sorbate/methylcellulose/citric acid combina-

tion significantly slowed TMA formation. On day 16 untreated control,

methylcellulose control, methylcellulose/citric acid control, and

methylcellulose/citric acid/potassium sorbate had respective TMA values

of 68, 50,50 and 13 mg nitrogen per 100 g. Considering the limited num-

' ber of fish used for the experiment and the fact that problems were en-

countered with temperature control of the chill room, the statistical

significance of the data may be questionable. In all probability TMA

values of untreated, Methocele, and Methocele/citric acid control fish

were not different. However the 3-way combination of Methocel/citric

acid/sorbate certainly had an inhibitory effect on TMA formation. This

latter combination was also superior to the controls with respect to

physical quality.

2.4 Conclusion

Sorbate in combination with citric acid and Methocele did extend

shelf life of gutted head on cod in the preliminary trial. A pilot run

with better temperature control and greater sample numbers is necessary

to prove:

- the benefit of sorbate application as a gel vs sorbate water dip

- the benefit of citric acid addition to sorbate/gel dips

3 . 0 PILOT RUN

- 5

3.0 PILOT RUN

3.1 Objective

To monitor the quality of gutted cod

- dipped in combination of potassium sorbate, Methocel® gel

and citric acid and stored on ice.

- stored on ice containing potassium sorbate

3.2 Methods

3.2.1 Procurement of fish

Cod fish (Gadus morhua) averaging 3.4 lb caught May 21, 1985 in

Chedabucto Bay, N.S., gutted at sea, transported to Halifax by

refrigerated truck and purchased by CIFT the next day, May 22, from the

Fish Basket Ltd., Eastern Passage, N.S. were treated by CIFT immediately

upon arrival.

3.2.2 Treatment

Fish were coded and dipped for 2 minutes in solutions of Table 1.

Table 1 Treatment Schedule

Code Solution

MA tap water

MB potassium sorbate (3%)

MC Methocel® 856 (1%)/citric acid (1%)

MD Methocel® 856 (1%)/potassium sorbate (3%)

ME Methocel® 856 (1%)/potassium sorbate (3%) /citric acid (1%)

MF chemical ice (potassium sorbate, 3%)

- 6

3.2.3 Treatment Solutions and Sorbate Ice

Methocelo 856 (Dow Chemical Company) purchased from Howard

Industries, Dartmouth, N.S. was mixed in 100 litre lots according to

instructions provided by first preparing a slurry in hot water and

diluting to the required concentration by addition of cold water from a

fine nozzle with vigorous stirring. Citric acid and potassium sorbate,

both food grade (Howard Industries, Dartmouth), were added during the

cooling water addition when required. Prepared solutions were stored

overnight at 2°C to cool.

Chemical ice was prepared by pouring 3% potassium sorbate into

plastic bags on 1 inch high trays and freezing in a plate freezer. The

slabs of ice were kept in the bags at room temperature to temper to

their melting point and then pulverized before application to the cod.

3.2.4 Treatment and Storage of Fish

Cod fish were dipped in groups of 12 for 2 minutes in 100 litres of

non-viscous solutions (MA or MB) and individually in the same volume of

viscous gels (MC to ME).

The fish were immediately iced with 1 part fish to 2.7 parts ice in

90 litre stromborg boxes coded by treatment. A plexiglass sheet, the

length of the box, facilitated icing of 7 fish in each half which

allowed complete removal of contents from one side without disturbing

the other. Ice was added once fish were removed.

Boxes were stacked according to treatment in an insulated enclosure

(1" Purlboarda) in the +2°C chill room. Storage conditions approximated

7

those in a fish hold, i.e. low temperature and slow melting rate of

ice. Fish in the last treatment were iced similarly with "chemical ice"

tempered to its melting point as described in section 3.2.3 but stored

in a separate enclosure.

Addition of extra ice to each box was required only once during the

16 day study indicating that the melt rate was very low.

3.2.5 Sampling and Microbiology

Seven cod fish from each treatment (one half of one box) were

evaluated 0,5,7,9,12,14 and 16 days afer dipping. Four fish per

group were microbiologically sampled by aseptically peeling back a strip

of skin from the posterior left side and excising a 20 g sample of

flesh. Total aerobes and Alteromonas putrefaceans were enumerated

according to standard procedures (28). Cod were then transferred to the

chemistry laboratory for raw quality grading and chemical analysis.

3.2.6 Evaluation of Rev Quality

Quality of seven fish per treatment was evaluated by 3 graders

according to the Fisheries and Oceans grading scheme (23) outlined in

Appendix 1 and 2. A digital thermometer (Temp-Master, model 10C, PID

instruments, Downsview, Ontario) was used for measurement of internal

temperature. Graders were not aware of codes or treatments to prevent

bias. The first grading session was 1 day after dipping.

3.2.7 Chemical Analysis

After grading, 6 complete right fillets were excised, skinned,

paired into 3 groups, macerated in a domestic food processor and 2

subsamples of each blend weighed and frozen for trichloroacetic acid

extraction and trimethylamine determination by the picric acid method

8

(24,25). Remaining fillets were packed in 1 lb waxed cartons and frozen

at -35°C for sensory evaluation. Moisture was determined in duplicate

on each blend by drying at 103°C overnight.

