Active packaging of UHT milk to prevent the development of stale flavour during storage

Abstract

Indirectly processed UHT milk was packaged in IntaseptTM aseptic pouches with (treatment) or without (control) oxygen-scavenging film and stored for 14 weeks at 26 ± 0.3°C. Samples were analysed at 0, 4, 8 and 14 weeks for dissolved oxygen, stale flavour volatiles (methyl ketones and aldehydes) and free fatty acids. Discriminative subjective analysis of odour by a consumer panel was also conducted. The oxygen-scavenging film was shown to significantly (p < 0.05) reduce dissolved oxygen content by 23-28% during storage. Significant reductions of 23-41% were also observed for some stale flavour volatiles, including three methyl ketones and two aldehydes. Free fatty acid levels remained far below threshold values, indicating that lipolytic rancidity would not interfere with the subjective analysis. However, the consumer panel failed to detect a significant difference in odour between the treatment and control samples. INTRODUCTIONUHT milk has been shown to have a flavour that is undesirable to many consumers. 1-3Some researchers attribute this mainly to the development of a 'stale' or 'oxidized' flavour defect that arises within a month of storage and increases in intensity as time progresses. [4][5][6] Lipid oxidation in the milk produces methyl ketones and saturated aldehydes which contribute to this stale flavour. [7][8][9][10][11] Initial concentrations of these carbonyl compounds are generally greater in UHT milk that has been indirectly processed rather than directly processed. 12Previous attempts at preventing stale flavour formation in UHT milk have included the addition of antioxidants such as ascorbic acid, 4 butylated hydroxy anisole (BHA) 6 and bioflavanoids. 13 An alternative is active packaging incorporating oxygen scavengers. In the past, this has usually been in the form of sachets inserted into the food package. For liquid foods it is preferable to have the scavenger incorporated into the package itself to allow for a greater contact surface with the product.14 Maloba et al. 15 have used an oxygenscavenging film containing polyfuryloxirane to improve the oxidative stability of sunflower oil. In other studies, a film containing a reducible organic compound was used to scavenge oxygen from yoghurt in order to improve the viability of probiotic bacteria, 16 and a similar oxygen-scavenging film was used to decrease the rate of ascorbic acid loss in orange juice. 17The aim of this investigation was to modify a commercially available aseptic package to include an oxygen-scavenging film, and monitor its effect on stale flavour volatiles during ambient storage when used to package indirectly UHT-processed full-cream milk. EXPERIMENTAL Preparation of packagingSample packaging consisted of Intasept TM (VisyPak, Melbourne, VIC, Australia) gusseted pouches (340 × 225 mm) comprising a metallized polyester(PET)/linear low-density polyethylene(LLDPE) outer web and a LLDPE inner web. Half of the pouches were modified to incorporate a prototype ZerO 2 TM oxygen scavenging film laminate (OSFL). The OSFL was inserted...

Active Packaging Applications for Food

“…In contrast, other applied metals, such as cobalt (Galdi and others ; Damaj and others ), act as a catalyst for the oxidation of polymers, or palladium (Yildirim and others ), that catalyzes the oxidation of hydrogen into water. Other systems that scavenge oxygen chemically include photosensitive dyes (Maloba and others ; Miller and others ; Zerdin and others ; Perkins and others ), ascorbic acid (Matche and others ; Pereira de Abreu and others ), gallic acid (Wanner ; Ahn and others ), or unsaturated fatty acids (Arvanitoyannis and Oikonomou ; Pereira de Abreu and others ). Moreover, there are also biochemical mechanisms that work through the use of enzymes (Andersson and others ; Fernández and others ; Kothapalli and others ; Nestorson and others ; Gohil and Wysock ), or biological approaches using bacterial spores (Anthierens and others ), or yeasts that are immobilized in a solid material (Edens and others ).…”

“…In ultra‐high temperature (UHT) milk, OS have been shown to prevent the development of stale flavor. Perkins and others () packaged indirectly processed UHT milk using packaging films containing a prototype ZerO 2 ™ OS film laminate. Thereby, the OS film significantly reduced the initial dissolved oxygen content of approximately 7 to approximately 3.8 mg/L during 14 wk of room temperature storage (26 °C), compared to the control with approximately 5 mg/L.…”

Milk Processing and Quality Management

“…Directly processed milk packaged in the plastic bottles exhibited quite high dissolved oxygen levels (5.8-7.2 mg L −1 ). The headspace volume can have a major influence on dissolved oxygen levels, and development of volatile carbonyl compounds caused by oxidation (Perkins et al, 2005(Perkins et al, , 2006.…”

Production and Evaluation of Type of Multi‐Layer Active Film for Packaging of Pasteurized Milk

“…Antimicrobial agents can be incorporated into a packaging system through simple blending with packaging materials, immobilization or coating differently depending on the characteristics of packaging system, antimicrobial agent and food. Due to the different antimicrobial mechanisms and the various physiologies of the microorganisms, each antimicrobial agent has different activity which affects microorganisms differently (Perkins et al, ; Del Nobile et al, ).…”