Skim milk microfiltration before cheese making can concentrate the milk without retaining whey proteins. This study examined the effects of microfiltration at concentration factors of 1.3, 1.6, and 2.0 on the composition, yield, and aging of Cheddar cheese compared to a control. The results showed that protein recovery in the cheese increased with higher concentration factors as expected, while fat recovery was lower than 93% due to cream separation issues. Cheese yields increased with concentration factor but yield efficiencies remained similar to the control, indicating the process performs as predicted. Composition, pH, and proteolysis during aging were generally unaffected by microfiltration concentration.

1. Skim milk microfiltration: Impact on cheese composition, yield, and aging M. Neocleous, D. M. Barbano, and M. A. Rudan. Northeast Dairy Foods Research Center, 1 Cornell University, Ithaca, NY

2. Introduction Skim milk microfiltration can be used to remove milk serum proteins from milk prior to cheese making. The milk serum protein products will be superior to whey protein products and may have higher value.

3. This approach gives the same increase in concentration of milk casein and fat prior to cheese making as earlier approaches with UF. However, unlike UF, there is no attempt to retain whey proteins in the cheese to increase cheese yield. Introduction

4. While retention of whey proteins in cheese using UF increased cheese yield, it had negative impacts on cheese functionality (e.g., Mozzarella) and cheese flavor development during aging (e.g., Cheddar). Thus, UF has not been very successful for these two varieties of cheese. Introduction

5. Concentrating milk prior to cheese making with microfiltration (MF) should produce a cheese that has the same composition as cheese made without MF. Therefore, the cheese should have similar functionality and flavor development to control cheese. Hypothesis

6. To determine the influence of skim milk microfiltration on the composition and make procedure at 1.3, 1.6, and 2X concentration factors for aged Cheddar cheese. To determine if fat and protein recovery in the cheese and cheese yield efficiency are influence by microfiltration. To determine if proteolysis and cheese aging are influenced by microfiltration. Objectives

7. Experimental Design Trial 1 : 4 x 4 Randomized Block (n = 16) 1.0, 1.3, 1.6 and 2X concentration factor complete except for final aging data Trial 2 : Paired comparison of 1.0 and 2X to try to adjust make procedure of 2X to achieve similar aging to the control. (planned for winter 1999/2000)

8. Full-fat, milled-curd Cheddar cheese was made. Approximately, 220 kg of milk were used per vat of cheese. Mass/balance accounting was done for fat (Mojonnier) and protein (Kjeldahl). Materials and Methods

9. Make Time (min) Trial 1: control 1.3 X 1.6 X 2.0X set-draw 110 97 88 84 draw-mill 154 156 158 164 Total 264 253 245 248

10. Make Conditions Trial 1: control 1.3 X 1.6 X 2.0X draw pH 6.40 6.40 6.40 6.40 mill pH 5.30 5.30 5.30 5.30 rennet (%) 100 80 60 33 cook ( o C) 38 38 38 38 Starter 911 911 911 911 starter added based on cheese weight

11. Milk and Whey Analyses Solids - forced air, 4 h at 100 o C Fat - Mojonnier Protein - macro-Kjeldahl (TN/NCN/NPN) Calcium - atomic absorption Materials and Methods

12. Milk Composition, (%) Trial 1: control 1.3 X 1.6 X 2.0X TS 11.86 d 13.34 c 14.77 b 16.48 a Fat 3.33 d 4.21 c 5.05 b 6.11 a Protein(TN) 3.02 d 3.65 c 4.23 b 4.95 a Casein 2.27 d 2.88 c 3.45 b 4.15 a CN/TP 81.38 d 83.90 c 86.06 b 87.52 a C/F 0.68 0.68 0.68 0.68

13. Whey Composition, (%) Trial 1: control 1.3 X 1.6 X 2.0X TS 6.84 d 6.94 c 7.09 b 7.35 a Fat 0.28 d 0.32 c 0.40 b 0.59 a Protein(TN) 0.93 d 0.99 c 1.04 b 1.10 a NPN 0.27 d 0.29 c 0.31 b 0.33 a

14. Cheese Analyses Moisture - forced air, 24 h at 100 C Fat - Babcock Protein - macro-Kjeldahl Salt - Volhard titration Calcium - atomic absorption Materials and Methods

15. Cheese Composition, (%) Trial 1: control 1.3 X 1.6 X 2.0X Moisture 35.25 34.56 34.42 33.80 Fat 34.47 34.75 34.80 34.81 Protein 24.95 25.11 25.25 25.65 Salt 1.47 1.46 1.49 1.51 pH 5.10 5.12 5.13 5.16

16. pH 4.6 Soluble Nitrogen

17. 12% TCA Soluble Nitrogen

18. Trial 1: control 1.3X 1.6X 2.0X cheese 91.74 92.46 92.43 91.06 whey 7.59 6.57 6.64 7.94 salt whey 1.12 0.86 0.93 0.67 Total 100.44 99.88 100.00 99.67 Results - Fat Recovery, (%)

19. Trial 1: control 1.3X 1.6X 2.0X cheese 72.36 75.84 79.00 82.03 whey 27.27 23.39 20.50 17.95 salt whey 0.54 0.55 0.56 0.43 Total 100.17 99.86 100.07 99.90 Protein Recovery, (%)

20. Protein & Fat Recovery Trial 1: fat recovery in cheese was lower than 93% due to cream separation and recombination no consistent trend in fat recovery protein recovery in the cheese increased and recovery in the whey decreased with increasing concentration factor as expected.

21. Cheese Yield Evaluation Actual Yield Moisture & Salt Adjusted Yield (37 & 1.7%) Modified VanSlyke Formula 1 [(0.93 * % fat) + (% casein - 0.1)] *1.09 Yield = --------------------------------------------------- 1 - (% cheese moisture/100)

22. Barbano Yield Formula A + B + C Yield = ---------------------------------------- 1- ((moisture + salt)/100) A = (0.93) x (% fat in milk) B = (% casein in milk - 0.1) x 1.092 C = other milk solids retained in water phase of the cheese

23. Cheese Yield Efficiency = Moisture & Salt Adjusted Cheese Yield -------------------------------------------------- Theoretical Yield CYE VS - VanSlyke CYE DMB- Barbano Cheese Yield Evaluation

24. Cheese Yield, (%) Trial 1 Control 1.3 X 1.6 X 2.0X Actual 8.81 d 11.12 c 13.33 b 15.87 a Adjusted 9.06 d 11.57 c 13.89 b 16.68 a TY VS 9.13 d 11.58 c 13.92 b 16.82 a TY DMB 9.20 d 11.67 c 14.03 b 16.94 a Y eff. VS 99.24 99.91 99.76 99.14 Y eff.DMB 98.47 99.13 98.99 98.45

25. Acknowledgments Maureen Chapman Laura Landolf Joanna Lynch Pat Wood