ANTIGRO - New strategies for sprout control in long time storage of processing potatoes

To achieve optimal fry color and low acrylamide levels, processing potatoes must be stored at a slightly higher storage temperature than is otherwise optimal to avoid sprouting. It is therefore necessary to introduce measures to prevent sprouting during long-term storage. In this project, new, robust and sustainable strategies will be developed for long-term storage of potatoes for frying, as an alternative to the sprout suppressant (CIPC) which is now abandoned in the EU and Norway. The strategies must be adapted to the various potato varieties, stores and ventilation systems used in Norway. In three storage seasons (2020-2023), large-scale testing has been carried out with different treatment strategies with sproutsuppressants. The test was carried out in 6 different commercial stores with different types of storage systems. Sprout suppression was more og less successful with all types of ventilation system. Three different sproutsuppressors were tested: 1,4 sight, Biox-M (green mint oil) and Argos (orange oil). Different strategies were tested with different doses and combinations of chemicals. The potato varieties Innovator, Lady Claire, Kiebitz, Lady Britta and Oleva were included in the trials. All stores were monitored with temperature, RH and CO2 logging. As expected, it turned out that the CO2 level rises a lot during treatment when the stores are closed to intake of outside air for 48-72 hours. After the end of storage, the potatoes were assessed for quality. There were no differences between different treatment strategies when it came to weight loss, dry matter, silver scurf and frycolour. All treatment strategies had a sprout inhibiting effect. 1,4 sight has a good effect and it can be considered to reduce the number of treatments and doses in seasons where the potato is not physiologically mature at the time of harvest. For Biox-M and Argos, it is important to hit the right time for treatment as they are most effective when tubers have already sprouted. Large-scale testing continues in the 2024-2025 storage season. A survey of 13 selected stores has been carried out to identify commercial stores that are suitable for sproutsuppression treatment with volatile gases. Consideration has been given to building measurements, stacking solutions (boxes), ventilation system and construction in relation to distribution of sproutsuppressor with hot fog around boxes/potatoes and possible leakage/gas diffusion. This test was carried out during the storage season using a smokemachine. Appropriate adjustments have been made in the stores where necessary, to obtain the best possible results from the sprout suppression treatment. It is planned to continue the survey in 2025. Since 2021, residue analysis for chlorpropham has been carried out annually in tubers from selected potatostores that were previously treated with this agent. There were residual values between 0 and 0.54 mg/kg in the tested warehouses. Measures are being taken to bring down residuals in the stores. Residue analysis will continue in the 2024-25 season. Controlled storage trials have been carried out in small-scale experimental stores with testing of 5-6 different treatment strategies in 2 storage seasons, 2021-2023. Various doses of 1,4 sight, Biox-M and Argos were tested. The strategies are tested on various potato varieties (Peik, Innovator, Fontane, Oleva, Linus and G07-1655) and Lady Claire and Kiebitz. In addition, material with different degrees of maturity has also been tested. The trials have shown that there is a sprout-inhibiting effect of all tested agents. 1,4 sight has proven to be the most effective chemical even with reduced doses and also in the least dormant varieties. The experiments have shown that it is important to hit the right time for treatment with Biox-M and Argos in order to have a good effect and that it is important to follow up with several treatments if the potato is to be stored for a long time. Low temperature during storage will reduce sprouting, but low temperature storage increase the risk for accumulation of reducing sugars. The project investigates whether storage at low temperatures (4 C and 6 C) can to some extent replace treatment with sprout suppressors. A small-scale trial was carried out in several varieties (Innovator, Peik, Fontane, G07-1655, L. Claire, Kiebitz and P03-19-21). Low temperature storage reduced sprouting in all varieties. The crisp varieties Kiebitz and Lady Claire stand out as varieties that manage to be stored at a low temperature without accumulating reducing sugars.

Potetindustribedriftene Findus Norge, Maarud, Hoff og Orkla/Kims har i dag tilnærmet helårsproduksjon av friterte potetprodukter (chips/pommes frites) med basis i norske poteter. Friteringspoteter kan av kvalitetshensyn (farge, akrylamid) ikke lagres kaldt. Ved helårs produksjon, både i Norge og andre land, er det derfor helt nødvendig å bruke midler som hindrer potetene i å spire på lager på etterjulsvinteren. Norsk og Europeisk friteringsbransje står nå i en svært krevende situasjon, etter et forbud mot det eneste middelet som til nå er brukt i Norge. Alternativer finnes, men midlene er kostbare, og krever utprøving i forhold til våre særegne norske råvarer (sorter, fysiologisk kvalitet) og lagringsfasiliteter. Utvikling av nye, kvalitetsmessig robuste strategier for å redusere groing er nødvendig for at langtidslagringen kan gjennomføres med tilstrekkelig forutsigbarhet og uten for stor risiko. Behandlingen må være økonomisk bærekraftig og være tilpasset de sorter, råvarekvaliteter og lagerforhold som er vanlig her i landet. Målet med prosjektet er en nasjonal satsing for å sikre grunnlaget for norsk dyrking og videreforedling av de ca 30.000 tonn poteter som bedriftene i dag behandler med spirehemmer. Uten tilstrekkelig tilpassing kan alternativet bli redusert norsk potetproduksjon og økt import av antigrobehandlet potet, og redusert driftssesong og/eller lønnsomhet for bedriftene. Prosjektet skal, i samarbeid med internasjonal ekspertise, utvikle nye og robuste behandlingsstrategier med best mulig økonomisk og kvalitetsmessig resultat etter langtidslagring, tilpasset de lagertypene som brukes i Norge. Det skal også undersøkes en hypotese om at mindre fysiologisk modne poteter (som i Norge) krever mindre bruk av antigromiddel enn mer modne potetene lenger sør i Europa. Videre skal det fokuseres på reduksjon av mengde uønskede reststoffer av antigromidler i potet, og på alternative strategier for langtidslagring uten, eller med svært lave doser av antigromidler