The use of lactoperoxidase for the bleaching of fluid whey

Abstract

Lactoperoxidase (LP) is the second most abundant enzyme in bovine milk and has been used in conjunction with hydrogen peroxide (H₂O₂) and thiocyanate (SCN⁻) to work as an antimicrobial in raw milk where pasteurization is not feasible. Thiocyanate is naturally present and the lactoperoxidase system purportedly can be used to bleach dairy products, such as whey, with the addition of very little H₂O₂ to the system. This study had 3 objectives: 1) to quantify the amount of H₂O₂ necessary for bleaching of fluid whey using the LP system, 2) to monitor LP activity from raw milk through manufacture of liquid whey, and 3) to compare the flavor of whey protein concentrate 80% (WPC80) bleached by the LP system to that bleached by traditional H₂O₂ bleaching. Cheddar cheese whey with annatto (15 mL of annatto/454 kg of milk, annatto with 3% wt/vol norbixin content) was manufactured using a standard Cheddar cheesemaking procedure. Various levels of H₂O₂ (5-100 mg/kg) were added to fluid whey to determine the optimum concentration of H₂O₂ for LP activity, which was measured using an established colorimetric method. In subsequent experiments, fat-separated whey was bleached for 1h with 250 mg of H₂O₂/kg (traditional) or 20 mg of H₂O₂/kg (LP system). The WPC80 was manufactured from whey bleached with 250 mg of H₂O₂/kg or 20mg of H₂O₂/kg. All samples were subjected to color analysis (Hunter color values and norbixin extraction) and proximate analysis (fat, protein, and moisture). Sensory and instrumental volatile analyses were conducted on WPC80. Optimal LP bleaching in fluid whey occurred with the addition of 20mg of H₂O₂/kg. Bleaching of fluid whey at either 35 or 50°C for 1 h with LP resulted in > 99% norbixin destruction compared with 32 or 47% destruction from bleaching with 250 mg of H₂O₂/kg, at 35 or 50°C for 1 h, respectively. Higher aroma intensity and increased lipid oxidation compounds were documented in WPC80 from bleached whey compared with WPC80 from unbleached whey. Monitoring of LP activity throughout cheese and whey manufacture showed that LP activity sharply decreased after 30 min of bleaching (17.01 ± 1.4 to < 1 U/mL), suggesting that sufficient bleaching takes place in a very short amount of time. Lactoperoxidase averaged 13.01 ± 0.7 U/mL in unpasteurized, fat-separated liquid whey and 138.6 ± 11.9 U/mL in concentrated retentate (11% solids). Lactoperoxidase may be a viable alternative for chemical whey bleaching.

The effect of microfiltration on color, flavor, and functionality of 80% whey protein concentrate

“…Consistent with oxidative reactions, HP bleaching and LP bleaching decreased cooked or milky flavor and increased cardboard flavor in WPC80, consistent with previous studies (Jervis et al, 2012;Campbell et al, 2012). Both bleached WPC80 displayed cabbage flavor, which was not detected in control and MF WPC80.…”

“…These samples were tempered to 20°C and served at this temperature. Eight trained panelists (23-45 yr old, each with over 150 h of experience with descriptive analysis of dried dairy ingredient aroma and flavor) evaluated the rehydrated powders using a 0-to 15-point intensity scale and the Spectrum method (Meilgaard et al, 1999) and an established sensory lexicon (Wright et al, 2009;Campbell et al, 2012;Jervis et al, 2012). Panelists were instructed to expectorate samples after evaluation.…”

“…The strong oxidizing capacity al-lows OSCNto react with carotenoids, leading to color loss of norbixin. Campbell et al (2012) demonstrated that the LP system with an optimal concentration of 20 mg of H 2 O 2 /kg was more effective than HP alone in norbixin destruction (bleaching >99%), but lipid oxidation products were also higher in concentration in LP-bleached whey compared with unbleached whey .…”

Sensory and Functionality Differences of Whey Protein Isolate Bleached by Hydrogen or Benzoyl Peroxide

“…Approximately 10% of the norbixin added to cheese milk partitions into the liquid whey and results in a yellow color in whey protein ingredients if it is not removed (Kang and others ; Smith and others ). Currently, benzoyl peroxide (BP) and hydrogen peroxide (HP) are the only two chemical bleaching agents approved by the FDA for bleaching of whey (US FDA ,b), although enzymatic alternatives to chemical bleaching also exist (Campbell and others , ), and alternate coloring agents are also being developed and marketed (Chr Hansen ).…”

Laktoperoksidaz Sistem Aktivasyonunun Çiğ Sütün Mikrobiyolojik Kalitesi Üzerine Etkileri

“…The LP system consists of three major components, including lactoperoxidase enzyme, thiocyanate ion (SCN-) and hydrogen peroxide (H 2 O 2 ). The LP system becomes completely active when these three components come together [9] . The enzyme in the presence of H 2 O 2 , catalyzes oxidation of thiocyanate (SCN-) to form an intermediate product hipothiocyanate, which exhibits bactericidal or bacteriostatic effect on the bacteria [10] .…”