3.2.8 Sorbate Loss from Melting Sorbate Ice

To determine the loss of potassium sorbate from melting chemical

ice, 1 kg of crushed ice made from 3% food grade potassium sorbate

solution was placed in a Buchner funnel at room temperature.

Consecutive 20 ml aliquots were collected until the ice melted

completely. From the absorbance at 254 nm, concentration of potassium

sorbate in the drip was calculated.

3.2.9 Sensory Evaluation

A formal taste panel (in individual booths) was conducted for fish

from sampling days 9, 12 and 14 by defrosting fillets at 5°C overnight,

comminuting briefly in a food processor (with thaw drip added),

with an ice cream scoop portioning into 100 x 20 mm glass petri plates,

covering, and baking at 425°F for 12 minutes. Ten panelists each

received one numerically coded petri plate from treatments MA, MB and MF

plus two plates of good quality reference (MA) frozen on day 0, ie. one

labelled "R" and the other coded (hidden reference). Members were

instructed to taste the reference "R" before each coded sample and then

indicate their grades for odor and flavor on 10 cm grading lines

(Appendix 3). Data was analyzed parametrically by analysis of variance

(26) and non- parametrically by rank (27).

- 9

3.3 Results and Discussion

3.3.1 Raw Quality Evaluation

Average temperatures of fish in sorbate ice (MF) were generally

lowest (Table 1). During the first evaluation session, graders

commented that fish from this treatment were more firm, almost to the

point of being frozen. Subsequently, fillets from cod stored in sorbate

ice (MF) were reported to be opaque and grainy in appearance, as if

previously frozen. Such changes are sometimes observed in fish stored

under superchill conditions. Volunteered written comments of graders

are presented in Table 2. "Best treatments" were from an evaluation

during the latter part of each grading session when samples of all fish

withdrawn that day were presented to 2 graders simultaneously for an

"overall" judgement.

In general, fish were softer than normal when received, ie they may

have been recovering from a post-spawn condition; high moisture values

(see Table 8) indicate starvation. Methocel® dipped cod were glossier

than other fish, especially initially. The treatment gel was not

however visible after 1 day on ice except in one treatment, ME, where a

small amount remained in the belly cavity.

Number and percent of fish in each grade category is shown in

Tables 3 and 4. Data of Table 4, multiplied by 1,2,3 and 5 for grade

A,B,C and R, respectively, and combined is shown in Figure 1. Treatment

MC, ie Methocel® plus citric acid appears inferior in most cases.

Sorbate-dipped fish, MB, remained of good quality until day 14 when melt

water probably removed most of the chemical. Gill appearance and odor

of sorbate-dipped fish was usually better than control fish.

- 10 -

Sorbate-ice cod remained of good quality for most of the study.

Odor of fillets scored well even on day 14 (see Figure 2) and after 16

days on ice this treatment was the only one where all fish were not

rejected. Fillets from sorbate dipped cod (MB) scored better in raw

odor than most other treatments on days 7, 9 and 12.

Generally, the presence of citric acid produced a reddening of the

area along the backbone in the belly cavity. Methocel® 856 did not

appear to affect the action of potassium sorbate until day 14; it may in

fact have physically interfered with sorbate action initially. Sorbate

dip (MB) probably penetrated the gill area more extensively than when

combined with the gel and had an immediate effect on quality.

TABLE 1. Average Temperature (6C) of Iced Cod

Days MA MB MC MD ME MF Post Water Sorbate Methocel + 1% Methocel + 3% Methocel + 3% Sorbate Mortem Dip Dip Citric Acid Sorbate Sorbate + 1% Ice

Citric Acid

1 +1.9 0.0 0.0 -0.1 0.0 -1.0 5 0.0 0.0 -0.9 -0.1 0.0 -0.7 7 0.0 -0.3 +0.1 +0.4 +0.1 -1.0 9 +1.0 0.0 -0.7 0.0 +0.7 -0.1 12 +0.7 +1.1 0.0 0.0 -0.1 0.0 14 0.0 +0.4 +0.3 0.0 0.0 -0.6 16 +0.9 -0.7 0.0 0.0 0.0 -0.9

