Title

Production and storage stability of liquid micellar casein concentrate.

Document Type

Abstract

Publication Date

2018

Publisher

American Dairy Science Association

Journal

Journal of Dairy Science

Volume

101

Issue

Suppl. 2

Pages

8

Language

en.

Keywords

microfiltration, micellar casein, shelf life

Abstract

Micellar casein is a high protein ingredient that can be used as a valuable source of intact casein in process cheese formulations. The objective of this study was to produce a highly concentrated micellar casein (HC-MC) and evaluate its storage stability. Skim milk was pasteurized at 72°C for 16 s and kept at ≤ 4°C until the following day when it was heated in a plate heat exchanger to 50°C and microfiltered with a ceramic GP MF system (0.1μm) in a feed and bleed mode to produce a 3 × MF retentate (1 kg of retentate:2 kg of permeate). Subsequently, the retentate was diluted 2× with soft-water (2 kg of water:1 kg of retentate) and again microfiltered at 50°C to a 3× concentration as described previously. The retentate was then cooled to 4°C, and stored overnight. The following day, the retentate was heated to 65°C and microfiltered in a recirculationmode until the total solid reached approximately 22%. Subsequently, the temperature was increased to 74°C and microfiltration was continued until the permeate flow rate reached less than 5 L/h. The HC-MC retentate was transferred at 74°C to sterilized vials and stored at 4°C. This trial was repeated 3 times using 3 separate batches of raw milk. During microfiltration, the mean cumulative SP removal in the first, second, and third stages was 46, 77, and 83%, respectively. The mean HC-MC at time zero contained 25.42% total solids (TS), 20.20% true protein (TP), 0.09% NPN, 0.55% NCN, 19.80% CN, 2.0% ash, 97.70% CN%TP, and 0.45% SP. The NCN content increased significantly (P < 0.05) from 0.55 to 0.76% during 2 mo of storage. The NPN also increased over time from 0.095% at time zero to 0.12% after 2 mo of storage. The mean aerobic bacterial count in HC-MC at time zero was 2.6 ± 0.16 log cfu/mL and increased to 3.5 ± 0.89 and 4.3 ± 0.97 log cfu/mL after 1 and 2 mo of storage, respectively. Coliform, yeasts, and mold were not detected at any time point. This study determined that HC-MC could be manufactured using ceramic MF membranes with over 25% TS and greater than 95% CN%TP. The impact of the small increase in NCN and NPN during 2 mo of storage on process cheese characteristics will be evaluated in subsequent studies.

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