Utilization of micellar casein in manufacture of clean label process cheese

1. Utilization of micellar casein in manufacture of clean label process cheese Ahmed Hammam Lloyd Metzger

2. Types of filtration MF UF NF RO Bacteria Fat Casein micelle Whey Protein Lactose Minerals Water 0.1 - 10.0 m 0.01 - 0.1 m Pore Size (Microns): 0.001 - 0.01 m <0.001 m Molecular Weight Cut-Off (Daltons): 1,000,000 Daltons 10,000 Daltons 1,000 Daltons 50 Daltons Operating Pressure (PSI): 5-30 PSI 15-150 PSI 100-500 PSI 250-1500 PSI

3. Casein – designed by nature as a packaging system for calcium and phosphate • 10,000 polypeptide chains of the four caseins • micro-granules of calcium phosphate • glyco-macro peptide portion on k-casein is concentrated on the surface • rennet coagulation - remove hairs Adapted from Adv. Prot. Chem – 1992, Holt 43:63-151

4. Categories of cheese • Rennet curd cheese • Acid curd cheese • Process cheese

5. Calcium and phosphate microgranules play a critical role in the aggregation of the casein micelle Calcium ions Ca2+ Phosphate ions Calcium phosphate complexes Organic phosphate

6. Rennet coagulation Stages • Primary phase – k-casein in hydrolyzed between 105th and 106th amino acid – net negative charges is removed from the surface of the micelle • Secondary phase – casein micelles aggregate and form a gel

7. Natural Cheese Structure Adapted from Kiely et al 1992 • The protein matrix contains embedded fat and moisture • Protein matrix is cross-linked by calcium and phosphate

8. What is process cheese? • Process cheese (PC) and process cheese products (PCP) are dairy foods prepared by blending dairy ingredients (such as natural cheese, protein concentrates, butter, non-fat dry milk, whey powder, and permeate) with nondairy ingredients (such as sodium chloride, water, emulsifying salts, color, and flavors) • Then heating the mixture with continuous agitation to produce a homogeneous product with an extended shelf-life

9. The principles of making PC & PCP O Na O P O Na Emulsifying salts hydrate, donate sodium ions and bind calcium ions O H O Natural cheese casein – calcium/phosphate cross-linked network O P O O Na+ Na+ H Heat and mixing induce interactions between the dispersed casein and fat Intact casein after heating and mixing Intact casein after interaction with emulsifying salts

10. Problem statement • Consumers perceive the emulsifying salts as chemicals, which reduce their acceptability for the PC and PCP • Emulsifying salts utilized in the typical PC and PCP increase the levels of sodium, which lead to high blood pressure • As a result, manufacture of PC and PCP without emulsifying salts would meet this consumer desire

11. Acid curd cheese (cottage cheese) • Milk can be clotted by lowering the pH to 4.6 (the isoelectric point of casein is 4.6 and casein becomes insoluble at pH 4.6) – this is how we make yogurt and cottage cheese • Warm milk at rest will form a gel similar to a rennet coagulated gel (slightly firmer, virtually all of the calcium and phosphate is solubilized, very small amount of syneresis) • Can also acidify at low temp with stirring to form a precipitate that can be separated by centrifugation (continuous process) • Can add acid directly or the acid can be produced by micro organisms (starter culture – can take 4 to 12 hours)

12. How is acid curd produced? Intact casein - calcium cross-linked network pH = 4.6 Starter cultures or acids Micellar casein concentrate (MCC) High level of casein bound calcium pH of 6.5-6.7 colloidal calcium phosphate complexes Acid curd cross-linked network

13. Process cheese without emulsifying salt? Gel formation during cooling Acid curd MCC Heat and mixing induce interactions between the dispersed casein and fat Intact casein after heating and mixing

14. Can micellar casein be used to make acid curd? • Acid curd can be produced from skim milk in a process similar to cottage cheese manufacture. It is also possible to produce acid curd from MCC • Making acid curd from MCC has advantages as compared to skim milk, since manufacturing MCC using microfiltration results in milk derived whey protein as a by-product which can be utilized in many applications, particularly making whey protein isolate (WPI) • In contrast, acid curd produced from skim milk results in acid whey as a by-product which is more difficult to utilize

15. Typical composition of MCC • The typical composition of MCC (3-stages using 3x concentration factor with a diafiltration) is > 9% true protein (TP) and > 13% solids • This MCC could be used immediately in making acid curd or diluted to lower protein levels prior for making acid curd if required

16. The hypothesis • We hypothesized that a ratio of 2 parts of protein from acid curd: 1 part of protein from MCC will create a partially deaggregated casein network similar to a typical process cheese that utilizes emulsifying salt • We also hypothesized that MCC can be used as an ingredient to produce acid curd

17. Objectives • The objectives of the study was: • To determine if PCP could be produced without emulsifying salt if a combination of acid curd and MCC are utilized in the formulation • To determine the optimum protein content of MCC for use in acid curd manufacture

18. 4 ͦC • TEMP: 50 ͦC (120 ͦF) • - Pressures: Rpi: 4 bar; Rpo: 2 bar; Ppo: 2 bar • Flux: 71.4 L/m2H • - CF: 3X Feed-bleed mode Manufacture of MCC using microfiltration (MF) Protein ~9%, TS~13%

19. Manufacturing of MCC powder • Part of this MCC was spray dried using a Niro-dryer to manufacture dried MCC • The rest of the MCC was utilized to produce acid curd • Adopted from Virtual Element Studios