TABLE 2. Comments from Raw Quality Grading Sessions

Days Post Mortem

MA Water Dip

MB Sorbate Dip

MC Methocel + 1% Citric Acid

MD Methocel + 3% Sorbate

ME Methocel + 3% Sorbate + 1% Citric Acid

MF Sorbate Ice

1 skin slightly bleached

fillets slight- ly jellied

some white gel in belly cavity

stiff, almost frozen

5 mucous in belly cavity

7 best gills pink discolora- tion in belly cavity, discol- ored along backbone

second best gills, opaque flesh, previously frozen

9 poorest appear- ance

best skin appearance

skin slightly bleached, pink inside belly cavity

slight pink in belly cavity

pink stained belly cavity, second best skin appearance

flesh ap-pears spongy

12 red stains in belly cavity

looks best, all gills neutral in odour

very pink cavity bleached skin

pink cavity, looks good, some gills sour

pink cavity, slightly bleached, looks good

spongy flesh, like frozen, grassy odor to fillets

14 very bad best treat- ment

very bad looks good

- 12 -

TABLE 3. Number of Fish in Each Grade Category from 3 Graders

Days Post Treatment

A B

MA Water Dip

C R A

MB Sorbate Dip

B C R A

MC Methocel + Citric Acid

B C R

I I

A

MD Methocel + Sorbate

B C R

ME Methocel + Sorbate + Citric Acid A B C R A

MF Sorbate

Ice

B C R

1 Grader. 1 1 5 1 0 0 7 0 0 0 6 1 0 0 4 3 0 0 5 2 0 0 6 1 0 Grader. 2 5 2 0 0 0 7 0 0 0 4 3 0 0 4 3 0 0 5 2 0 0 4 3 0 Grader# 3 0 6 1 0 0 7 0 0 0 6 1 0 0 2 5 0 0 6 1 0 0 7 0 0

Total 6 13 2 0 0 21 0 0 0 16 5 0 0 10 11 0 0 16 5 0 0 17 4 0 Percent 29 62 10 0 0 100 0 0 0 76 24 0 0 48 52 0 0 76 24 0 0 81 19 0

5 Grader# 1 0 4 2 1 0 4 2 1 0 4 2 1 0 3 4 0 0 3 4 0 0 5 2 0 Grader. 2 0 5 2 0 0 5 2 0 0 0 6 1 0 5 2 0 0 4 3 0 1 1 5 0 Grader. 3 0 5 2 0 0 7 0 0 0 3 3 1 0 3 4 0 0 2 5 0 0 0 5 2

Total 0 14 6 1 0 16 4 1 0 7 11 3 0 11 10 0 0 9 12 0 1 6 12 2 Percent 0 67 29 5 0 76 19 5 0 33 52 14 0 52 48 0 0 43 57 0 5 29 57 10

7 Grader. 1 0 5 2 0 0 2 4 1 0 3 4 0 0 3 4 0 0 5 1 1 0 1 5 1 Grader. 2 0 5 2 0 0 3 3 1 0 1 4 2 0 5 1 1 0 5 2 0 0 2 1 4 Grader# 3 0 5 2 0 0 4 2 1 0 3 3 1 0 2 4 1 0 4 3 0 0 3 3 1

Total 0 15 6 0 0 9 9 3 0 7 11 3 0 10 9 2 0 14 6 1 0 6 9 6 Percent 0 71 29 0 0 43 43 14 0 33 52 14 0 48 43 10 0 67 29 5 0 29 43 29

9 Grader# 1 0 2 5 0 0 0 7 0 0 0 7 0 0 2 5 0 0 2 5 0 0 2 4 1 Grader. 2 0 0 5 2 0 0 7 0 0 0 1 6 0 0 3 4 0 1 1 5 0 3 2 2 Grader# 3 0 2 4 1 0 2 5 0 0 2 3 2 0 5 2 0 0 5 2 0 0 4 3 0

Total 0 4 14 3 0 2 19 0 0 2 11 8 0 7 10 4 0 8 8 5 0 9 9 3 Percent 0 19 67 14 0 10 90 0 0 10 52 38 0 33 48 19 0 38 38 24 0 43 43 14

12 Grader. 1 0 0 4 3 0 0 6 1 0 0 6 1 0 0 5 2 0 0 5 2 0 0 7 0 Grader. 2 0 0 2 5 0 0 6 1 0 0 2 5 0 0 5 2 0 0 3 4 0 0 4 3 Grader. 3 0 1 2 4 0 0 7 0 0 0 0 7 0 1 3 3 0 0 6 1 0 2 5 0

Total 0 1 18 12 0 0 19 2 0 0 18 13 0 1 13 7 0 0 14 7 0 2 16 3 Percent 0 5 38 57 0 0 90 10 0 0 38 62 0 5 62 33 0 0 67 33 0 10 76 14

14 Grader. 1 0 0 2 5 0 0 2 5 0 0 0 7 0 0 6 1 0 0 1 6 0 0 4 3 Grader. 2 0 0 1 6 0 0 0 7 0 0 0 7 0 0 2 5 0 0 1 6 0 0 2 5 Grader. 3 0 0 1 6 0 0 0 7 0 0 0 7 0 0 5 2 0 0 3 4 0 0 7 0

Total 0 0 4 17 0 0 2 19 0 0 0 21 0 0 13 8 0 0 5 16 0 0 13 B Percent 0 0 19 81 0 0 10 90 0 0 0 100 0 0 62 38 0 0 24 76 0 0 62 38

TABLE 4. Percent of Fish in Each Grade Category

Days Post Treatment

MA Water Dip

MB Sorbate Dip

MC Methocel + Citric Acid

MD Methocel + Sorbate

ME Methocel + Sorbate + Citric Acid

MF Sorbate Ice

A B C R A B C R A B C R A B C R A B C R A B C R

1 29 62 10 0 0 100 0 0 0 76 24 0 0 48 52 0 0 76 24 0 0 81 19 0 5 0 67 29 5 0 76 19 5 0 33 52 14 0 52 48 0 0 43 57 0 5 29 57 1U 7 0 71 29 0 0 43 43 14 0 33 52 14 0 48 43 10 0 67 29 5 0 29 43 29 9 0 19 67 14 0 10 90 0 0 10 52 38 0 33 48 19 0 38 38 24 0 43 43 14 12 0 5 38 57 0 0 90 10 0 0 38 62 0 5 62 33 0 0 67 33 0 10 76 14 14 0 0 19 81 0 0 10 90 0 0 0 100 0 0 62 38 0 0 24 76 0 0 62 38

475_

425..

