Uninoculated salt reduced batches (

Uninoculated salt reduced batches (RS and RF þ RS) had the lowest abundance of acetic acid, 3-hydroxy-2-butanone, 2,3-butanediol and butanoic acid (Table 2). In contrast, the RF batch showed the highest abundance of acetic acid, 2,3-butanediol and butanoic acid. The effect of the inoculated D. hansenii was significant as it produced the highest ethanol and acetaldehyde abundance whilst a significant reduction of 2,3-butanedione, acetic acid, 3-hydroxy-2-
butanone, 2,3-butanediol and butanoic acid was observed in all inoculated batches.
With respect to volatile compounds originated from amino acid degradation reactions, the most abundant compound was 3-methyl-1-butanol. In general, these compounds were mainly affected by fat reduction and D. hansenii inoculation (Table 2). Uninoculated fat reduced batches (RF and RF þ RS) were characterized by the highest abundance of branched alcohols (2 and 3-methyl-1 butanol), in addition to a high abundance of branched acids (2-methylpropanoic and 2- and 3-methylbutanoic acids) and sulphur compounds (3-thiophenethiol, 3-methylthiopropanol, and
benzothizole) in RF þ RS batch. However, salt reduction (RS batch) produced a decrease in the abundance of several compounds (2- methyl-3-buten-2-ol, 2-methyl-1-propanol, 3-methyl-3-buten-1-
ol, 3-methyl-1-butanol, methylpyrazine, 2,6-dimethylpyrazine and benzyl alcohol) while other compounds were increased (2- acetyl-1-pyrroline, 3-methlythiopropanal, benzaldehyde and benzene
acetaldehyde). The effect of D. hansenii was significant as observed by the highest HS abundance of methyl branched aldehydes, acids and sulphur compounds in all inoculated batches.
Ester compounds originated from microbial activity were affected by reformulation and D. hansenii inoculation. When fat and salt reductions were carried out together (RF þ RS) the highest significant abundance of many ester compounds was observed, while salt reduction (RS) only increased ethyl hexanoate and fat reduction (RF) augmented ethyl acetate, butyl acetate and ethyl octanoate abundance (Table 2). In contrast, inoculation of D. hansenii produced a significant increase of many ethyl ester compounds in all the inoculated batches being characterized by the high increase of ethyl 2-hydroxypropanoate and in lowest proportion
of ethyl 2-methyl and 3-methylbutanoate. Several compounds from unknown or contaminant origin were identified, being the most abundant carbon disulphide. While the highest abundance of this compound was observed in the RF þ RS batch, no effect due to yeast inoculation was detected.
An olfactometry analysis performed to determine which volatile compounds contributed to sausage aroma detected twenty-seven aroma active zones although five of them were not identified (Table 3). In addition to the green notes produced by lipid oxidation derived compounds, it was important the contribution of compounds derived from amino acid degradation and ester activity that contributed to toasted-savoury and fruity notes respectively. The abundance of these aroma compounds in the dry sausage batches was represented in Fig. 1. The reformulation produced a significant effect. Salt reduction (RS) produced the highest abundance of aroma
compounds derived from lipid autooxidation and b-oxidation and the lowest from carbohydrate fermentation reactions. Fat reduction (RF) increased the aroma compounds derived from carbohydrate fermentation reactions. In contrast, when both reductions (RF þ RS) were carried out together, an increase in all the aroma compounds from the different origins was observed except from carbohydrate fermentation and unknown origins. The effect of D. hansenii was
significant as produced the highest abundance of aroma compounds derived from amino acid degradation, ester activity and unknown compounds and the lowest of carbohydrate fermentation aroma compounds (Fig. 1). In addition, yeast inoculation reduced significantly the aroma compounds derived from lipid autooxidation and b-oxidation reactions in the salt reduced batch (RS þ Y) that were highly increased in the uninoculated batch (RS).