Taste compounds in chorizo and their changes during ripening

PII:

SO309-1740(96)00098-8

Meat Science, Vol. 44, No. 4, 245--254, 1996 Copyright6 1996ElsevierScience Ltd Printed in Great Britain. All rights reserved 0309-1740/96 $15.00 +O.OO

tLSEVlER

Taste Compounds in Chorizo and their Changes during Ripening Javier Mateo,* Maria C. Dominguez, Maria M. Aguirrezkbal & Josi Maria Zumalachregui Departamento

de Higiene y Tecnologia de 10sAlimetos, Facultad de Veterinaria, Universidad de Lebn, Campus de Vegazana s/n, 24007, Le6n, Spain

(Received 14 December 1995; revised version received 1 June 1996; accepted 20 July 1996)

ABSTRACT Taste compounds in chorizea dry fermented sausage-prepared by both traditional and industrial methods, i.e. D- and L-lactic acid, acetic acid, free amino acids and ATP derivatives, were analysed. Industrial chorizo contained larger amounts of D-lactic, L-lactic and acetic acids, several amino acids (e.g. y-aminobutyric acid, phenylalanine) and hypoxanthine (Hx) than the traditional one (p ‘0.05). The variations in taste compounds during the ripening of chorizo were tracked. D-Lactic and acetic acid increased, as well as most of the amino acids. ATP derivatives showed characteristic changes, IMP decreased on the first day und inosine (Ino) changed gradually to Hx during ripening. The taste compounds contents of garlic and paprika were studied. There was an important contribution of asparagine from spices to the initial mi.xture of sausage. Copyright 0 1996 Elsevier Science Ltd

INTRODUCTION The flavour of food may be defined as the simultaneous perception of stimuli on the receptors of taste on the tongue and smell in the upper nasal cavity and of general pain, tactile and temperature receptors located throughout the mouth and throat (Flath et al., 1981). Numerous aspects have been dealt with in research regarding the flavour of food, among which is the study of the non-volatile substances that may stimulate the taste buds-taste compounds. Taste sensations are defined as sweet, salty, bitter and sour (acid). Moreover, a further basic sensation called ‘umami’ has been described as the taste of monosodium glutamate (MSG) and 5’-nucleotides such as 5’-inosinate (IMP) and 5’guanylate (GMP) (Maga, 1994). The main substances responsible for the taste of meat and meat products are inorganic salts, peptides, amino acids, organic acids, ATP breakdown products (ATP derivatives) and sugars when they are present. Dry fermented sausages are made with meat, fat, salt, spices, sugars and other added ingredients that account for the taste compounds present in the initial sausage mix. Afterwards, during the ripening, a number of phenomena occur. *To whom correspondence