X 0

375_

A

X 325.

8

275_

225_1

175 a

16 10 1'2 14

A MA-(CONTROL) A ma-(3x KS) ❑ MC-(ix MC + ix CIT)

▪ MD-(1z MC + 3x KS) C. ME-Cix MC + 3x KS + lx CIT)

• MF-(3z KS ICE)

O

0

O a

C

*

1_

- 13 -

FIG 1 - OVERALL RAW QUALITY SCORES OF ICED COD

525

A MA-(CONTROL) A ma-(3./.., as) ❑ MC-(1'/. MC + lx CIT)

O MD-(1v. MC + 3x KS)

• ME-(lx MC + 3x KS + lx CIT)

• MF-(3x KS ICE)

A

,

112 114 16 DAYS ON ICE AFTER TREATMENT

FIG 2 - RAW ODOR SCORES OF ICED COD

DAYS ON ICE AFTER TREATMENT

- 14 -

3.3.2 Microbiology

Total aerobes (Table 5 and Figure 3) of sorbate-iced fish (MF) were

significantly lower than all treatments except MD (Methocel® plus

sorbate) overall. Treatments in order of highest to lowest total

aerobes for days 5 to 14 with statistical differences by 2-way analysis

of variance are:

MEa MBa MAab MCab

MDbC

mFC

where common superscripts indicate no significant difference (P<0.05).

Overall, MD was not significantly different from MA, MC or MF.

Alteromonas putrefaceans (Table 6) were unexpectedly low throughout

the study. The slow growth pattern observed was similar to that found

in soft cod reported by Woyewoda et al. (28). Cod used in this study

were softer than normal and high in moisture (Table 8). Data of Table 6

is the average of duplicate determinations on each of 4 fish.

TABLE 5. Total Aerobes (log cfu/g) of Iced Gutted Cod

Days Post Mortem

MA Water Dip

MB Sorbate Dip

MC Methocel + 1% Citric Acid

MD Methocel + 3% Sorbate

ME Methocel + 3% Sorbate + 1% Citric Acid

MF Sorbate Ice

1 3.23

5 3.00 3.10 2.61 2.92 4.82 3.23 *1.54 *0.93 *0.69 *1.00 *1.29 *0.76

7 3.57 2.66 3.27 2.99 3.32 2.35 *0.88 *0.11 *0.72 *1.07 ±0.67 *0.11

9 3.61 2.83 3.48 2.91 3.75 2.86 *0.76 *0.52 *0.54 *0.71 *0.62 ±0.99

12 3.88 4.76 4.31 4.79 5.32 3.17 *0.35 *1.53 *1.16 *0.78 *1.31 *0.54

14 5.17 5.94 4.61 3.63 4.21 4.10

*0.44 ±0.33 *0.82 ±0.31 *0.74 *0.63

16 5.13 5.43 4.93 4.12 4.29 4.25

*0.77 ±0.91 ±0.36 *1.10 *0.79 *0.70

TABLE 6. Alteromonas putrefaceans (log cfu/g) of Iced Gutted Cod

Days Post Mortem

MA Water Dip

MB Sorbate Dip

MC Methocel + 1% Citric Acid

MD Methocel + 3% Sorbate

ME Methocel + 3% Sorbate + 1% Citric Acid

MF Sorbate Ice

5 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 1.3 est <1 <1

7 1.0

1 4 est fl fl fl fl fl

1.70 est 1.48 est 1.78 est 2.15 est <1 <1 <1 <1 <1 <1 1.30 est <1

9 2.30 est <1 1.70 est <1 <1 <1 1.70 est <1 2.18 est 1.30 est <1 <1 2.57 est <1 <1 <1 <1 1.00 est

<1 <1 <1 <1 1.30 est <1

12 1.60 est <1 1.60 est 1.84 est 1.90 est <1

1.60 est <1 1.30 est <1 3.28 est 1 est

2.04 est 2.08 est <1 2.91 est <1 <1 1.60 est <1 1.30 est <1 1.30 est <1

14 1.70 est 2.49 est 1 est <1 <1 <1

2.34 est 1.70 est 1 est 1 est <1 <1

2 est 2.62 est 1.90 est <1 1 est <1

2.74 est 2.73 est 1.85 est <1 1 est <1

16 1 est 1.48 est 1.78 est 2.38 est <1 <1

3.41 est 2.40 est 1.70 est <1 1.74 est 1.30

1.95 est 1.48 est 2.60 est 2.60 est 1 est <1

1.60 est 1.85 est 1.30 est 1.30 est 1 est <1

3_

--4

\ ..--, -

-

-AS , •...

