International Journul of Food Sclence und Technology (1987) 22, 73-16
Technical note: Chemical and sensory assessments in ripened anchovies
B . FILSINGER*, E. SISTI?. AND N . J . BERGAMASCHIT
Introduction Salting is a traditional process for the preservation of many foods including seafoods. Anchovics, as preserved, are a heavily salted product made by mixing small, somewhat oily fish, typically Engraulis species, with salt and allowing the product to mature over several months (Filsinger et a f . , 1982; Kemp, 1973). The final product has a characteristic combination of appearance, odour, flavour and texture although the reactions that produce these characteristic sensory properties are not well known.
Filsinger et al. (1982) have described a scale for the sensory assessment of the ripening process and related a non-sensory test, the Total Ester Index (TEI), to ripening time and sensory rating. This paper describes a sensory scale for the cvaluation of the quality of ripened anchovies and presents data on thc TEI and water activity of ripened products.
Keywords
Chemical assessment, fish tcchnology, salted anchovies, sensory quality, water activity.
Materials and methods Preparation of ripened, salted anchovies
Anchovies (Engraulis anchoita) were caught in the south-eastern Atlantic Ocean on the Argentinian Platform, approximately 37.4 to 38.8"S,during the Southern hemisphere spring when the fish arrive for spawning. Their weights ranged from 25-33 g/fish.
The salted products were prepared under commercial conditions. Immediately on receipt at the factory the anchovies were immersed in saturated brine and held in the brine for 1-2 days before processing. The fish were headed and partially gutted (nobbed) by hand, washed in brine and then packed in salt in barrels or concrete vats. A layer of salt was first put in the container then a layer of fish, and so on until the container was filled with alternate layers of salt and fish finishing with a layer of salt. A loose-fitting lid was put on top of the mass and weighted with stones or concrete blocks to compress the solids and expel air. During the ripening process, liquor is expressed from the fish and covers them. The salted fish were stored for about 9 months at 1 5 ~ 2 0 ° Cin order to allow the product to ripen. Samples of ripened anchovies were collected from seventeen factories for analysis.
Authors' addresses: 'Instituto Nacional d e Tecnologia Industrial, INTI Centro de Investigaciones de Tecnologia Pesquera, CITEP, Marcelo T. de Alvear 1168,7600-Mar del Plata and TSecretaria de Recursos Maritimos, Distrito Mar del Plata, Banquina de Pescadores, Puerto Mar del Plata. Argentina.
74
B. Filsinger, E. Sisti and N . J . Bergamaschi
Sensory analysis Anchovies for sensory analysis were washed in water to remove adhering salt,
filleted and examined by four expert assessors. A total of twenty-four fish from each production batch sampled were presented to the assessors in four batches of six fish each. The five factors: odour, flavour, colour, consistency and adherence were rated separately, according to the scale shown in Table 1 , and the sample mean was calculated from all factors over the four sets.
Table 1. Sensory scoring scheme for ripened anchovies
Sensory score
Factor Flavour (disregarding salt) Flesh-colour
Odour
Flesh consistency
Adherence of flesh to back-bone
100
~~~
~
Strong ham-
like cured meat
Uniformly pink
Pleasant volatile esters, strong characteristic anchovy odour
No elasticity, firm and resistant to finger pressure in the whole fish
It separates neatly. Fillets completely
80
60
Ham-like
Pinkish, redor pinkin the middle
Ham-like, slightly like mild cheese
Pinkish, deep red or pink in the middle
Pleasant volatile esters. Characteristic anchovy odour
Volatile esters
Firm and resistant
Slightly elastic, moist
Very little adherence, it separates neatly
Adherent, it separates (incomplete filleting)
40
20
Slightly hamlike. Very slightly rancid
Uneven pink, deep red in the middle. Dark red blots
Volatile esters, slightly rancid
Rancid, offflavours
Dark red, black red blots andlor black dots
Rancid, acid, ammoniacal or sulphurous off-odours
Elastic, moist Friable
Adherent, does Flesh gets torn in
not separate the filleting
easily
process
Chemical analysis Fish for chemical analysis were filleted, minced and analysed in duplicate. Total
Ester Index was determined by a modification of the AOAC (1960) procedure (Filsinger et al., 1982), salt content by the A O A C (1960) procedure and water content calculated from the loss in weight after drying at 105.+1"C for 24 hr.