should be addressed. 245

246

J. Mate0 et al.

These taste compounds undergo a set of changes and new ones are subsequently produced from proteins, lipids and carbohydrates. Thus, the ready-to-eat product acquires a particular, worthy and appreciated taste. One of the changes is the loss of water which implies an increase in the concentration of taste compounds. Carbohydrate fermentation is carried out, principally by lactic acid bacteria (LAB). D- and L-forms of lactic acid are the major substances produced, followed by acetic acid which is caused by heterofermentative LAB. The formation of these brings about a sour, tangy taste and a decrease in the pH. This taste is prevalent in quick-fermented sausages, for instance, those made in the North of Europe or North America; on the contrary, its influence on dry fermented sausages with a long ripening time such as those made in the Mediterranean countries must be rather less (Langner, 1969, 1972; Dainty & Blom, 1995). Proteolysis accounts for the formation of peptides and amino acids which usually produce sweet and bitter tastes, thus playing a substantial part in the taste of these sausages (Langner, 1969; Demeyer et al., 1974; Verplaetse et al., 1989). The role of microorganisms and/or endogenous enzymes in the proteolysis, though researched on a number of occasions (Verplaetse et al., 1989; Told& 1992, etc.), is not fully understood. Through lipolysis, fatty acids are liberated from fats, contributing to the sour taste of the sausage (Girard & Bucharles, 1988). Among the ATP derivatives, IMP is predominant in meat extract 24 h after slaughter. This compound is gradually transformed into inosine and hypoxanthine in the meat flesh (Watanabe et al., 1989). The amount of each ATP derivative is due to change, probably during the ripening of the sausage, by endogenous enzymes (Dierick et al., 1974). There have been several studies in which the levels in fermented sausages of D- and L-lactic acids (List & Klettner, 1978; Demeyer, 1992; Monte1 et al., 1993; Johansson et al., 1994, etc.), acetic acid (Langner, 1969; Halvarson, 1973; De Ketelaere et al., 1974; Dominguez & Zumalacarregui, 1991; Monte1 et al., 1993; Johansson et al., 1994, etc.) and free amino acids (Kormendy & Gantner, 1962; Reuter et al., 1968; Stanculescu et al., 1970; Langner, 1972; Cantoni et al., 1974; Dierick et al., 1974; DeMasi et al., 1990) were determined and some of these studies tracked the changes that occurred during ripening. Our work sought, on the one hand, to determine the quantities of the major part of the taste compounds, i.e. lactic acid, acetic acid, free amino acids and ATP derivatives in ready-to-eat chorizo made by both traditional and industrial methods. Moreover, we related those taste responses and thresholds found in the literature with the amounts of the taste compounds detected in the sausage. Thus, we suggested which of them were probably implicated in the taste of the product and deserve further sensorial evaluations. On the other hand, the time-related-changes in taste compounds during the ripening of chorizo were followed up. Also, the content in taste compounds of the major spices used for making chorizo-paprika and garlic-was analysed. Both events contribute towards the understanding of the mechanisms involved in the formation/degradation of taste compounds during the ripening.

MATERIAL

AND METHODS

Samples

Ten traditional and nine industrial samples of ready-to-eat Spanish chorizo were analysed. Samples of traditional chorizo were gathered from the rural area where they had been made, industrial ones were supplied by nine local manufacturers. The process of elaboration of both types of chorizo-traditional and industrial-was basically explained in the papers of Lois et al. (1987) and Dominguez and Zumalacarregui (1991). For the study of time-related changes, four batches of chorizo were elaborated according to the

Taste compounds in chorizo and their changes during ripening

247

processes used by the local butchers. Samples were taken at day O-immediately after grinding the meat and fat and just before mixing with the ingredients-and at days 1, 3, 7, 16, 32, 49 and 70 from the beginning of processing. Finally, six samples of garlic and six of Spanish paprika were supplied by local butchers. Analytical

