Ultrasonic-induced Changes In The Conductivity Of Red Wine And Its Mechanism

In recent years,ultrasound has been widely applied in food field,especially in the field of wine ageing.However,the study on wine ageing induced by ultrasound is mostly about the effect of ultrasound on the physical and chemical properties of red wine.The physical and chemical properties of red wine are difficult to detect and control in the ultrasound process.We need to rely on easy to detect the indicators to reflect the changes in the process of ultrasound.Conductivity as a new detection index is applied in the food industry.As a simple,response sensitivity and inexpensive electrochemical method,the conductivity can be used to reflect the electrical properties of food.And studies have shown that significant changes in electrical conductivity can be detected during the wine aging modified by ultrasound,however,the mechanism of ultrasound-induced changes in electrical conductivity is currently unclear.Whether the electrical conductivity can be used to reflect physical and chemical properties of red wine in the ultrasonic process remains to be studied.Hence,this paper focuses on the change of conductivity in red wine during ultrasonic process,the relationship between the content of anion-cation and conductivity in red wine under different ultrasonic conditions,then building the model wine and monitoring electrical conductivity in different ultrasonic conditions,determining of the content of two iron ions and analyzing the correlation between the changes of conductivity and ferrous ions.These studies will provide a useful reference and theoretical basis for exploring the mechanism of ultrasonic induced red wine conductivity,providing a theoretical basis for the conductivity as a detection index in the process of ultrasonic aging red wine.The results obtained are as follows:1.Under the condition of ultrasonic equipment and method,the ultrasonic power density was definitely influenced by the ultrasonic parameters employed including ultrasonic frequency,initial temperature,volume of water in ultrasound bath,vessels and the vessel distance,but the ultrasonic power and the position of the container had no significant influence on the acoustic power density.Therefore,we should pay attention to these factors in the daily application of ultrasonic,and the actual power of the ultrasonic equipment is tested.2.The conductivity of red wine has an interesting change during ultrasonic process:all the Electrical conductivity of the five wines firstly showed a rapidly rising trend,then remained relatively stable and finally had a sharp going-down when the ultrasound was shut down.Moreover,the final electrical conductivity value of the red wine treated by ultrasound was significantly higher than that of the untreated.And we combined the ionic strength of the physical quantity and investigated the relationship between the ionic and the conductivity of red wine.3.The total ionic strength of the five cations and fourteen anions for each wine sample was summed up,which is consistent with the original electrical conductivity of the five wines.And these results may suggest that the wine electrical conductivity is mainly attributed to its ionic strength including the ion species,content and valence state.4.The partial cation content in red wine changed slightly in the ultrasonic and storage process.And the total cation content and ionic strength of red wine were not very obvious at different ultrasonic power and frequency.5.When the ultrasound conditions remain unchanged,the longer the ultrasonic treatment time,the less the increment of ferric ion in the storage process of red wine.This shows that the too long ultrasonic time is not conducive to the oxidation of ferrous ions.In addition,the increment of ferric ions decreased with the increase of ultrasonic frequency,but increased with the increase of ultrasonic power,however,when the power was 500 W,the increment of ferric ions decreased.In a word,the content of two valence iron decreased and the content of ferric ion increased in the model wine under ultrasound irradiation,namely ionic strength enhancement.These results may suggest that the wine electrical conductivity is related to its ionic strength including the ion species,content and valence state.6.Effect of ultrasound on the total anion strength in SanXian red wine:the total anion strength significantly changed in the treated red wines compared to the untreated wine.To be specific,the ionic strengths of most wines were increased after ultrasound treatment,the maximum value reached 82.34 mol/L,when the ultrasound worked at the power of 400 W,frequency of 25 kHz and 300 W,the ultrasonic power density of 53.36 W/L,respectively.