20. Manufacturing of acid curd Water Liquid MCC MCC Addition of lactic acid Addition of lactic acid 9% MCC Addition of lactic acid 3% MCC 6% MCC 9% protein MCC 6% protein MCC 3% protein MCC pH=4.6 at 4°C Schematic manufacture of acid curd

21. The acidified MCC was then placed at 30°C water bath. The curd set at approximately 25°C, then it was cut and mixed gently during heating to 45°C • Subsequently, the whey was drained from the curd and the curd was pressed. After pressing, the curd was frozen until further analyses • The moisture adjusted yield of the acid curd was calculated. This experiment was repeated three times

22. PCP formulations Formulation programs -TechWizardTM Desired Final Properties Table 1. The targetedcomposition of process cheese products (PCP)

23. PCP formulations Table 2. Formulations utilized to manufacture process cheese product (PCP) 1Treatments: 3%= PCP made from acid curd that has been produced from 3% protein MCC; 6%= PCP made from acid curd that has been produced from 6% protein MCC; 9%= PCP made from acid curd that has been produced from 9% protein MCC

24. Process cheese manufacture • PCP formulations were prepared by mixing all ingredients in a kitechen aid at room temperature for 30 min to produce a homogenous paste

25. A 25 g sample of the paste was weighed in a canister and then cooked in a rapid visco analyzer (RVA) • The canisters were cooked in the RVA for 3 min at 95°C • The stirring speed was 1000 rpm during the first 2 min of the test and then it was decreased to 160 rpm during the last minute

26. Chemical and functional analyses • Total solids (TS), protein, ash, and pH of MCC and acid curd were determined before being utilized in PCP formulations • TS and pH of the final PCP were also determined

27. Apparent cooked viscosity • The cooked apparent viscosity of PCP was measured at 95 °C at the end of the cooking time in the RVA by calculating the mean of the last 5 values of viscosity

28. Speed Temperature Cooked viscosity Viscosity Measuring the apparent cooked viscosity of process cheese using the RVA

29. The hardness • 20 mm • 20 mm

30. The hardness of the PCP was measured by texture profile analysis (TPA) usingUniaxial double bite compression: • 50-mm diameter cylindrical flat probe (TA-25) • 10% compression • 1 mm/s crosshead speed

31. Force (g) Hardness Time (sec) Measuring the hardness of process cheese using the TPA

32. The melting temperature • The melting temperature was measured by using dynamic stress rheometer • The PCP was prepared by cutting the cheese into slices (2 mm thick) using a wire cutter • A stress sweep test of the PCP was performed at a frequency of 1.5 Hz and a stress ranged from 1 to 1000 Pa at 20°C using a rheometer with parallel plate geometry • The stress sweep experiment determined that the maximum stress limit for the linear viscoelastic region was 50 Pa

33. The melting temperature • The dynamic rheological properties of the PCP were then analyzed with a dynamic temperature ramp test that ranged from 20 to 90°C with a ramp rate of 1°C/min using a frequency of 1.5 Hz and a constant stress of 50 Pa • The temperature at which tan δ=1 (G′′/G′) was referred to as the cheese melting point

34. Melt temperature Storage modulus G' (Pa) Loss modulus G" (Pa) Temperature (°C) Measuring the melting point of process cheese using the DSR

35. Schreiber melt test • The PCP samples were cut into cylinders with a 28.5 mm diameter and 7 mm height (4 cylinders each ~5 g) and placed in Petri dishes • The dishes were transferred to a forced draft oven at 90°C for 7 min • The meltability of PCP samples was reported as the diameter of the melted cheese in millimeters (mm) • 28.5 mm

36. Statistical analysis • Statistical analysis was performed to study the effect of treatment (3, 6, and 9%) on the functional properties of PCP • The ANOVA test was done by using R software • Mean separation was done using the least significant difference (LSD) test • Significant difference at P < 0.05

37. Results and discussion Table 3. The composition of liquid and dry micellar casein concentrate (MCC)

38. Table 4. The composition of acid curd used in PCP formulations 100-actual%moisture Adjusted yield=actual yield x 100-desired%moisture 1Treatments: 3%= PCP made from acid curd that has been produced from 3% protein MCC; 6%= PCP made from acid curd that has been produced from 6% protein MCC; 9%= PCP made from acid curd that has been produced from 9% protein MCC a-cMeans in the same columnnot sharing a common superscript are different (P < 0.05)

39. Table 5. The composition of the PCP made from acid curd 1Treatments: 3%= PCP made from acid curd that has been produced from 3% protein MCC; 6%= PCP made from acid curd that has been produced from 6% protein MCC; 9%= PCP made from acid curd that has been produced from 9% protein MCC

40. Table 6. Thefunctional properties of the PCP made from acid curd 1Treatments: 3%= PCP made from acid curd that has been produced from 3% protein MCC; 6%= PCP made from acid curd that has been produced from 6% protein MCC; 9%= PCP made from acid curd that has been produced from 9% protein MCC

41. Conclusions 2 1 We determined that a ratio of acid curd protein to MCC protein of 2:1 created a partially deaggregated casein network that resulted in a process cheese with functionality similar to process cheese produced with emulsifying salts 3 No differences were detected in the functionality of PCP made from acid curd produced from 3-9% Acid curd could be made from MCC and used for manufacture a process cheese without emulsifying salt 4 The adjusted yield of acid curd significantly (P < 0.05) increased with protein content

42. Future work • Acid curd will be manufactured from MCC using starter culture • Evaluation of a continuous process that utilizes a decanter centrifuge instead of cheese vat to maximize the yield and increase the efficiency of acid curd manufacturing • Explore opportunities for exporting “cheese base in a bag”