methods

The pH was measured with a Crison micro-pH 2001 instrument by mixing 10 g of chorizo with 10 ml of distilled water. The water content was measured by drying at 102°C over 4 h as related in the international norm IS0 R-1442. D- and L-lactic and acetic acids were determined enzymatically (anonymous, 1989) from perchloric acid extracts. The procedure for preparing the perchloric extracts was as follows: 5 g of minced chorizo, 10 g of garlic or 3 g of paprika were homogenized with 20 ml of HCl04 0.6 N. Then, the slurry was centrifuged at 4000 rpm for 10 min and filtered (Whatman No. 54 paper). The precipitate was extracted again. The supernatants were combined and then neutralized with KOH 6 N and cooled at 0°C in order to precipitate the KC104 salts formed. These salts were removed by filtering with a Whatman No. 54 filter paper. Free amino acids and ATP derivatives were analysed by high-performance liquid chromatography (HPLC). The equipment used consisted of an SP 8800 Spectra-Physics ternary pump, a 20 ~1 7125 Rheodyne sample injector and a Uvikon 7305 LC Kontron absorbance detector. Separation was achieved in a reverse-phase ODS Spheri-5 stainless steel column (4.6 mm i.d. x 220 mm) equilibrated at 25°C. Integration of peak areas was performed by an SP 4290 Spectra-Physics electronic integrator. For the amino acids analysis, 10 g of sausage, 1 g of paprika or 3 g of garlic were homogenized with 85 ml 80% v/v ethanol. After standing in a water bath at 0°C for 10 min, the homogenized material was centrifuged at 4000 rpm for 10 min. The precipitate was extracted again. The supernatants were combined and then filtered (Whatman No. 54 paper). The final volume was adjusted to 200 ml with distilled water and filtered through a 0.45 /*rn membrane filter. The chromatographic procedure was that reported by Wiedmeier et al. (1982) with two modifications (Tapuhi et al., 1981): the pH of the buffer used for the pre-column derivatization and the liquid used for dissolving 5-dimethylaminonaphthalene-I-sulphonyl chloride (Dns-Cl). The formation of Dns amino acids was performed by adding 0.03 ml of the sample extract to a mix of 0.1 ml of NaHC03 buffer (0.5 M, pH 9.5) and 0.1 ml of a solution of Dns-Cl in acetonitrile (6.3 mg/ml) and then covering tightly and standing in the dark overnight. This solution was injected in the chromatograph. Separation of the peaks was accomplished by using linear gradient elution with the mobile phase in pump A consisting of 10 mM sodium acetate (NaAc) buffer (pH 4.18)‘tetrahydrofuran (95/5) and that in pump B acetonitrile/tetrahydrofuran (9OjlO). The gradient elution was: min 0, 90% A; min 30, 60% A; min 45, 60% A; min 48, 0% A, min 60, 0% A; min 68, 90% A; and the flow rate was 1 ml/min. The eluant was monitored at 254 nm. Identification and quantification were based on retention time analysis and co-injection with standards and the use of linear calibration curves of peak area vs concentration, respectively. The Dns-amino acids employed as standard were obtained from standard amino acids (Sigma) by the same method as explained with reference to the samples. For the ATP derivatives analysis, the perchloric extract was injected in the chromatograph. The procedure of Watanabe et al. (1989) was followed. The mobile phase consisted of two eluants, A and B. A was a 0.1 M KH2P04 buffer, pH 4 and B was this KH2P04 buffer containing 10% v/v methanol. The linear gradient was: min 0, 100% A; min 5, 100% A; min 30, 50% A; min 40, 0% A; min 50, 0% A; min 51, 100% A. The flow rate

J. Mate0 et al.

248

was 1 ml/min. Monitoring was carried out at a wavelength of 254 or 280 nm. Identification was based on retention time analysis, co-injection with standards and comparison of the absorbance ratio 254 nm/280 nm of the standards to that of the tentatively identified substances. Quantification was accomplished by the use of linear calibration curves of peak area vs concentration. The ATP derivatives employed as standard were obtained from Boehringer Mannheim GmbH. Statistical analysis ANOVA was used in the ready-to-eat products in order to search for significant differences between the means of the contents of the compounds quantified in traditional chorizo and the industrial one. Means of the different compounds at the different times of ripening were compared using the Newmann-Keul’s statistical test.

RESULTS

AND DISCUSSION

Ready-to-eat chorizo Table 1 shows the percentage of water, pH value and concentration of the taste compounds studied found in both traditional and industrial chorizo. Apart from the amino acids detected, in the chromatograms there were IO-12 other peaks whose identification was not carried out. These peaks might correspond to a dansyl-amide (Wiedmeier et al., 1982), ammonia, urea, several peptides, other amino acids, etc. (Saller & Czupryna, 1989). Three ATP derivatives were identified and quantified, i.e. IMP, inosine (Ino) and hypoxanthine (Hx); also, other peaks-ompounds present in the perchloric extract that absorbed at 254 nm-appeared but most of them were small and none of the larger ones were identified as ATP derivatives. The pH value and the levels of lactic acid agree with those found in other dry fermented sausages (Demeyer et al., 1979; Monte1 et al., 1993; Johansson et al., 1994). Industrial chorizo revealed a higher quantity of lactic acid than traditional. This fact is explained by the effect of sugars added to the sausage mix before stuffing (Stiebing & Radel, 1990) and the higher temperature of fermentation (Landvogt & Fischer, 1990; Incze, 1992) in the former. L-Lactic acid accounted for approximately 60% of total lactic acid in both types of chorizo and D-lactic acid for 40%, the predominance observed for L-lactic acid being statistically significant (pcO.05). Monte1 et al. (1993) and Johansson et al. (1994) also observed a preponderance of L-lactic acid. The sour, tangy taste of dry fermented sausages is mainly a consequence of lactic acid and in smaller measure of acetic acid (Acton & Keller, 1974; Liicke, 1985). Bucharles et al. (1984) suggested that large amounts of lactic acid caused an unattractive taste, D-lactate being the chemical most responsible for this. Moreover, lactic acid, owing to its involvement in the drop in pH and the subsequent loss of protein solubility, exerts an influence on the tactile mouth-feel. Amounts of acetic acid found in dry fermented sausages were usually from 10 to 20 times lower than those of lactic acid (Dainty & Blom, 1995). This was also the case for chorizo. A larger quantity of this acid was present in industrial chorizo compared to traditional. The higher temperature of fermentation appeared to increase the levels of acetate (Halvarson, 1973; Stahnke, 1995). Moreover, sugars and curing agents were factors that had an influence on the activity of microorganisms (Dominguez et al., 1989) and therefore on the production of acetate. It appears that the production of acetic acid in dry sausage becomes undesirable in dry fermented sausages for flavour reasons, since high concentrations of this acid produce a prickly, astringent taste (Weber, 1994).

