Volatile component change in whey protein concentrate during storage investigated by headspace solid-phase microextraction gas chromatography

Abstract

-Whey protein concentrate (WPC) is a nutritious ingredient and has gained popularity to be used in many traditional and novel food products. It typically has a shelf-life of 9 to 18 months when stored at room temperature. Fresh manufactured WPC could have a bland or slightly dairy, whey flavor. However, recognizable off-flavor can be developed during storage and this off-flavor becomes one of the major factors limiting its application in delicate formula. To understand the off-flavor development during the storage, WPC 80 and Instantized WPC 80 samples were stored at 35, 40 and 45 • C for a period of 15 weeks. Selected volatile compounds including dimethyl disulfide, pentanal, hexanal, heptanal, 2-heptanol, 2-octanone, octanol, 1-octen-3-ol, 1-nonanol and 2-nonanol were analyzed using headspace solid-phase microextraction gas chromatography. The results showed that the concentrations of most of these compounds considerably increased during storage, especially when stored at 45 • C. Instantized WPC showed higher lipid oxidation compounds than regular WPC while removal of oxygen reduced their formation.whey protein concentrate / volatile formation / solid phase microextraction / gaschromatography Résumé -Variation des composés volatils dans des concentrés de protéines de lactosérum au cours du stockage suivie par chromatographie en phase gazeuse après microextraction en phase solide. Le concentré de protéines de lactosérum (CPL) est un ingrédient nutritif de plus en plus utilisé dans de nombreux produits alimentaires traditionnels ou nouveaux. Conservé à tempé-rature ambiante, il a une durée de vie de 9 à 18 mois. Juste après fabrication, le CPL a une flaveur fade ou légèrement laitière de lactosérum. Cependant des défauts de flaveur peuvent se dévelop-per au cours du stockage et devenir un facteur limitant majeur pour son utilisation ultérieure dans des formules délicates. Pour comprendre le développement de défauts de flaveur au cours du stockage, des échantillons de CPL 80 et de poudre de CPL 80 (poudre sous atmosphère d'oxygène ou non), ont été stockés à 35, 40 et 45 • C sur une période de 15 semaines. Des composés volatils sélectionnés (disulfure de diméthyl, pentanal, hexanal, heptanal, 2-heptanol, 2-octanone, octanol, 1-octen-3-ol, 1-nonanol et 2-nonanol) ont été analysés par chromatographie en phase gazeuse après microextraction en phase solide. Les résultats ont montré que les concentrations de la plupart de ces composés augmentaient au cours du stockage, surtout à 45 • C. Il se formait plus de composés d'oxydation des lipides dans les poudres de CPL que dans le CPL, cependant plus faiblement en l'absence d'oxygène. concentré de protéines de lactosérum / composé volatil / microextraction en phase solide / chromatographie en phase gazeuse Abbreviations: WPC: regular 80% whey protein concentrate; HS: head space; SPME: solid phase microextraction; GC: gas chromatography; MS: mass spectrometry; HPLC: high performance liquid chromatography; FID: flame ionization detector; RI: retention index.

The Impact of Agglomeration and Storage on Flavor and Flavor Stability of Whey Protein Concentrate 80% and Whey Protein Isolate

“…These results suggest that degradation has occurred in whey proteins, regardless of agglomeration treatment by this time. Javidipour and Qian (2008) found similar results during an accelerated storage study. Their research also showed that hexanal and heptanal concentrations initially increased in WPC80 followed by a subsequent decrease during storage.…”

“…However, to our knowledge, few studies have addressed stability of WPC80 or WPI or the impact of agglomeration on the flavor and flavor stability of WPC80 and WPI. Javidipour and Qian (2008) evaluated instantized and noninstantized WPC80 from a single manufacturer under accelerated storage conditions and documented increases in relative abundance of selected volatile compounds including a range of aldehydes, suggestive of lipid oxidation. They observed that instantized product developed lipid oxidation products faster than noninstantized product.…”

Volatile compounds of Van Herby cheeses produced with raw and pasteurized milks from different species

“…The Flame Ionization Detector (FID) temperature was 270°C. All of the samples were analyzed in triplicate, and the same fiber was used for the entire experiment (Javidipour and Qian 2008). IS peak area ratio was used as an arbitrary unit for calculating the quantities of each volatile compound.…”

“…The instrument control and data analysis were performed using enhanced Chemstation software (Agilent Technologies, Inc., Santa Clara, CA, USA). Peak identification of volatiles was based on comparison of the MS spectra with the Wiley7n and Flavor2 libraries and with the spectra of injected standards as well as on the retention times of the standards (Javidipour and Qian 2008).…”

From high milk protein powders to the rehydrated dispersions in variable ionic environments: A review

“…WPC powders that contain between 35% and 55% of proteins are mainly used in animal feed manufacture (Onwulata et al, 2003;Yun et al, 2005). Commercial WPC develops off flavor during storage and this problem is one of the major factor limiting its applications in delicate formula (Javidipour and Qian, 2008;Liaw et al, 2010). Two mechanisms (lipids oxidation and Maillard browning) are supposed to be the main causes of off flavor (Whitfield, 1992).…”