Transmisión a través del módulo EUSART 79

Adrian Stancu1, Vladan Lukač2

Abstract

Products react different to internal and external factors during the production, shipping, preservation etc. This is due to their low or high level of chemical stability. In order to establish the evolution of food chemical stability in preservation process, a study was conducted on wine samples from the same vineyard and vintage, but which belong to two different quality grades. The wine samples were storaged at the same air temperature and relative air humidity and were tested in the same moments according to the specific period of validity. The chemical stability of physicochemical characteristics firstly was tested and then the stability of sensory characteristics. The results showed that the two wines have particular chemical stability for each characteristic.

Key words: food, chemical stability, quality grades, physicochemical characteristics, sensory characteristics

Introduction

Every product has physical, chemical, ascetical or sensory properties etc. which are necessary in the stage of designing it and after the product is obtained it contributes to satisfy the consumer’ needs. In the chemical properties category, besides properties as chemical composition, pH (acidity or alkalinity) etc. the chemical stability is not less important. In the case of foods, the importance of chemical stability is that influences the safety degree which is a major criterion in assessment of quality for both producers and consumers. The chemical stability represents the

1

Lecturer Ph.D., Petroleum-Gas University of Ploiesti, Faculty of Economic Sciences, Bulevardul Bucureşti No.39, 100.680, Ploieşti, Romania, tel: +40 721 370 367, e-mail:

[email protected]

2

resistance of an entity (product, substance, component etc.) against chemical changes which can come from internal or external factors.3 The internal factors are represented by chemical composition of product, especially the number and chemical stability of its components. For foods, the chemical stability is decreasing with the increasing of moisture,4 5 proteins, enzyme, vitamins etc. content. Then it is possible that the foods that contain components with low chemical stability should not be recommended in treating some diseases.6

The external factor refers to air temperature, relative air humidity, airflow, air chemical composition, solar radiation, biological factors,7 type and resistance of packages,8type of shipping, location of products in conveyance etc. There are few products with high chemical stability, i.e. the noble gases (He, Ne, Ar, Kr, Xe, Rn etc.)9and metals (Au, Ag, Pt etc.) which don’t react with other substances because its chemical reactivity depends on electronic structure.

Evolution of Wine Chemical Stability according to Quality Grades

A study was carried out on two white wines which belong to two different quality grades, i.e. Sauvignon Blanc(which is superior quality wine with Controlled Designation of Origin) and Dry Muscat (which is a quality superior wine) in order to establish the evolution of food chemical stability.

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Barbosa-Cánovas, G.V., Mortimer, A., Lineback, D., Spies, W., Buckle, K., Colonna, P., (2009), Global Issues in Food Science and Technology, Academic Press, Elsevier, New York, USA, p. 13

4

Golob, P., Farrell, G., Orchard, J.E., (2008), Crop Post-Harvest: Science and Technology, Crop Post-Harvest: Principles and Practice, Volume 1, Blackwell Science Ltd, USA, p. 79

5

Wrolstad, R.E., Decker, E.A., Schwartz, S.J. Sporns, P., (2005), Handbook of Food Analytical Chemistry, Water, Proteins, Enzymes, Lipids, and Carbohydrates, John Wiley & Sons, Hoboken, New Jersey, pp. 46

6

World Health Organization, Food and Agricultural Organization of the United Nations, (2004), Vitamin and Mineral Requirements in Human Nutrition, Second Edition, Sun Fung, China, p. 292

7

Petrescu, V., Pâslaru, C., Sârbu, R., (2002), Expertiză merceologică, Editura ASE, Bucureşti, p. 95-141

8

Nielsen, S.S., (2010),Food Analysis, Fourth Edition, Springer Science Business Media, New York, USA, p. 504

9

Spencer L. Seager, S.L., Slabaugh, M.R., (2010), Chemistry for Today: General, Organic, and Biochemistry, Brooks/Cole, Cengage Learning, Belmont, USA, p. 96

The Sauvignon Blanc and Dry Muscat wines were preserved at the same air temperature (15oC) and relative air humidity (75%), which are the regular preservation conditions for these wines mentioned in standards. The preservation period was different according to its grade, i.e. 60 days for Sauvignon Blanc wine and 40 days for Dry Muscat wine.

During the preservation period, it were selected four testing moments for analyzing the chemical stability of wines which take into account both the specific preservation period of each wine and the frequency of analyses (table 1).