--).rt ----__-

▪

---a- ,, t4,-...f ._ -

r---'''

d MA-CCONTROL)

• MB-(3m. ES)

O NC-(lx MC + lz CIT) ■ MD-tiz NC + 3% MS)

• NE-C1% MC + 3% ES + lz CIT) • MF-(3z ES ICE)

16 1'2 114 116.

- 16 -

FIG 3 - TOTAL AEROBES OF ICED COD

X

= N

0 4

X 0

C

0

DAYS ON ICE AFTER TREATMENT

- 17 -

3.3.3 Trimethylamine

Trimethylamine (TMA) a product of putrefaceans growth was

significantly lowest in sorbate iced fish, MF (Table 7 and Figure 4).

Treatments arranged from highest to lowest TMA values for days 5 to 14

with statistical differences are:

MCa

MAb MDc MEc MBd MFe

with common superscripts indicating no significant difference. Day 16

was not included in the statistical analysis since all treatments were

considered spoiled at this time, ie. greater than the 15 mg% cutoff.

Citric acid plus Methocel® dipped fish were significantly highest in TMA

overall with water dipped fish (MA), second. Sorbate plus Methocel®

with and without citric acid were better than the control but not as

good as sorbate-dipped or sorbate-iced fish. The results contradict

somewhat previous reports (12) where a sorbate dip did little to extend

shelf life of roundfish. The difference between the two experiments is

the melting rate of the ice; here it was very slow and sorbate was not

washed away. From Figure 4 it appears that the gel treatment had little

effect on TMA formation until later stages of storage while sorbate dip

without Methocel® had an immediate effect which gradually diminished.

- 18 -

TABLE 7. Trimethylamine (mg TMA nitrogen per 100 g)1 of Gutted Iced Cod

Days Post Mortem

MA Water Dip

MB Sorbate Dip

MC Methocel + 1% Citric Acid

MD Methocel + 3% Sorbate

ME Methocel + 3% Sorbate + 1% Citric Acid

MF Sorbate Ice

0 0.365 0.352 0.332

5 1.12 0.575 1.10 0.740 1.50 1.24 1.02 0.622 1.12 0.992 0.712 0.832 1.28 0.530 1.40 1.40 0.795 1.40

7 4.01 1.17 2.70 1.72 1.64 0.795 2.66 0.858 15.3 3.20 2.28 1.10 2.38 1.59 5.95 6.40 0.965 2.47

9 4.07 8.12 7.28 4.10 3.65 3.46 8.06 4.00 17.3 7.56 9.10 3.62 12.4 4.62 10.2 8.30 6.20 4.80

12 10.4 13.7 14.0 15.2 9.61 5.36 16.4 11.6 20.6 12.7 14.7 6.77 21.1 8.99 12.2 6.11 19.2 7.20

14 28.0 16.4 39.7 11.4 20.6 6.00 30.2 16.0 42.3 13.1 14.1 7.34 40.5 11.8 29.8 11.9 14.8 9.79

16 41.0 22.6 42.0 24.1 30.6 19.2 31.6 33.6 50.5 18.9 23.9 20.7 36.1 26.7 35.0 19.0 29.4 22.6

1Each data point represents an average value of duplicate analysis on each of 2 replicates from 1 blend.

10 12 14 16 DAYS ON ICE AFTER TREATMENT

- 19 -

FIG 4 - LOG (l+ngTNA-N) OF ICED COD 1 8

MA-(CONTROL)

A NB-(3Z KS) O NC-(1Z MC + lz CIT)

• ND-(1Z MC + 3Z KS)

NE-(1Z MC + 3% XS + 1Z CIT)

• NF-(3z KS ICE)

15 Mg tna cutoff _

.,..-- ...," 4 .......— ,....

.-''''

..e, .X.-',..

•

„ra' 7., : -,---- __A--------411 . 47/ ,----

/ r'./ / /7 r / rd/ /1

1.6

1.4 ,/

2

▪

83

;82.8

82.6

82.4

82.2

82 18 12 14 16

DAYS ON ICE AFTER TREATMENT

\ F r I Er

- 20 -

a

3.3.4 Moisture

Generally moisture increased slightly during the storage period in

all samples except MF which decreased (Table 8 and Figure 5). Two way

analysis of variance of moisture data from days 5 to 16 indicated that

MF was significantly lower than all other treatments (P<0.05) further

supporting the observation that sorbate-ice stored fish suffered from

slight freezing due to the depressed melting point of the chemical ice.