Taste compounds in chorizo and their changes during ripening

249

TABLE 1

Percentage of Water, pH Value and Concentration of Lactic and Acetic Acid (mg g-’ Dry Matter), Free Amino Acids (mg gg’ Dry Matter) and ATP Derivatives (pm01 gg’ Dry Matter) Found in Traditional and Industrial Chorizo Traditional chorizo (mean i SD)

Industrial chorizo (mean * SD)

19.3 f 7.9 5.40 f 0.27

23.9 Z!Z 8.9 4.91 Zk0.34

**

6.2~k2.6 9.6 f 2.4 158*4.2 1.4*0,2

10.9 f 2.8 14.6 * 50 25.6 f 7.3 1.9Zko.4

** * ** **

Free amino acids (mg g-i DM) Tau Asn Gln Ser Asp Glu Gly + Thr Ala Arg Pro GABA Val Phe Leu + Ile LYS Total

0.98 f 0.32 0~17*0~10 0.39 f 0.36 0.71 f 0.33 0.22 f 0.27 1.76*0.80 1.43f 0.56 2.1130.75 0.19+0.14 0.62 f 0.24 0.88 f 0.27 1.22 f 0.43 1.26 f 0.36 4.22 f 1.63 1.33* 1.14 17.72~t5.87

1.29 f 0.27 0.18~tO.08 0.21*0.14 1.20 i 0.54 0.58 f 0.61 2.03 f 1.76 1.81 =tO.57 2.94kO.91 tr 0.5910.14 2.131 1.09 1.91 *to.70 I .93 f 0.50 6.03 f 1.83 1.13+ 1.02 24.45 =t 7.45

*

ATP derivatives (wmol gg’ DM) IMP In0 Hx

0.007 * 0.019 0.951 i I.155 6.928 i 1.560

0.13O~tO.261 0.026 f 0.032 8.737 f 1.804

Total

7.891 i 1.508

8.809 f 1.827

Water (%) PH

S”

Lactic and acetic acids D_z”,“,;;’

D”)

L-Lactic Total lactic Acetic

*

*

** * ** * *

* *

“Significance of the difference between the two means by ANOVA: * = p < 0.05, ** = p < 0.01, *** = p < 0.001. tr < 0.1 mg gg’ dry matter.

The most abundant free amino acids detected in fermented sausages were frequently Ala, Leu, GABA, Glu and Lys, generally up to 0.75 mg gg’ of dry matter (DM) while ornithine, Arg, Asp and B-Ala were the lowest, usually less than 0.5 mg g-’ DM; these findings agreed with those found in chorizo. The scores for many amino acids in industrial chorizo were higher than those in the traditional one. These variations may be a consequence, on the one hand, of the lower pH which stimulated the hydrolysis of myofibrillar proteins (Klement et al., 1974) and, on the other, of the differences in bacterial population observed by Dominguez et al. (1989) for each type of chorizo. The formation of GABA, the corresponding product of the decarboxylation of glutamic acid, was also favoured by the conditions stated in the ripening of industrial chorizo.