Table 1. Correlation between the testing moments, frequency of analyses and specific preservation period of Sauvignon Blanc and Dry Muscat wines

Testing moment of the preservation period

Frequency of analyses (days)

Sauvignon Blanc Dry Muscat

Beginning 0* 0*

Half 30 20

Three-fourths 45 30

End 60 40

* Bottle day

Source:Data from own analysis.

The wine chemical stability can be highlighted by the evolution of physicochemical characteristics during the preservation period. The physicochemical characteristics tested are shown in figure 1. The objectivity of the research is ensured by the fact that both wines:

- are white; - are medium dry;

- were produced by crushing the grapes from Dealu Mare vineyard, 2005 vintage;

- were storaged at the same air temperature and relative air humidity; - were tested in the same period according to the specific period of validity (table 1).

Figure 1.The physicochemical characteristics tested

Source:Made by author.

The chemical stability of wines depends on the chemical stability of each physicochemical characteristic. Thus, in figures 2-7 is shown the evolution of chemical stability of alcohol content, reducing sugar, total acidity, volatile acidity, free sulphur dioxide and total sulphur dioxide for Sauvignon Blanc (white columns) and Dry Muscat (diagonal hatching columns).

Figure 2.Evolution of chemical stability of alcohol content for Sauvignon Blanc and Dry Muscat wines

7,5 8,5 9,5 10,5 11,5 12,5

Beginning Half Three-fourths End

12 12 12 12 11,3 11,3 11,3 11,3 A lc o h o l c o n te n t (% a lc o h o l b y v o lu m e ) Te sting moment

Source:Data from own analysis.

Physicochemical Characteristics Alcohol content Reducing sugar Total acidity Volatile acidity Free sulphur dioxide Total sulphur dioxide

Sauvignon Blanc

Dry Muscat

Figure 2 shows that the chemical stability of alcohol content is high for both wines because its level remained unchanged during the specific preservation period.

The difference of alcohol content levels of Sauvignon Blanc wine beside Dry Muscat wine is 6.19% and it is constant in the whole validity period. This means that alcohol content did not mange to convert in alcohol vapors which can lose in the air.

The evolution of chemical stability of reducing sugar for Sauvignon Blanc and Dry Muscat wines is presented in figure 3.

Figure 3.Evolution of chemical stability of reducing sugar for Sauvignon Blanc and Dry Muscat wines

9.74 8.48 9.74 8.48 9.74 8.30 9.74 8.30 7.5 8 8.5 9 9.5 10 R e d u c in g s u g a r (g /l )

Beginning Half Three-fourths End

Testing moment

Source:Data from own analysis.

In the case of reducing sugar, its chemical stability is different according to the wine grade. Thus, the reducing sugar for Sauvignon Blanc wine has higher chemical stability because its level remained unchanged during the specific preservation period.

Instead, its chemical stability is relatively low for Dry Muscat wine since after three-fourths and until the end of preservation period, the level of reducing sugar decreased with 2.12%.

In the fist half of preservation period, the difference between the reducing sugar level of Sauvignon Blanc wine is 14.86% bigger than Dry Muscat wine.

But, in the second half, it increased up to 17.35% due to decline of reducing sugar level of Dry Muscat, because the reducing sugar level of Sauvignon Blanc remained unchanged.

Figure 4 illustrates the evolution of chemical stability of total acidity for Sauvignon Blanc and Dry Muscat wines.

Figure 4. Evolution of chemical stability of total acidity for Sauvignon Blanc and Dry Muscat wines

5.73 7.34 5.73 7.34 5.73 7.40 5.73 7.40 3 4 5 6 7 8 T o ta l a c id ity (g /l ta r ta r ic a c id )

Beginning Half Three-fourths End

Testing moment

Source:Data from own analysis.

Figure 4 shows that even the Sauvignon Blanc wine has a low level of total acidity its chemical stability is higher than Dry Muscat wine.

The Dry Muscat wine has a 28.1% bigger level in the first half and 29.14% in the second half of validity period. This is due to the fact that the total acidity level of Dry Muscat wine increased in the second half of preservation period.

The total acidity level of Dry Muscat wine increased with 0.82% starting with the first day of three-fourths of preservation period.

The evolution of chemical stability of volatile acidity for Sauvignon Blanc and Dry Muscat wines is shown in figure 5.

Figure 5. Evolution of chemical stability of volatile acidity for Sauvignon Blanc and Dry Muscat wines

0.15 0.47 0.15 0.47 0.15 0.55 0.15 0.60 0.05 0.17 0.29 0.41 0.53 0.65 V o la ti le a c id ity (g /l ta r ta r ic a c id )

Beginning Half Three-fourths End

Testing moment

Source:Data from own analysis.