FIG 5 - AUERAGE FLESH MOISTURE 84 4

84.2

84

83.8

283.6 /

\I .// ,

;183.4 t\fri

W83.2 /

• MA-(CONTROL)

A MB-(3z KS) ❑ MC-(1z MC + 1 CIT)

• MD-(3z MC + 3% KS)

C) ME-(1z MC + 3z KS + lz CIT)

• MF-(3z KS ICE)

- 21 -

TABLE 8. Moisture Content (%) of Iced Gutted Cod

Days Post Mortem

MA Water Dip

MB Sorbate Dip

MC Methocel + 1% Citric Acid

MD Methocel + 3% Sorbate

ME Methocel + 3% Sorbate + 1% Citric Acid

MF Sorbate Ice

0 83.0 83.3 82.3

5 83.2 83.3 83.3 83.4 82.9 81.3 81.0 83.0 82.5 83.4 81.3 82.3 83.3 82.9 82.6 82.9 82.5 83.1

7 83.5 83.2 82.5 84.0 82.2 82.9 82.0 82.9 83.8 82.7 83.9 82.9 81.9 83.5 83.0 83.5 83.2 82.0

9 83.8 83.6 82.7 83.1 82.5 82.3 83.4 83.8 82.9 82.4 83.8 82.9 82.8 83.3 83.1 83.6 84.0 83.4

12 83.5 83.7 83.5 83.0 83.1 82.7 82.0 83.4 82.9 83.1 82.1 82.8 84.1 83.4 81.7 83.0 82.9 82.3

14 84.4 82.6 84.5 83.5 83.7 82.4 84.0 83.5 83.7 83.5 84.6 82.6 83.7 83.1 83.7 83.7 83.5 82.6

16 84.8 83.9 83.5 83.7 84.7 82.0 84.1 84.6 84.6 84.7 83.7 82.4 83.6 83.9 83.8 83.3 83.7 82.8

Average of 2 determinations on each blend.

- 22 -

3.3.5 Sensory Evaluation

Parametrically analyzed data (analysis of variance, Tables 9 and 10)

indicate that on day 9 odour of the day 0 reference was significantly

better than all other samples. Flavour of "R" was better than MA and MB

but not MF. Non-parametrically, odour of "Rn was better than MB but no

differences were found for flavour.

On day 12, "R" was superior in odour and flavour by both

statistical comparisons. At 14 days, however, odour of all samples was

different and declined in quality as R > MF > MB > MA. Flavour of MF

was not different from "R", parametrically (Table 10), but was inferior

non-parametrically (Table 11). Sorbate dipped cod (MB) and the control

(MA) were significantly poorer in flavour than "R" or MF verifying the

loss of sorbate effect in MB samples by day 14.

TABLE 9. Parametric Analysis (ANOVA) of Cooked Cod Fillets

(Best to Poorest Quality)

Day 9 Ra MFb MAb MBb

(3.62) (5.92) (6.24) (7.31)

Day 12 Ra MBb mpb MAb

(2.65) (5.41) (5.44) (7.15)

Day 14 Ra MFb MBc MAd

(2.95) (5.42) (7.22) (9.31)

*Parametric ANOVA analysis (P<0.05)

- 23 -

TABLE 10. Flavour of Cooked Cod Fillets

(Best to Poorest Quality)

Day 9

Day 12

Day 14

Ra (4.08)

Ra (2.97)

Ra (3.34)

mFab

(5.38)

MFb (5.34)

MAb (6.00)

MBb (6.61)

MBb (6.25)

MAb (6.98)

MAb (8.82)

MFa MBb (4.47) (7.68)

*Parametric ANOVA analysis (P<0.05)

TABLE 11. Non-Parametric Results of Sensory Evaluation

Day Odour

9 "R" sig. better than MB

12 "Rn sig. better than all treatments

14

All treatments sig. different from each other, ie. from best to poorest: Ra mFb MBc mAd

Flavour

No sig. differences

"R" sig. better than all treatments

nRn sig. best. MF sig. second best, ie. from best to poorest: Ra MFb MBc MAc

3.3.6 Loss of Potassium Sorbate from Chemical Ice

One kilogram of ice made from a 3% potassium sorbate solution was

allowed to thaw in a Buchner funnel. Concentration of sorbate in

collected 20 ml portions of drip is shown in Figure 6. Initial

concentrations were between 5 and 6% sorbate; original concentration

(3%) was reached once 40% of the ice had melted. This pattern of

sorbate loss is ideal for storage of fish. Release is elevated during

the initial storage period but is never lost completely, ie. decline

after the maximum is almost linear providing some sorbate to the fish

during the entire melt process. Melting temperature of the ice at the

beginning of the test was measured at -3°C.

OF

X-S

OR

DA

TE

(z) IN

DR

IP

4_

- 24 -

FIG 6 - H-SORBATE IN DRIP FROM CHEMICAL ICE

ok

eie • ski

16 36 46 56 610 86 46 106

PERCENTAGE OF ICE MELTED 3.4 Conclusion

Potassium sorbate dip, with or without Methocel® 856, improved

shelf life of gutted cod on ice. The slow melting rate of ice imposed

during the experiment influenced the results. Sorbate alone had an

immediate effect which was gradually lost while Methocel®, not showing

immediate retardation of spoilage, maintained quality during the latter

period of storage. Data of previous experiments (12) where sorbate had

little effect on shelf life of cod on ice was collected under conditions

of more rapidly melting ice.

Citric acid had no positive effect and in fact may have accelerated

spoilage, especially in terms of discoloration. Sorbate ice was clearly

the most beneficial although part of the effect must have been due to

the depressed melting point and lower temperature affecting bacterial

- 25 -

and chemical spoilage. Freshly made 3% sorbate ice was found to melt

around -3°C. Concentration in the ice was probably too high, from a

temperature standpoint and from one of economical practicality.