Results and discussion
The scoring system described by Filsinger et at. (1982) was designed for evaluating the progress of ripening of anchovies from the initial stage through to the fully ripened product. On the basis of experience gained with that scale and following discussions with anchovy processors, a scale for rating the quality of matured anchovies was constructed (Table 1). On this scale, running from 0 to 100, the best quality has a score of 86 or greater, very good quality from 66 to 85, good quality from 46 to 65,
Quality variation in salted ripened anchovies
75.
regular quality from 26 to 4.5 and anchovies with a score of 25 or less correspond to spoiled or over-ripe product.
The ratings given to the samples of anchovies are shown in Table 2, along with salt and water contents as determined by chemical analysis. Most samples fell in the very good quality grade (scores between 66 and 85) with one graded as best quality and six graded as good quality.
Table 2. Values of salt and water contents, sensory scores and water activity for ripened anchovies
Water content Salt content
Water activity Sensory
Sample gH20/100gfish gNaClilO0gfish (w,)
scores
1
45.66
2
50.05
3
48.07
4
48.79
5
50.42
6
53.21
7
51.42
8
51.72
9
52.6
10
52.14
11
49.95
12
49.89
13
49.94
14
49.86
1s
53.59
16
48.80
17
49.70
19.00 19.65 17.54 19.05 18.11 18.09 17.48 18.59 19.27 16.95 18.29 18.82 21.29 20.41 20.25 19.53 19.42
0.70
62.2
0.72
70
0.74
77.4
0.72
78
0.74
70
0.76
72.5
0.7s
68
0.74
75
0.74
8.5
0.77
90
0.74
59.5
0.73
66.2
0.69
69.4
0.71
60.4
0.73
58.5
0.71
69.3
0.72
80.6
Salt content in the water phase of salted products is important in inhibiting microbial spoilage while allowing reactions that produce the desired properties to proceed (Mossell & Ingram, 19.55). A better measure of the ability of salt to preserve foods is given by the water activity (a,) of the food rather than by the salt content alone. The a, values of the anchovy samples were calculated from the expression
a, = 1.002-0.042 M,
where M is the molarity of salt calculated in the water phase (Lupin et al., 1981). This relationship is limited to the range of salt contents up to the point where the water phase is saturated, approximately 6.0 M, which gives a minimum a, of 0.75.
The water activities calculated from the equation are shown in Table 2 but values of a, below 0.75 almost certainly mean that undissolved salt was present in the anchovies as sampled, and do not indicate the true value. Furthermore, Doe et al. (1982) have shown that the a, of wet salted fish cannot fall below 0.75 unless the product is dried. There is no obvious association between a, as calculated and sensory score and, bearing in mind the doubt already expressed that the calculated a, measures true a, at these salt contents, it must be concluded that a, does not influencequality.
There is no association between TEI and sensory score (Fig. 1). Filsinger et al. (1982) showed that the index increases during ripening to an asymptote but as samples reported on here were fully matured it would be expected that the values would be at the asymptote. The mean value was 10.9 with a standard error of 0.3
76
B. Filsinger, E . Sisti und N . J . Bergamaschi
50
60
I
I
I
I
I
I
70
80
90
Sensory assessment
Figure 1. Total Ester Index versus sensory score. 'CDW = Corrected dry weight (Filsinger e t a / . , 1982)
The data presented hcre show that the quality of anchovies varies from batch to batch but this variation cannot be explained by variations in sa1t:water ratios at the completion of maturation. The Total Ester Index, although useful for indicating the progress of ripening, does not predict the quality of the ripened product.
Acknowledgments
Our grateful thanks are due to Mr Peter F. Howgate of the Torry Research Station, Aberdccn for assistance in revising the manuscript.
References
AOAC (1960). Official Methods of'Anulysis.Assoriufio?~of Official Agriculturul Chernisu. 9th ed. Washington DC.
Doe, P.E., Rahila Hashmi, Poulter, R.G. & June Olley (1982). lsohalic sorption isotherms. I . Journul or Food Trchndogy, 17, 125-134.
Filsinger, B.. Barassi, C.A., Lupin, H.M. & Trucco, R . E . (1982). An objective index for the evaluation of the ripening of salted anchovy. Journal of Food Technology, 17, 193-200.
Kemp. M.J. (lO73). The processing of anchovies in salt and their quality requirements for Spain. British Sruridard I~i.sti/u~ioTne, c. Rep. T 243, pp. 1-10. London.
Lupin, H.M., Boeri. R.L. & Moschiar, S.M.(19x1). Water activity and d t content relationship in
moist salted fish products. Jnurriul 01' Food
Technology, 16, 31-38. Mossel, D . A . A . & Ingrarn, M . (IOSS). The micro-
biology of the microbial spoiIage of foods. lournul Appl. Bacteriology, 18, 233-268.
(Received 15 February 1985, accepted 16 September 1986)
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