The evolution of chemical stability of volatile acidity for Sauvignon Blanc and Dry Muscat wines is almost the same with the total acidity with small differences.

The Sauvignon Blanc wine has a superior chemical stability of volatile acidity than Dry Muscat wine although its level is lower with 68.09% until the first half, with 72.72% at three-fourths and with 75% at the end of preservation period.

The low chemical stability of volatile acidity of Dry Muscat wine is explained by the fact that it increased with 17.02% and 27.66% beside the initial level after second half of preservation period. Instead, it didn’t change for Sauvignon Blanc.

In the case of Dry Muscat wine, it must be noticed that the volatile acidity beside total acidity had an additional increase of its level at the end of validity period.

Figure 6 shows the evolution of chemical stability of free SO2 for Sauvignon Blanc and Dry Muscat wines.

Figure 6. Evolution of chemical stability of free SO2for Sauvignon Blanc and Dry Muscat wines

65 17 50 8 39 8 23 8 0 10 20 30 40 50 60 70 F r e e S O 2 ( m g /l )

Beginning Half T hree-fourths End

Te sting mome nt

Source:Data from own analysis.

Studying the data from figure 2 at fist view it is not clear if the chemical stability of free SO2 for Sauvignon Blanc is bigger or lower beside Dry Muscat wine because both their levels changed.

For Sauvignon Blanc, the chemical stability of free SO2decreased in each moment of testing with 23.08% at the half, with 40% at the three-fourths and with 64.62% at the end of preservation period.

In the case of Dry Muscat wine, the chemical stability of free SO2 decreased at the half of preservation period with 52.94% and remained unchanged until the end of validity period.

The differences between the free SO2 levels of Sauvignon Blanc wine beside Dry Muscat wine are 282.35% at the beginning, 525% at the half, 387.5% at three-fourths and 187.5% at the end of preservation period. Thus, the biggest difference is on the half of validity period and after that it decreased rapidly.

The evolution of chemical stability of total SO2 for Sauvignon Blanc and Dry Muscat wines is presented in figure 7.

Figure 7.Evolution of chemical stability of total SO2for Sauvignon Blanc and Dry Muscat wines

162 212 162 212 162 212 162 212 0 50 100 150 200 250 T o ta l S O 2 (m g /l )

Beginning Half Three-fourths End

Testing moment

Source:Data from own analysis.

The evolution of chemical stability of total SO2 for Sauvignon Blanc and Dry Muscat wines is similar with the alcohol content with the difference that the level of Sauvignon Blanc is smaller than the one of Dry Muscat, with 23.58%.

Both Sauvignon Blanc and Dry Muscat wines have high chemical stability of total SO2, their level remained unchanged during the entire preservation period.

The chemical stability of any food influences its sensory characteristics which are the main characteristics assessed by consumers when they are testing or eating the products.

For Sauvignon Blanc and Dry Muscat wines, the study set up additional testing of the evolution of sensory characteristics level which is affected by the chemical stability.

In figure 8 are shown the four sensory characteristic of wine tested in the same four moments when the physicochemical characteristics were analyzed.

Figure 8.The sensory characteristics tested

Source:Made by author.

In figures 9-12 is shown the evolution of sensory characteristics for Sauvignon Blanc (white columns) and Dry Muscat (diagonal hatching columns).

Figure 9. Evolution of color level for Sauvignon Blanc and Dry Muscat wines 2 1.5 2 1.5 1.7 1.3 _1.2 1 0 0.5 1 1.5 2 2.5 P o in ts

Beginning Half T hree-fourths End

Te sting mome nt

Source:Data from own analysis.

Sensory Characteristics Color Clarity Bouquet Taste Sauvignon Blanc Dry Muscat

The figure 9 highlights that the color stability in low for both Sauvignon Blanc and Dry Muscat wines, i.e. its level decreased during the testing period.

For Sauvignon Blanc wine, the color level remained unchanged until the half of storage period and it declined with 15% in the three-fourths and with 40% in the end of preservation period.

In the case of Dry Muscat, the color level maintained constant until the half of preservation period also, but it decreased only with 13.33% in the three-fourths and with 33.33% in the end of storage period.

The differences between the color levels of Sauvignon Blanc wine beside Dry Muscat wine are 33.33% at the half, 30.77% at the three-fourths and 20% at the end of validity period.

