**7. Pulsed light**

Pulsed light (PL) is the use of wide spectrum (170–2600 nm) high intensity light [57] applied in short flashes during a few microseconds. The spectrum includes ultraviolet, visible, and near infrared radiation. PL spectrum is quite similar to the solar radiation, but having lower wavelengths from the UV (<320 nm), which, in the case of sun light, these are filtered by the ozone layer in the atmosphere. The intensity of light can reach values 105 folds higher than the sun radiation at sea level [58]. PL technology uses very short energization times, for example, a flash lamp applying energy of 300 J during 300 μs produces a peak intensity of 1 MW which produces ca. 1 kW/cm<sup>2</sup> on the irradiation surface. PL was initially used in Japan in the 1970s; later, in 1988, it was developed by a Californian company PurePulse Technologies Inc., but the applications in the food industry increased after it was approved by FDA for food processing [59].

The antimicrobial effect of PL is due to dimerization of DNA pyrimidines promoted by the 254 nm UV radiation but also due to the localized instantaneous heating producing membrane and cell wall breakage [57]. The effect on membrane

**Figure 16.**

*Pulsed light system to treat grape surface for the elimination of microorganisms in a continuous flow.*

**41**

*Emerging Technologies to Increase Extraction, Control Microorganisms, and Reduce SO2*

external appearance and sensory quality of food [60] (**Figure 16**).

and cell walls can be observed by electronic microscopy, and it is associated to a higher concentration of eluted protein [60]. These effects affect vegetative and spore forms of microorganisms. *Saccharomyces* and non-*Saccharomyces* yeasts and lactic acid bacteria are controlled in grapes at low temperature and without effect in

Currently, PL devices not only for continuous food treatment, but also for the sterilization of food packaging are available [61]. The PL equipment is formed by an electronic module containing both control and monitoring systems, high voltage components for the flashing lamps, cooling system, and, finally, the optical unit with the flash lamps. PL is another non-thermal technology with powerful applications to sterilize the grape surface, thus enabling the control of microbial loads and, therefore, facilitating the use of selected starters and the reduction of SO2 levels in wines.

Emerging non-thermal technologies open new possibilities in winemaking technology, generally facilitating at the same time the control of indigenous microorganisms and the use of new biotechnologies such as the fermentation with non-*Saccharomyces* yeasts or the use of yeast-bacteria co-inoculations. Most of them (HHP, UHPH, PEF, eBeam, and US) also facilitates a faster extraction of phenolic compounds from the grape skins, including not only pigments and tannins, but also aromatic and flavor compounds, thus reducing the maceration times. Several of them (UHPH, PEF, US, and PL) can be applied in a continuous mode when the crushed grape or must is pumped to the fermentation tank, increasing the processing yield and reducing the dead times. Some of these technologies, such as UHPH, produce an intense inactivation of oxidative enzymes, preserving better the sensory quality and strongly reducing the SO2 needs. Finally, most of these technologies

have low energetic requirements, so the running costs are moderated.

This research was funded by Ministerio de Ciencia, Innovación y Universidades grant number [RTI2018-096626-B-I00] and by European Regional Development Fund (ERDF) through the National Smart Growth Operational Programme FEDER INTERCONECTA grant number [EXP-00111498/ITC-20181125], project:

*DOI: http://dx.doi.org/10.5772/intechopen.92035*

**8. Conclusions**

**Acknowledgements**

FRESHWINES.

*Emerging Technologies to Increase Extraction, Control Microorganisms, and Reduce SO2 DOI: http://dx.doi.org/10.5772/intechopen.92035*

and cell walls can be observed by electronic microscopy, and it is associated to a higher concentration of eluted protein [60]. These effects affect vegetative and spore forms of microorganisms. *Saccharomyces* and non-*Saccharomyces* yeasts and lactic acid bacteria are controlled in grapes at low temperature and without effect in external appearance and sensory quality of food [60] (**Figure 16**).

Currently, PL devices not only for continuous food treatment, but also for the sterilization of food packaging are available [61]. The PL equipment is formed by an electronic module containing both control and monitoring systems, high voltage components for the flashing lamps, cooling system, and, finally, the optical unit with the flash lamps. PL is another non-thermal technology with powerful applications to sterilize the grape surface, thus enabling the control of microbial loads and, therefore, facilitating the use of selected starters and the reduction of SO2 levels in wines.
