title: Effect of nitrogen flushing and storage temperature on flavor and shelf-life of whole milk powder.
abstract: The US industry standard for shelf-life of whole milk powder (WMP) is 6 to 9 mo, although previous research has demonstrated flavor changes by 3 mo at ambient storage. This study evaluated the influence of packaging atmosphere, storage temperature, and storage time on WMP shelf-life using sensory and instrumental techniques. Two commercial batches of WMP were repackaged in plastic laminate pouches with air or nitrogen and stored at 2 degrees C or 23 degrees C for 1 yr. Descriptive analysis was conducted using a 10-member trained panel; volatile analysis was performed using solid-phase microextraction with gas chromatography-mass spectrometry. Consumer acceptance (n = 75) was conducted every 3 mo with reconstituted WMP and white and milk chocolate made from each treatment. Data were analyzed using ANOVA with Fisher's LSD, Pearson correlation analysis, and principal component analysis. Air-stored WMP had higher peroxide values, lipid oxidation volatiles, and grassy and painty flavors than nitrogen-flushed WMP. Storage temperature did not affect levels of straight chain lipid oxidation volatiles; 23 degrees C storage resulted in higher cooked and milkfat flavors and lower levels of grassy flavor compared with 2 degrees C storage. Consumer acceptance was negatively correlated with lipid oxidation volatiles and painty flavor. Nitrogen flushing prevented the development of painty flavor in WMP stored up to 1 yr at either temperature, resulting in chocolate with high consumer acceptance. Nitrogen flushing can be applied to extend the shelf life of WMP for use in chocolate; storage temperature also plays a role, but to a lesser extent.
authors.affiliation: Department of Food, Bioprocessing and Nutritional Sciences, Southeast Dairy Food Research Center, North Carolina State University, Raleigh 27694, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Lloyd
authors.forename: S J
authors.initials: SJ
authors.lastname: Hess
authors.forename: M A
authors.initials: MA
authors.lastname: Drake
mesh_terms: D000328:Adult; D000818:Animals; D002099:Cacao / Q000592:standards; D003116:Color; D005511:Food Handling / Q000379:methods*; D005524:Food Technology; D006801:Humans; D008875:Middle Aged; D008892:Milk / Q000737:chemistry / Q000592:standards*; D009584:Nitrogen / Q000737:chemistry*; D010100:Oxygen / Q000032:analysis; D010545:Peroxides / Q000032:analysis; D025341:Principal Component Analysis; D013649:Taste; D013696:Temperature; D055815:Young Adult
chemical_list: D010545:Peroxides; D009584:Nitrogen; D010100:Oxygen