New Technology For Grape Storage
“To produce and commercialise very high quality grapes in the most profitable and sustainable way” is the mission statement of Agrivale, a leading table grape producer based in the São Francisco River Valley in the north east of Brazil. Founded in 1996, the company has built a reputation not only for developing and producing crunchy, flavoursome grapes but also for maintaining a balanced, ethical relationship with employers, suppliers and the natural environment.
Worldwide demand for table grapes has been growing in recent years, as disposable incomes have risen and dietary habits have changed to include more fresh fruit. Grapes contain a wide range of nutrients, in particular vitamins C and K, and they are high in antioxidants, which help repair damaged cells and may prevent chronic diseases.
Technological advances in the way that grapes are stored have also contributed to the growth of the market, and in March 2021, Agrivale invited Güntner to retrofit the air coolers in its grape cold store chamber, which had originally been built 18 years previously. The 2,160 cubic-metre chamber is used for storing around 250 tonnes of fruit at a temperature between 0°C and -0.5°C.
“The grape produced in the São Francisco Valley is a very sensitive fruit with high added value,” says Luciano Costa, Güntner’s Technical Sales Representative in Brazil. “The stability of the ambient temperature and humidity of the air were key factors that needed to be considered in the project, with the objective of guaranteeing the necessary cold quality to obtain excellence in the final product.”
But temperature wasn’t the only consideration. As is traditionally the case in grape production, sachets of sodium metabisulphite are used in the chamber. This salt reacts with water, generating sulphur dioxide, and keeps the fruit free from fungus. But over time the chemical had caused corrosion in the existing heat exchanger.
“So our effort wasn’t only directed at the air cooler,” says Costa.
Six Güntner Cubic VARIO Air Coolers were installed, which use less ammonia than the previous heat exchangers and are also lighter and more compact. Furthermore, the stainless steel coil tubes and the air coolers’ epoxy fin are ideal for resisting the corrosive chemical elements in the chamber’s atmosphere. Exclusively designed fans for Güntner were used for air circulation in the chamber, and an insulated basin was also included to prevent condensation, together with an aluminium-magnesium alloy fairing, covered with white epoxy powder paint.
According to Ramon Barbosa, the Operation General Manager at Agrivale, the Güntner cooling solution has worked perfectly. “We are very happy with the performance of the cold room, from the finishing of the air coolers, which have an excellent visual appeal, to the ambient noise level,” he says.
“The temperature history shows stability and significant improvement in the cold air,” he adds. “The formation of ice on the equipment has been greatly reduced, compared to the previous cooling solution; and as a result, the de-icing efficiency has increased. After putting the chamber into operation, we monitored performance during a specified period and the quality of the cooling system was so high that we now use the same environment for our export grapes.”