Put the grapes in a high-humidity and pre-cooling state in time: a way to avoid dry stems

2021-11-11 07:11:53 By : Ms. Karen Swift-Corp

Jan Lievens of UTE Applied Postharvest Technologies said that the dry stem problem in the table grape industry is well known, but he believes it can also be avoided.

He mentioned the speech on South African grapes delivered by Oscar Salgado from SanLucar at the Global Grape Summit 2020. In his speech, Salgado pointed out that there are "strong differences" between the fruits in this field compared to the fruits it arrives. The stem (shaft) is named as the technological challenge to South African industry.

Jan added that the appearance of the grapes this season is more prominent because of the slower sales and the longer storage time of the grapes upon arrival. 

Zero declaration for dry stems on Berg River farms Last year, his method helped Pieter Badenhorst to obtain zero quality declarations for its raisins stems at the Leeuwenhoek farm in Vendutiekraal Boerdery in Halfmanshof near Porterville in the Berg River region, most of which were used in the steri market, involving Long travel.

Lucas Badenhorst, his brother and partner of Vendutiekraal Boerdery, farms in the Hex Valley and has been successfully running the system for many years. He cautioned that this is not just a question of buying equipment, the problem of stems is a thing of the past.

"This is not the gold bullet proposed by Jan, but the overall approach you must accept," Lucas explained. The major change in the farm agreement is to pre-cool or receive the cut grapes from the vineyard within 20 to 30 minutes. 

Jan admits that this is not always easy. In fact, this means that the farm must adapt to smaller and more frequent trips between the vineyard and the packaging plant. Pieter said they managed to transport the grapes from the furthest point of the vineyard into the pre-cooling in at most half an hour; early last week, they started a new harvest on their farm.

"When you see the results, the changes needed to introduce grapes become self-evident," Lucas pointed out.

In some places in Cape Town, the temperature during grape picking may be close to 40°C. The warm air blowing through the crates will speed up the drying process. Therefore, under Jan’s system, if the temperature is too high, the picking will not proceed. Harvest (he recommends picking at a temperature between 18 and 28°C), and the grapes will never be transported on a truck without a cover.

"It makes sense," Pieter Badenhorst points out, "to avoid moisture loss from the stem."

Photo courtesy of Jan Lievens

The stem speed is 15 times faster than that of berries. In the pre-cooling stage, the field temperature is reduced to 95% relative humidity, which "to calm down the fruit", as Jan said, the temperature to the packaging plant is (17 – 22°C) and 80%. % Relative humidity. The BIOTurbo filter installed by Jan removes bacteria from the air; it has been expanded to a system used in packaging plants to remove stale air and bacteria and ensure sufficient air flow to reduce the risk of Covid infection in packaging plants. 

Jan said that it was this early stage that received too little attention, which confuses him. "It's a way of thinking about how to deal with crops. When you consider that the last 5% you can do brings you 99% of your income, it will focus very well," Jan said. "If the grapes stay warm for too long before packaging, you will be damaged and you will get brown and dry stems."

He explained that the stems are 15 times faster than berries, and they contain less sugar and are more susceptible to cold damage. In the packaging plant, under the condition of low relative humidity, excessive wind speed through the cooler will eventually lead to stems.  

"As long as the fruit is open to the atmosphere, we can make plans," Jan said. "And not just grapes, but also berries, apples and pears-I can still do something to make the fruit feel that it is part of the mother plant. The timing between 20 and 30 minutes is crucial, as is the pre-cooler. During this period, we heat it to the temperature to be packaged while removing bacteria from the air."

"When you cut the grapes, if the fruit stays warm for a long time, you may lose the entire crop within a few hours. Everything depends on the last 5% of the season. I find it strange that no more attention is devoted to it. above."

Jan conducted a UTE technology test on apples in a controlled atmosphere room. Compared with the controlled CA room, at the end of two months, there were 17% more apples from the room with UTE humidity system.

Jan found that due to water loss in the CA room, the content of apples and pears dropped by 10 to 15 cm.

“He installed the post-harvest technology with us two seasons ago in one of the best table grape producers in the Western Cape,” said Arnold Viljoen of Fruit IP Company TopFruit. “The results are spectacular. The quality of the fruit is greatly improved. , So that our TopFruit recommends this technology to all producers who grow our varieties."

Arnold added that in a world of growing production, the success of table grape producers will increasingly depend on the quality of the grapes upon arrival and their shelf life, and this technology may become the industry standard.

More information: Jan Lievens UTE Umhwebo Tel: 27 22 448 1002 Email: sales@umhwebo.com www.umhwebo.com

Publication Date: Thursday, January 7, 2021 Author: Carolize Jansen © FreshPlaza.com

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