Table 1 shows the pH value, chromatic characteristic and apparent viscosity of singular ingredients used in the formulation of the “red phase” of vegetable Salami
. The obtained results have shown that vegetables such as tomato and pepper
, kept a pH value close to safety (4.5) even after the blanching treatment (Table 1A) [13
]. The colorimetric indexes showed the typical values of red-yellow vegetables. Carrots have presented the highest value of yellow index (47.86 ± 1.13) that can be attributed to high content of carotenoids that determine the typical yellow/orange/red color of fruits and vegetables [14
]. Redness and yellowness were also very high in pepper, while, as reported in literature, the blanching treatment had amplified the brightness of all vegetables. As expected, the aw
value of all samples were not significantly different. Data related to apparent viscosity however, have pointed out that pepper had poor rheological characteristics (viscosity values less than 10 Pa*s) compared to tomato, carrot and potato that had a viscosity values ranged from 107 to 192.91 Pa*s. That information was very useful to determine the percentages of vegetables to use in the formula. Those percentages were chosen after preliminary determination (data not shown). The viscosity of final formula with different percentages of vegetables spices and extra virgin olive oil
was 151 Pa*s (Table 1B).
The pH value of mixed vegetables was significantly influenced by the addition of concentrated tomatoes sauce, that determined a significant increase of a* and a slight decrease of brightness too.
The summary of those data permitted to choose that formula for the addition of white green vegetables.
Table 2 showed the pH values and the colorimetric determinations of the white-green vegetables before and after the blanching treatments (with or without the addition of acids).
The acidifying-blanching carried out on white-green vegetables with the three acids evidenced that lactic acid and citric acid had a higher effectiveness on lowering of pH in all vegetable matrixes studied. PH reduction may confer some organoleptic characteristic changes such as flavor, taste, color, and texture [15
]. Among these, the possibility of imparting a sour taste and chlorophyll degradation are the main drawbacks of acidifying treatments. The most important sensorial characteristic of acidulants is sourness but organic acids may confer other non-sour flavors as well as bitterness and astringency [17
]. It may be expected acetic and citric acids have a greater congruency respectively with vinegar and citrus flavored systems rather than lactic acid that is commonly associated with milk/yogurt systems. A more deep knowledge concerning the effects of organic acids on sour taste of model systems and vegetables food
are necessary to give the possibility to control the organoleptic impact on the final products [13
]. As reported in literature, the color of green vegetables is mainly determined by the chlorophyll pigments that changes during blanching treatments by migration into the blanching water [18
Results related to brightness index (L*) as affected by different blanching treatments showed an initial increase of L* values. Some authors attributed that behaviour to air removal around the fine hairs on the surface of the plant and to the expulsion of air between the cells of vegetable tissues [19
]. The presence of different acids in hot water, reduced drastically L* index: that is probably due to the high penetration of acidified water into the cells.
Figure 1 reports the values of shear stress (N/mm2
) in blanched and acidified vegetables. After acidifying-blanching treatment, vegetables did not excessively lose their texture. In particular, samples that preserved the maxim consistency were those blanched with lactic acid. In view of that, they were used to simulate the “fat fraction” of Salami
Figure 2 shows the values of shear stress of the different formula of vegetable Salami
. The formulation containing xanthan gum and wheat flour has shown shear stress values very similar to meat Salami
. Those data are confirmed by hardness values that show how the formula containing xanthan gum and wheat flour shows mechanical properties similar to meat Salami
(Figure 3 and 4) except for springiness that did not show any significant difference (data not shown).
That formula was chosen to inoculate the selected microbial starter that allowed conducing the fermentation in vegetable matrix up to a pH of safety. The obtained vegetable Salami
were ripened for eighteen days at 25°C. Again, the pH, aw, L*, a*, b*, shear stress and mechanical properties of vegetable Salami
were monitored during ripening stages.
Figure 5 shows the pH variation as a function of ripening time. After four days of ripening, the pH reaches a value below 4.5 that could be considered safe.
The chromatic characteristics of vegetable Salami
during ripening have shown a reduction of L* (from 50.27 to 39.02) and b* indexes (from 44.92 to 30.59), while the a* index did not show any significant change. That behaviour could be mainly attributed to the gradual dehydration
of vegetable matrix rather than oxidation of pigments
present in red fraction.
Concerning the aw
, a gradual reduction was observed up to 15 days of ripening
, after that the aw values remain constant at about 0.9 (Figure 6).
Regarding the mechanical properties of vegetable Salami
, a sudden increase of shear stress force was recorded as a function of maturation up to eighteenth day of ripening (Figure 7). In addition, the hardness, the chewiness and springiness of the slices subjected to compression analysis showed the same trend (Figures 8-10). Those data permitted to assert that it would be appropriate to extend the ripening of this kind of products up to eighteen days.
The concentration of lactic acid bacteria at the end of ripening time was 108
CFU/g vs 1013
CFU/g initial inoculum. This value represents the minimum threshold to consider a food as probiotic in vitro.
Figure 11 shows the judgments emerged from the comparison of vegetable Salami
with a common pickle. Samples of vegetable Salami
showed the highest score for all the considered characteristics. Finally, Figure 12 showed a sample of vegetable Salami
at the end of ripening stage.