title: Potassium sorbate reduces production of ethanol and 2 esters in corn silage.
abstract: The objective of this work was to evaluate the effects of biological and chemical silage additives on the production of volatile organic compounds (VOC; methanol, ethanol, 1-propanol, methyl acetate, and ethyl acetate) within corn silage. Recent work has shown that silage VOC can contribute to poor air quality and reduce feed intake. Silage additives may reduce VOC production in silage by inhibiting the activity of bacteria or yeasts that produce them. We produced corn silage in 18.9-L bucket silos using the following treatments: (1) control (distilled water); (2) Lactobacillus buchneri 40788, with 400,000 cfu/g of wet forage; (3) Lactobacillus plantarum MTD1, with 100,000 cfu/g; (4) a commercial buffered propionic acid-based preservative (68% propionic acid, containing ammonium and sodium propionate and acetic, benzoic, and sorbic acids) at a concentration of 1 g/kg of wet forage (0.1%); (5) a low dose of potassium sorbate at a concentration of 91 mg/kg of wet forage (0.0091%); (6) a high dose of potassium sorbate at a concentration of 1g/kg of wet forage (0.1%); and (7) a mixture of L. plantarum MTD1 (100,000 cfu/g) and a low dose of potassium sorbate (91 mg/kg). Volatile organic compound concentrations within silage were measured after ensiling and sample storage using a headspace gas chromatography method. The high dose of potassium sorbate was the only treatment that inhibited the production of multiple VOC. Compared with the control response, it reduced ethanol by 58%, ethyl acetate by 46%, and methyl acetate by 24%, but did not clearly affect production of methanol or 1-propanol. The effect of this additive on ethanol production was consistent with results from a small number of earlier studies. A low dose of this additive does not appear to be effective. Although it did reduce methanol production by 24%, it increased ethanol production by more than 2-fold and did not reduce the ethyl acetate concentration. All other treatments increased ethanol production at least 2-fold relative to the control, and L. buchneri addition also increased the 1-propanol concentration to approximately 1% of dry matter. No effects of any treatments on fiber fractions or protein were observed. However, L. buchneri addition resulted in slightly more ammonia compared with the control. If these results hold under different conditions, a high dose of potassium sorbate will be an effective treatment for reducing VOC production in and emission from silage. Regulations aimed at reducing VOC emission could be ineffective or even increase emission if they promote silage additives without recognition of different types of additives.
authors.affiliation: University of Southern Denmark, Institute of Chemical Engineering, Biotechnology and Environmental Engineering, Odense M 5230, Denmark. Electronic address: saha@kbm.sdu.dk.
authors.forename: Sasha D
authors.initials: SD
authors.lastname: Hafner
authors.affiliation: Department of Land, Water and Air Resources, University of California, Davis, One Shields Avenue, Davis 95616.
authors.forename: Roberta B
authors.initials: RB
authors.lastname: Franco
authors.affiliation: Department of Animal and Food Sciences, University of Delaware, Newark 19716.
authors.forename: Limin
authors.initials: L
authors.lastname: Kung
authors.affiliation: USDA Agricultural Research Service, Pasture Systems and Watershed Management Research Unit, 3702 Curtin Rd., University Park, PA 16802.
authors.forename: C Alan
authors.initials: CA
authors.lastname: Rotz
authors.affiliation: Department of Animal Science, University of California, Davis, One Shields Avenue, Davis 95616.
authors.forename: Frank
authors.initials: F
authors.lastname: Mitloehner
mesh_terms: D000433:1-Propanol / Q000378:metabolism; D000821:Animal Feed; D000818:Animals; D001419:Bacteria / Q000737:chemistry / Q000187:drug effects; D004043:Dietary Fiber; D004952:Esters / Q000378:metabolism; D000431:Ethanol / Q000378:metabolism*; D007778:Lactobacillus / Q000737:chemistry / Q000187:drug effects; D012820:Silage / Q000032:analysis* / Q000382:microbiology; D013011:Sorbic Acid / Q000494:pharmacology*; D055549:Volatile Organic Compounds / Q000378:metabolism*; D015003:Yeasts / Q000737:chemistry / Q000187:drug effects; D003313:Zea mays
chemical_list: D004043:Dietary Fiber; D004952:Esters; D055549:Volatile Organic Compounds; D000431:Ethanol; D000433:1-Propanol; D013011:Sorbic Acid
keywords: ethanol; potassium sorbate; silage; volatile organic compound