Environmental assessment of ultra-high pressure homogenisation for milk and fresh cheese production
Author
Valsasina, Lucia
Term
4. Term
Publication year
2015
Submitted on
2015-06-03
Pages
71
Abstract
Mejeriprodukter står for cirka 8–10% af miljøpåvirkningerne fra europæisk forbrug (Weidema et al., 2009). Samtidig er virksomheder under pres for at levere højere kvalitet til konkurrencedygtige priser. Dette studie undersøger ultrahøjtryks-homogenisering (UHPH) til komælk—en ny steriliseringsteknologi, der arbejder ved tryk op til 400 MPa—som alternativ til den almindelige kombination af ultrahøj temperatur (UHT) og homogenisering. Fordi UHPH samler sterilisering og homogenisering i ét trin, forventes den at give samme eller bedre kvalitet med lavere energiforbrug. For friskost har UHPH-behandlet mælk vist længere holdbarhed fra cirka 13 til 19 dage og højere udbytte fra omkring 11% til 14% (Escobar, 2011; Zamora og Guamis, 2014). Vi gennemfører en livscyklusvurdering (LCA)—en miljøvurdering fra forarbejdning til bortskaffelse—af UHPH- og UHT-behandling af mælk og den friskost, der fremstilles heraf. Pilotskaladata blev indsamlet for: UHPH-udstyr med kapacitet 90 l/t testet med vand, buffer, skummet mælk (1,5%) og sødmælk (3,5%); UHPH på 360 l/t med vand; samt et indirekte UHT-system på 85 l/t med forudgående homogenisering, testet med vand. Da det første forsøg viste ingen forskel i energiforbrug mellem de fire væsker, blev kun vand brugt i de efterfølgende tests. Fordi UHPH endnu ikke anvendes industrielt, blev potenssammenhænge brugt til at modellere relationen mellem kapacitet og energiforbrug ved opskalering. På pilotskala viste UHPH lavere vand- og energiforbrug og dermed miljøfordele; elforbruget alene var cirka 14% lavere. På industriel skala kan nuværende UHT-systemer dog genvinde omkring 90% af energien, et niveau UHPH næppe når med dagens teknologi. Alligevel har UHPH potentiale til mindst 43% reduktion i energiforbrug og CO2-udledning med mulighed for yderligere reduktioner på længere sigt, og teknologien kan også forbedre mælkekvaliteten. Opskalering viste øget effektivitet mellem pilotsystemer og bekræftede en lineær sammenhæng mellem energiforbrug, kapacitet og hastighed for UHPH-homogenisatorer. Den længere holdbarhed af friskost fremstillet af UHPH-mælk kan give fordele i større skala ved at reducere madspild og ressourceforbrug.
Dairy products account for about 8–10% of the environmental impacts of European consumption (Weidema et al., 2009). At the same time, companies are under pressure to deliver higher quality at competitive prices. This study examines ultra-high pressure homogenisation (UHPH) for cow’s milk—an emerging sterilisation method that uses pressures up to 400 MPa—as an alternative to the conventional combination of ultra-high temperature (UHT) treatment and homogenisation. Because UHPH combines sterilisation and homogenisation in a single step, it is expected to match or exceed product quality while using less energy. In fresh cheese, milk treated with UHPH has been shown to increase shelf life from roughly 13 to 19 days and raise yield from about 11% to 14% (Escobar, 2011; Zamora and Guamis, 2014). We conduct a life cycle assessment (LCA)—an environmental assessment from processing through end-of-life—of UHPH and UHT milk processing and the fresh cheese made from them. Pilot-scale data were collected for: UHPH equipment with a capacity of 90 l/h tested with water, buffer, skimmed milk (1.5%), and whole milk (3.5%); UHPH at 360 l/h with water; and an indirect UHT system at 85 l/h, including upstream homogenisation, tested with water. Because the first case showed no difference in energy use across the four liquids, later tests used only water. As UHPH is not yet used industrially, power-law models were applied to relate capacity and energy use as scale increases. At pilot scale, UHPH showed lower water and energy use, leading to environmental benefits; electricity consumption alone was about 14% lower. At industrial scale, however, current UHT systems can recover around 90% of energy, a level that UHPH is unlikely to achieve with today’s technology. Even so, UHPH has the potential to reach at least 43% reductions in energy use and carbon dioxide emissions, with further reductions possible over the longer term, and it may also improve milk quality. Upscaling indicated increased efficiency across pilot units and confirmed a linear relationship between energy use, capacity, and speed for UHPH homogenisers. The longer shelf life of fresh cheese made from UHPH milk could deliver larger-scale benefits by reducing food waste and resource use.
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