250

J. Mateo et al.

The concentrations of each amino acid in the sausage, which ranged from 500 to 3000 ppm, surpassed in most cases the threshold values cited (Haefeli & Glaser, 1990). Consequently, taking into account the taste thresholds described for the L-amino acids in water and the concentrations of the more abundant amino acids detected in chorizo, it appears that Leu and Val could produce a bitter response, Ala a sweet response and Val and Lys both sweet and bitter. In spite of these tentative assumptions, the real effect exerted by the free amino acids existing in dry fermented sausages has still not been grasped. Finally, the mean Glu content found in chorizo was about 1500 ppm and the taste response for ‘umami’ taste was of 120 ppm in water (Maga, 1983). Hence, Glu probably has an influence on this taste. IMP content was practically negligible in both traditional and industrial chorizo; in all the samples less than 0.06 pmol g-i DM. There was 30 times more Ino in traditional chorizo than in the industrial one. On the contrary, the concentration of Hx was slightly higher in industrial chorizo. It appeared that there were unknown factors which might have caused a restraining effect in the transformation of Ino to Hx in some traditional samples. Hx was the dominant ATP derivative found in chorizo. The concentrations of IMP and GMP found in chorizo were below their umami taste thresholds; 140 and 35 ppm, respectively (Maga, 1983). Ino produced a bitter taste and Hx did not account for any taste response (Terasaki et al., 1965; Dinariyeva & Safranova, 1973, cited by Gorbatov & Lyaskovskaya, 1980). All these facts would imply that nucleotides and nucleosides would be scarcely relevant to the taste of chorizo. Changes during the ripening Table 2 shows the mean amounts of the compounds studied at different days of ripening obtained from the four batches of chorizo analysed. D-Lactic acid content, which was practically insignificant at the beginning, increased after the third day of ripening, the major increase taking place between days 3 and 7. This period of time corresponds to the most pronounced development of LAB generally observed in fermented sausages (Reuter et al., 1968; Lticke, 1985). L-Lactic acid levels did not show significant changes. This behaviour for both enantiomers was also observed previously in other dry fermented sausages (Monte1 et al., 1993; Johansson et al., 1994). The amount of acetic acid increased during the first 16 days of ripening, then stabilized and showed a tendency to decrease at the end of ripening. An important initial increase in acetic acid content was also reported by the two authors mentioned above. With respect to free amino acids, an increase in the total amounts was observed, beginning to be significant from day 7. The time-related changes observed in each amino acid in chorizo were the same in broad outline as those reported by other authors for several fermented sausages. These authors found that the major free amino acids present in the initial sausage mix were Gln, Tau, Ala and Glu, whose mean concentrations ranged between 0.5 and 1 mg g-l of DM. Our results were in agreement with these, except for Lys, which is most likely due to the lack of purity of the peak of Lys registered after the chromatographic separation. Amounts of GABA, Glu, Val, Leu + Ile, Phe, Gly + Thr, Pro, Ala and Ser increased from 2 to 10 times in chorizo. An increase in the concentrations of these amino acids in other sausages was also observed, and only Glu showed noticeably different behaviour depending on the sausage in which it was studied. While Dierick et al., Cantoni et al. and DeMasi et al. observed a decrease in Glu content, the others noticed the contrary. Frequently, an increase in the levels of o-aminobutyric acid, methionine, /?-Ala, Lys and Tau was also observed. However, in chorizo, the first three amino acids were not detected while the latter two remained roughly constant during the ripening. On the contrary, it appeared that a decrease in Gln, Asn and Arg took place

a sMeans in the same row without tr < 0.05 mg gg’ dry matter.

8.01 *to.56

letter were significantly

8.3 I i 0.72b

any common

1.20”

different

h

10.97*

Total

0.16f0.07b 5.32 l I .03h 2.52 f 0.59”

5.43 f 0.86” 3.29 zk 0.07” 2.24 f 0.38”

ATP derivatives (pmol g-t DM) IMP In0 Hx

0.28*0.13h 6.18*0.62h I .86 zb0.46”

8.0 I f 0.40”

7.69 zk 0.64”

7.20 zk 0.90”

