Journal of Experimental Food Chemistry

2-Aminoacetophenone (AAP) is mainly responsible for the “untypical aging off-flavor” (UTA) in Vitis vinifera wines, a negative change in the wine bouquet, which is described by odor taints such as ‘furniture polish’, ‘wet wool’, ‘acacia blossom’ or ‘mothball’. AAP formation can be caused by photooxidation of tryptophan (TRP), which was previously shown under model conditions, by exposing free and lysozyme–bound tryptophan to UV light to be stored in model wine containing tartaric acid, sulphur dioxide and ethanol. The aim of the present study was to demonstrate the formation of AAP from Bacillus thuringiensis (Bt) as TRP source and, therefore, to identify Bt as a possible reason for UTA appearance in wine. Bt produces toxins and spores during its sporulation phase. The toxins are proteins, which include a number of TRP residues and which are, besides the spores, responsible for its toxicity towards insects. In viticulture, Bt based products are used to fight the European grape vine moth. Applied on grapes, Bt is exposed to sunlight, where Bt-bound TRP might be photooxidized yielding AAP precursors, which are released into the grape must and transformed to AAP during acidic wine storage. To prove this hypothesis, UV irradiated and non-irradiated Bt spray liquids were first transformed into model wines, which then were stored in the absence of light. Non-irradiated Bt spray liquids produced AAP, but prior UV light exposure prevented AAP formation. In a second step, harvested grapes were studied, non-sprayed or sprayed with Bt, treated with or without UV irradiation and processed into wines. Similarly high AAP concentrations were obtained in all wines independent of the treatment with Bt or UV light, indicating that AAP precursors were already present on the studied grapes. However, the application of Bt in this study did not further enhance AAP formation, suggesting that additional factors such as aging processes of Bt residues in the vineyard might be involved.

Response surface methodology was used to investigate the effect and interactions of processing variables such as kkuaripepper powder (1.0-5.0%), olive oil (3-13%) on physicochemical, textural and sensory properties of cooked pork sausage. It was found that L* and a* values decreased; however, water-holding capacity, and a* values increased, respectively, as the amount of kkuaripepper increased. Olive oil addition decreased water-holding capacity, moisture contents, and L* values of the sausages. The adhesiveness depended on the kkuaripepper and olive oil added, as its linear effect was positive at p<0.01. Kkuaripepper addition increased the springiness and chewiness of sausages. The preference of color, flavor, taste, and overall quality depend on the addition of kkuaripepper and olive oil. The optimum formulation for pork sausage with kkuaripepper powder was 2.99 g of kkuari pepper powder and 9.12 g of olive oil. The results of this optimization study would be useful for meat industry that tends to increase the product yield for sausages using the optimum levels of ingredients by RSM (Response surface methodology).