The authors conclude that an optimal treatment for storing gutted

cod would likely be a sorbate dip (without a gel) and subsequent storage

in sorbic acid ice at a level of approximately 1%. Such treatment would

allow for continuous bathing of the fish with sorbate thereby maximizing

effect with least effort.

4.0 ItEFERENCES

- 26 -

4.0 REFERENCES

1. Chemical Rubber Company, 1968. In Handbook of Food Additives, 2nd

Edition, Volume 1, T.E. Furia (ed.), CRC Press, Florida.

2. Sofos, J.N., F.F. Busta and C.E. Allen, 1979. Botulism control by

nitrite and sorbate in cured meats: A review. J. Food Prot. 42:9.

3. Blocher, J.C., F.F. Busta and J.N. Sofos, 1982. Influence of

potassium sorbate and pH on ten strains of type A and B Clostridium

botulinum. J. Food Sci. 47: 2028-2032.

4. Beauchat, L.R., 1980. Comparison of anti-Vibrio activities of

potassium sorbate, sodium benzoate, and glycerol and sucrose esters

of fatty acids. Appl. Environ., Microbiol. 39: 1178.

5. Park, H.S. and E.H. March, 1972. Inactivation of Salmonella

typhimurium by sorbic acid. J. Food Technol. 35:532.

6. Moustafa, H.R. and E.B. Collins, 1968. Effects of selected food

additives on growth of Pseudomonas fragi. J. Dairy Sci. 52:335.

7. Robach, M.C., 1979. Influence of potassium sorbate on growth of

Pseudomonas putrefaciens. J. Food. Prot. 42:312.

8. Robach, M.C., 1978. Effect of potassium sorbate on growth of

Pseudomonas fluorescens. J. Food Sci. 43:1886.

9. Robach, M.C. and C.S. Hickey, 1978. Inhibition of Vibrio

parahaemolyticus by sorbic acid in crab meat and flounder

homogenates. J. Food Prot. 41:699.

- 27 -

10. Chung, Y.M. and J.S. Lee, 1981. Inhibition of microbial growth in

English sole (Parophrys retulus). J. Food Prot. 44:68.

11. Debevere, J.M. and J.P. Voets, 1972. . Influence of some

preservatives on the quality of prepacked cod fillets in relation

to the oxygen permeability of the film. J. Appl. Bacterial.

35:351-356.

12. Shaw, S.J., E.G. Bligh and A.D. Woyewoda, 1983. Effect of

potassium sorbate application on shelf life of Atlantic cod (Gadus

morhua). Can. Inst. Food Sci. Technol. J. 16:237-241.

13. Anonymous, 1983. Fish bleeding, sorbate preservation studied at

Gloucester Lab. Marine Fisheries Rev. 45(3):24.

14. Regenstein, J.M. and C.E. Regenstein, 1981. The shelf life

extension of haddock in carbon dioxide-oxygen atmospheres with and

without potassium sorbate. Western European Fish Technologists'

Assoc., 11th annual meeting, Copenhagen.

15. Statham, J.A. and H.A. Bremner, 1983. Effect of potassium sorbate

on spoilage of Blue Grenadier (Macruronus norvaezelandiae) as

assessed by microbiology and sensory profiles. J. Food Prot.

46:1084-1091.

16. Bremner, B.A. and J.A. Statham, 1983. Effect of potassium sorbate

on refrigerated storage of vacuum packed scallops. J. Food Sci.

48:1042-1047.

17. Statham, J.A., 1983. Sorbate extends shelf-life of scallops.

Australian Fisheries, July.

18. Wessels, J.P.H., E. Lamprecht, J. Rodrigues and C.K. Simmonds,

1972. Preservation of hake in treated ice. J. Food Technol.

7:203.

- 28 -

19. Fey, M.S. and J.M. Regenstein, 1982. Extending shelflife of fresh

wet red hake and salmon using CO2-02 modified atmosphere and

potassium sorbate ice at 1°C. J. Food Science 47:1048.

20. Regenstein, J.M., H.O. Hultin, M.S. Fey and S.D. Kelleher, 1980.

Utilization of red hake. Marine Fish. Rev. 42(1):32-37.

21. Fey, M.S. 1980. Extending the shelflife of fresh fish by potassium

sorbate and modified atmosphere at 0-1 °C.

22. Gill, T.A. and J.W. Thompson, 1984. Rapid, automated analysis of

amines in seafood by ion-moderated partition HPLC. J. Food Science

49:603.

23. Woyewoda, A.D. and S.J. Shaw, 1984. Operational groundfish grading

and laboratory methods guide, Technical Studies Interim

Manuscript. no. 503, Fisheries and Oceans, Halifax.

24. Dyer, W.J., 1959. Report on Trimethylamine in Fish. J. AOAC

42:292.

25. Tozawa, H., R. Enokiharo, and R. Amano. 1971. Proposed

Modification of Dyer's Method for Trimethylamine Determination in

Cod Fish. In Fish Inspection and Quality Control. R. Rreuzer

(ed.), Fishing News (Books) Ltd., London, p 187-190.