LYS Total

Arg Pro GABA Val Phe Leu + Ile

Asp Glu Gly + Thr Ala

Asn Gln Ser

1.061kO.l Ih 0.46 f 0.1 7h 0.91 ItO.12” 0.28*0.10” tr” 0.30 * 0.13” 0.44+0.12” 0.85 f 0.20” tr” 0.24zkO.I liih 0.32 5 0. I Zab 0.32*0.21” 0.27 zk 0.04” 0.70 zk 0.32”h 1.8410.71”

0.2 i 0.3” Il.1 zkO.72’ 0.56*0.14”h

52.9 f 3.0h 5.69k0.10”h

3

I.21 +0.18h 0.56 * 0.30h 0.98ItO.13” 0.24&0.12” 0.07 f 0.04” 0.21 jzO.03” 0.39 * 0.06” 0.80 f 0.09” tr” 0.23 * 0.05”h 0.24 f 0.03” 0~22+0.15” 0.23 + 0.15” 0.50 f 0.24” 1~85ztO.91”

tr” 12.2* 1.1” 0.33 f0.05”

55.5 * 0.8” 5.68*0.11”

I

TABLE

7

by Newmann

8.46+0.83h

0~14*0~09h 3.71 zk 1.98” 4.60 l I .70h

9.29 f 2.20”

I~l0*0~OS~ 0.35*0.06”h 0.82zkO.14” 0.33zto.16” tr” I .08 k0.88h 0.58*0.12” 1.15*0.15h tr” 0.28 *0.05”h 0.47 i 0.20b 0.40~k0.18”~ 0.49 l 0.30h l.15+0.22h 1.18zkO.68”

5.5 *3.3a IO.4 f 2.9” 0.88 *0.35h

I.94h

8.20 f0.32h

0.08 * 0.03h 0.87 f l.Ol= 7.25 f I .27’

l2.27i

1.02~k0.14~ 0.29 * 0. I 5”h 0.66 f 0.27”h 0.45 f 0.07” 0. I I f 0.76” I .57 f 0.55h 0.90 f 0.15b 1~57*0.19c tP 0.34f0.38Uh’ 0.77 *0.20c 0.70f0.12” 0.69*0.14k 2.17*0.49Ed 1.14*0.63”

7.7 f 2.3h IO.4 f I .3” l.22i0.33c

27.9 + 4.4’ 4.99iO.17’

test 0, < 0.0.5).

8.63S~0.81~

0. IO &0.06h I .23 f 0.86c 7.30+ 1.5oc

12.43 IIZ2.26h

I .08 f 0.03h 0.29 * 0. I Iah 0.68 f 0.26”h 0.47-r-0.21” 0.09 f 0.08” I .50 f 080b 0.89*0.19h I .62 f 0.03’ tr” 0.34 f 0.04& 0.79 * 0.24c O-66 * 0.24” 0.67f0.17k I .98 f 0.75’ 1~40zk0~61”

7.6 zt 3.0h IO.8 zk 2.9” 1~181tO.39~

37.7 f 2.8d 5.02 f 0.20’

16

8.82*0.51b

0~10*0~02~ 0.98 f I .30’ 7.73* 1.13’

14.48 i 2.57b

70

Derivatives

7~21zkl.llh

0. I I f 0.04a 0.65 f 064c 644f l.lO=

14.37 f 2.70’

I @If O.OSb 0.27*0.12ab 0.45 f 0.23b 0.48 f 0.26a 0.16+0.13” I .83 f 0.93b 1.02+0.18b I .90 f 0.27’ tr” 0.42 f 0.09’ 0.86 f 0.24c 0.98 f 0.23cd 0.82*0.14= 2.80~k0.91~ I .45 f 0.93a

7.8 f I .9h 9.7f 1.1” 0.83 zkO.25’

l7.8* I.38 5.1 I *0.21c

and ATP

I .07 f 0.05b 0.27 zk 0. lOah 0.46*0.19h 0.49 f 0.19” 0.161tO.14” I .83 f 0.52b I .06 f 0.20h 1.86kO.17’ tra 0.37 f 0.06k 0.99+0.17c 0.98 f 0.27’ 0.82~tO.17~ 2.80 f0.79dc 1.43* 1.10”

8.8f I.3b I I.1 +=2.2” I .22 * 0.42’