The evolution of clarity level for Sauvignon Blanc and Dry Muscat wines is illustrated in figure 10.

Figure 10.Evolution of clarity level for Sauvignon Blanc and Dry Muscat wines 2 1.5 2 1.5 1.8 1.3 1.8 1 0 0.5 1 1.5 2 2.5 P o in ts

Beginning Half T hree-fourths End

Te sting mome nt

Source:Data from own analysis.

Also, the figure 10 shows that the clarity stability in low. For the Sauvignon Blanc wine, the clarity level remained unchanged until the half

of preservation period and it decreased with 10% in the three-fourths of preservation period and since this moment remained constant until the end of validity period. In the case of Dry Muscat, the clarity stability had the same evolution and proportion of changes as color. As regards the differences between the clarity levels of Sauvignon Blanc wine beside Dry Muscat wine are 33.33% at the first half, 38.46% at the three-fourths and 80% at the end of testing moment. Figure 11 presents the evolution of bouquet level for Sauvignon Blanc and Dry Muscat wines.

Figure 11. Evolution of bouquet level for Sauvignon Blanc and Dry Muscat wines 3.2 2.8 3.2 2.8 3 2 2.5 2 1 1.5 2 2.5 3 3.5 P o in ts

Beginning Half T hree-fourths End

Te sting mome nt

Source:Data from own analysis.

The figure 11 illustrates that the bouquet stability in low for both Sauvignon Blanc and Dry Muscat wines, i.e. its level decreased approximately in the same way the color did.

For Sauvignon Blanc wine, the bouquet level remained unchanged until the half of preservation period. After that, it declined with 6.25% at the three fourths and with 21.88% at the end of the testing moment.

Instead, for Dry Muscat, the bouquet level had the same evolution until the half of preservation period, but after that it decreased with 28.57% and remained constant until the end of validity period.

The differences between the bouquet levels of Sauvignon Blanc wine beside Dry Muscat wine are the same in the first half of preservation period (14.29%) and after that it reached 50% in the three-fourths and 25% at the end of preservation period. The evolution of taste level for Sauvignon Blanc and Dry Muscat wines is shown in figure 12.

Figure 12. Evolution of taste level for Sauvignon Blanc and Dry Muscat wines 10.5 10.5 10.5 10.3 10 9.5 10 9 8.5 9 9.5 10 10.5 11 P o in ts

Beginning Half Three-fourths End

Testing moment

Source:Data from own analysis.

Data from figure 12 reveals that taste of Sauvignon Blanc and Dry Muscat wines have a low stability, as well.

For Sauvignon Blanc wine, the taste level remained unchanged during the fist half of preservation period, but after it decreased with 4.76% in the three-fourths and maintained its level until the end of testing period. In the case of Dry Muscat, the taste level had a particular evolution. It declined since the second test moment with 1.9%, in the third moment with 9.52% and in the fourth moment at the end of preservation period with 14.29%. The differences between the taste levels of Sauvignon Blanc wine beside Dry Muscat wine are 1.94% at the first half, 5.26% at the three-fourths and 11.11% ate the end of validity period.

Conclusions

Only two of six physicochemical characteristics have high chemical stability for both Sauvignon Blanc and Dry Muscat wines, i.e. alcohol content and total sulphur dioxide because its level remained unchanged during the entire preservation period. Additional, the Sauvignon Blanc

wine has higher chemical stability for three physicochemical

characteristics (reducing sugar, total acidity and volatile acidity) beside Dry Muscat wine because their level remained the same in each testing moment. Instead, both Sauvignon Blanc and Dry Muscat wines have low chemical stability for the same physicochemical characteristic, i.e. free sulphur dioxide, since its level decreased.

The free sulphur dioxide of Dry Muscat wine declined more and suddenly (52.94%) at the half of preservation period and remained unchanged until the end of validity period. But, in the case of Sauvignon Blanc wine the free sulphur dioxide decreased gradually in each testing moment with proportions that not exceed the decrease of Dry Muscat (23.08% at the half and 40% at the three-fourths), with an exception at the end of testing moment when it reached 64.62%. Thus, the Sauvignon Blanc wine has a higher stability of free sulphur dioxide than Dry Muscat wine.

Even the Sauvignon Blanc wine is highly appreciated for its color beside Dry Muscat wine due to higher points, it has a smaller stability because it decreased with 1.67% and 6.67% more in the last two testing moments. The Sauvignon Blanc has slightly higher stability of the clarity beside color due to the fact that after the half of preservation period even its level

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