26. Larmond, E. 1977. Laboratory Methods for Sensory Evaluation of

Food, Canada Dept. Ag. Pub., 1637.

27. Siegel, S. 1956. Non-parametric Statistics. McGraw Hill, New

York, p 166.

28. APHA Intersociety/Committee on Microbiological Methods for Foods

1976. Recommended general methods for the examination of fish and

- 29 -

fish products. In Microbiological Examination of Foods (M.L.

Speck, ed.), American Public Health Assoc., Washington, D.C.

29. Woyewoda, A.D., R.E. Spencer, T.A. Gill and R.G. Ackman. 1985.

Characteristics of autumn soft-textured cod. Project Report No.

109, Fisheries and Oceans, Development Branch, Scotia-Fundy Region,

Halifax, N.S.

Grading Guide for Iced Groundfish

ROUND FISH Grade A Grade S Grade C Reject

handling practise fish properly gutted and washed

fish not properly gutted and washed

temperature temperature of 4'C (40'?) or less

temperature greater than 4'C (40'F)

texture of fish flesh is firm and resilient, and springs back immediately when released

reasonably firm, some loss of resiliency, thumb indentations slowly fill out

moderately soft thumb indentations may remain in flesh

excessively soft flesh

ROUND FISH 0 1 2 3 R

neck odour characteristic odour, fresh

neutral, total absence odour, characteristic odour no longer detect- able but off-odours haven't developed

off-odour, sour, putric bilgy, ammonia, unnatural odour

gill odour characteristic of species, fresh

neutral, total absence of odour, characteris- tic odour no longer detectable but off-odours haven't developed

faint sour odour slight to moderate sour odour

very sour, strong or putrid

general appearance

.

good overall appearance skin lustrous and shiny no fading

good overall appearance very alight bleaching of akin

some loss of metallic lustre, some bleaching

.

bloom gone from skin, color faded and bleached

eyes

.

clear, bright, convex eyes

slightly sunken, or somewhat dull ,

dull and/or cloudy

. .

very dull, sunken, and cloudy

gill appearance bright red, little mucus

red, some mucus pinkish red to brownish same mucus

brown, may be covered with mucus •

FILLETS .

Grade A • Grads 2 Grade C Reject

blood clots no blood clots g than 1/2 cm circle

no combination of blood clots exceeding 4 sq ce total area (4, 1x1 squares on 11P0 measuring template) in any one fillet

one or any combinations of blood Clots which exceed 4 square cm total area in any cms fillet

texture of fillets uniform, firm fillets with little or slight gaping

reasonably floe, resilient flesh with moderate gaping

moderately soft flesh with excessive gaping. Ragged cc torn fillets permitted

excessively soft flesh wit= unacceptable amount of gaping

chalkiness and/or jolliness no jelly. none or slightly chalky

slightly jellied or moderately chalky

moderately jellied or heavy chalky

heavy jellied. Do not reject based on chalkiness

discoloration no single discoloration, nor any combination, exceeding 2 sq cm (i.e. two, 1x1 cm squares on grid of DFO measuring template) in any one fillet

no single discoloration, nor any combination, exceeding S sq cm in any one fillet

any single discoloration, or any single discoloration or combination which exceeds 50% of the total surface of any one fillet

combination the total surface area of which does not exceed SO% of the total surface area of any one fillet

fillet odour odour characteristic of species

neutral, total absence of odour

slight off-odour, but not objectionable

any objectionable odour

C.I.F.T. 1985

N

Species: Date Landed: Date Inspected,

Name of Vessels

Name of Fisherman:

Name of Landing Site:

Inspection Location:

Type of Gear:

CPV Number:

Total Catch (lbe)t Sample Size (No):

Fish (No.)

Bled

Gutted

Washed

Iced/Temp *11'

Texture . .

Grade (Table 1)

Odour at Neck . . ... ■

Odour of Gills -

General Appearance

Eves , ,

Color of Gills ...

. .

. , TOTAL POINTS

Average (Table 2) - . . .

Grade A (Average <2) —

Grade B (2.0-2.1) .

Grade C.(2.g1.2.81 . . . 1 .

Grade (Table 2)

Blood Clots

Texture

Diecolourations

Odour

Grade (Table 3)

FINAL GRADE 1111111

Grade A B C

Reject

Number of Fish

Percent (11)

ret

03 E-1

Comments'

Name Date

Evaluate each coded sample in order for odour and flavour. Please comment on unusual (uncharacteristic) aspects of any samples.

Place a slash on each grading line for each sample similar to the example below:

EXAMPLE Like Extremely

X"-

314 po 404 I I ACCEPTABILITY

97`

Dislike Extremely

PLEASE DO ALL SAMPLES FOR EACH CATEGORY

N.B. THE REFERENCE TS OF GOOD QUALITY! PLEASE TASTE TT

!!! BEFORE EACH !!! CODED SAMPLE.

ODOUR Typical Fresh

strong ammonia Putrid or

non-typical (describe)

FLAVOUR

Sea-fresh

anER12 Putrid

Objectionable or

Neutral uncharacteristic

tasteless (describe)

COMMMITS