22.6zk 3.1’ 5.01 +0.19c

49

Free Amino Acids (mg gg’ Dry Matter) Days of the Ripening (Mean * SD)

Keul’s

at Different

’ Dry Matter),

2

45.6 + 2.9’ 5.34*0.34k

of Lactic and Acetic Acid (mg g Found in the Batches of Chorizo

1.39zkO.17” tr” I .02 f 0.04” 0. I8 f 0.08” tr” 0.22 * 0.04” 0.40 f 0.07” 0.76?cO.15” tP 0.21 &0.05” 0.20 l 0.07” 0.22 f 0.22” 0.18*0~07a 0.36zkO.15” 2.06 f I .04”

Free amino acids TJ;g gg’ DM)

Lactic and acetic acids (mg g-’ DM) D-Lactic L-Lactic Acetic

tra 12.6k 1.4” 0. I6 * 0.03”

58.4zt3.I” 569 * 0.24”h

PH

Water

pH Value and Concentration (wmol g ’ Dry Matter)

0

of Water,

Day:

Percentage

J. Mate0 et al.

252

during the ripening of fermented sausages. The same occurred in chorizo for Gln and Asn but only traces of Arg were observed, even at day 0. There were trace amounts of Asn in the minced meat and fat at day 0, which showed a characteristic increase from day 0 to day 1 was due to the spices added, as will be discussed below. The rest of the amino acids, i.e. Asp, ornithine, histidine and tyrosine, manifested varying behaviour in the different studies. The changes in ATP derivatives (Table 2) indicated that IMP was abruptly transformed into Ino, probably by endogenous enzymes, in less than 24 h after the addition of salt and/or spices. Thus, salt and/or spices presumably produced an accelerating effect on that conversion, since if they were not added a gentle and gradual change of IMP to Ino would be expected. Also, during the ripening a gradual conversion of Ino to Hx was observed, almost reaching Ino depletion. Though by a less sensible method, only Molnar et al. (1967) found similar changes in a dry fermented sausage, but the decrease in IMP was faster in chorizo. Contribution of spices Table 3 shows the content of taste compounds detected in garlic and Spanish paprika, which are the major spices used for making chorizo. ATP derivatives were not included because neither IMP, Ino or Hx were found in these spices. To our knowledge, there is little information about lactic acid, acetic acid and free amino acids in garlic and paprika. The presence of acetic acid has been reported in garlic (Laakso er al., 1989) and in dried rehydrated Capsicum unnuum (Van Ruth & Roozen, 1994). Atal and Sethi (1961) studied the free amino acid composition of garlic; as well as in our present work, Arg was one of the most abundant. Concentration

TABLE 3 of Lactic and Acetic Acids and Free Amino Acids Found in Garlic and in Spanish Paprika

Lactic and acetic acids (mg g-l) D-Lactic L-Lactic Total lactic Acetic Free amino acids (mg g-l) Asn Gln Ser Asp Glu Gly + Thr Ala Arg Pro Val Phe Leu + Ile Lys Total tr CO.1 mg gg’.

Garlic (mean f SD)

Paprika (mean f SD)

tr tr tr tr

tr tr tr 1.62 f 0.49

2.04 f 1.44 1.79 f 1.20 4.87 f 0.33 tr 1.08*0.45 0.10*0.24 0.58 f 0.54 9.47zt5.11 0.34 f 0.52 0.3 1f 0.34 tr

9.1012.00 1.28%0.41 0.60+0.53 0.26 f 0.42 0.66hO.35 0.63*0.17 1.86*0.52

0.62:rO.ll 20.76 f 11.47

0.39 :10.26 0.28 xt 0.32 0.12*0.28 0.70 * 0.30 1.00&0.17 16.88 % 3.85

Taste compounds in chorizo and their changes during ripening

253

Considering that 1% of garlic and 3% of paprika are normally added to the initial mix, seasoning with these spices was an appreciable source of taste compounds in the initial mix, i.e. Asn, acetic acid, total free amino acids and others. However, only the increase in Asn content from day 0 to day 1 was significant (see Table 2). The greater change in most of the taste compounds occurred during ripening.

ACKNOWLEDGEMENT This work is part of the ALI90-583 project financed by the Spanish CICYT research body.

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