THE PENNSYLVANIA STATE COLLEGE THE GRADUATE SCHOOL DEPARTMENT OP DAIRY HUSBANDRY •'ROMANO TYPE" GRATING CHEESE A STUDY OF THE EFFECT OF SOME FACTORS ON THE RATE OF FLAVOR AND BODY AMD TEXTURE DEVELOPMENT A Thesis by JOSEPH FRANCIS MATTICK Submitted in partial fulfillment of the requirements for the degree of DOCTOR OF PHILOSOPHY February 1950 Approved: Head, Depsuytmenif of Dairy Husbandry Professor of Dairy Manufacturing ACKNOWLEDGEMENTS The writer desires to express his appreciation and indebtedness to the following: Dr. C. D. Dahle, for suggesting the problem which was undertaken, for his constant encouragement and many helpful suggestions through construction criticisms throughout the experimental work and prepara tion of this thesis. Dr. D. V. Josephson and Professor A. A. Borland, for placing the facilities of the department at the author’s disposal and making this dissertation possible. Professor F. J. Doan, for his ever willing advice, suggestions, and discussions. Dr. H. 0. Triebold, Dr. A. K. Anderson, and Dr. C. 0. Jensen, Department of Agricultural and Biological Chemistry, and Dr. J. F. Cone and Dr. J. C. Garey, Department of Bacteriology, for their technical advice and suggestions. The graduate students of the Dairy Department, for their inte- r rest, willing discussions of the problems that developed. Kraft Foods, Inc., for the financial assistance given as a research fellowship in the early part of the work. TABLE OF CONTENTS Page INTRODUCTION 1 REVIEW OF LITERATURE 6 A. General Concepts of Catalysis 6 B. General Concepts on Mode of Action 7 C. General Characteristics of a Catalyzed Reaction 8 D. Classification of Biochemical Catalysts 8 E. The Chemical Nature of Enzymes 9 F. General Concepts of Enzyme Action 10 G. Factors Affecting Enzyme Action 11 1. The Effect of Substrates 12 2. The Effect of Temperature 13 3. The Effect of Hydrogen Ion Concentration 14 4. Effect of Activators on Enzyme Activity 15 5. Effect of Inhibitors on Enzyme Activity 16 6. Effect of Time on Enzyme Activity 17 H. Milk Lipase 18 1. Early Concepts of a Milk Lipase 19 2. Methods Used in Studying Milk Lipase 21 3. Factors Affecting Lipase Activity 23 a. Individuality and Stage of Lactation 23 b. Temperature 25 c. Shaking 29 d. Homogenization 30 e. Hydrogen Ion Concentration 34 f. Oxidation 35 g. Proteolysis 37 h. Other Factors 38 I. Pancreatic Lipase 38 J. Rohm and Haas Lipase Preparation 41 OBJECT OF EXPERIMENT 43 EXPERIMENTAL METHODS 45 Preparation 45 Ripening the Milk 46 Setting the Milk 46 Cutting the Curd 47 Cooking the Curd 47 Dipping the Curd 48 Page Salting, Hooping, Pressing, and Dressing the Cheese 4.8 Source and Handling of Cultures 4.8 Sampling 4.9 Fat Determination 49 Total Solids Determination 51 pH Determination 51 Salt Determination 52 Volatile-Soluble and Volatile-Insoluble Fatty Acids 53 Ester Formation 54 Flavor Determinations 56 Body and Texture Determinations 56 DEFINITION OF TERMS 57 EXPERIMENTAL RESULTS 59 I. Natural Milk Lipase Study: Raw Skim— Raw Cream and One Per Cent Streptococcus Lactis 59 Experiment I — 0 Per Cent Cream Homogenized 59 Experiment II - 25 Per Cent Cream Homogenized 61 Experiment III — 50 Per Cent Cream Homogenized 63 Experiment IV - 75 Per Cent Cream Homogenized 65 II. Natural Milk Lipase Study: Raw Skim— Raw Cream and 0.5 Per Cent Streptococcus Lactis and 0.5 Per Cent Lacto bacillus Acidophilus 73 Experiment V - 0 Per Cent Cream Homogenized 73 Experiment VI - 25 Per Cent Cream Homogenized 74 Experiment VII - 50 Per Cent Cream Homogenized 76 Experiment VIII - 75 Per Cent Cream Homogenized 77 Experiment IX - 100 Per Cent Cream Homogenized 79 Experimental Results and Discussion of Experiments I Through IX 87 Flavor in Milk and Whey 87 Membrane Formation 88 Flavors in Cheeses 89 III. Natural Milk Lipase Study: Pasteurized Cream— Raw Skim and One Per Cent Streptococcus Lactis 97 Experiment X - 0 Per Cent Cream Homogenized 97 Experiment XI - 25 Per Cent Cream Homogenized 98 Experiment XII - 50 Per Cent Cream Homogenized 100 Experiment XIII - 75 Per Cent Cream Homogenized 102 Experiment XIV - 100 Per Cent Cream Homogenized 104 Page IV. Natural Milk Lipase Study: Pasteurized Cream— Raw Skim and 0.5 Per Cent Streptococcus Lactis and 0.5 Per Cent Lactobacillus Acidophilus 112 Experiment XV - 0 Per Cent Cream Homogenized 112 Experiment XVI — 25 Per Cent Cream Homogenized 113 Experiment XVII - 50 Per Cent Cream Homogenized 115 Experiment XVIII - 75 Per Cent Cream Homogenized 117 Experiment XIX - 100 Per Cent Cream Homogenized 118 Experimental Results and Discussion of Experiments X Through XIX 127 Flavors in Milk and Whey 127 Membrane Formation 128 Flavors in Cheeses 130 V. Rohm and Haas Lipase Study: Pasteurized Skim— Pasteurized Cream and 1.0 Per Cent Streptococcus Lactis 135 Experiment XX - 0 Per Cent Cream Homogenized 135 Experiment XXI - 25 Per Cent Cream Homogenized 137 Experiment XXII - 50 Per Cent Cream Homogenized 139 Experiment XXIII — 75 Per Cent Cream Homogenized 142 Experiment XXIV — 100 Per Cent Cream Homogenized 144 VI. Rohm and Haas Lipase Study — Pasteurized Skim-— Pasteurized Cream and 0.5 Per Cent Streptococcus Lactis and 0.5 Per Cent Lactobacillus Acidophilus 153 Experiment XXV - 0 Per Cent Cream Homogenized 153 Experiment XXVI - 25 Per Cent Cream Homogenized 155 Experiment XXVII - 50 Per Cent Cream Homogenized 157 Experiment XXVIII— 75 Per Cent Cream Homogenized 159 Experiment XXIX - 100 Per Cent Cream Homogenized 161 Experimental Results and Discussion of Experiments XX Through XXIX 170 Flavors in Milk and Whey 170 Membrane Formation 171 Flavors in Cheeses 172 Re-esterification 174 Homogenization 177 Culture Study 179 VII. Pancreatic Steap3in (Lipase) Study: Pasteurized Cream— Pasteurized Skim and One Per Cent Streptococcus Lactis 180 Experiment XXX - 0 Per Cent Cream Homogenized 180 Experiment XXXI — 25 Per Cent Cream Homogenized 182 Page Experiment XXXII - 50 Per Cent Cream Homogenized 184- Experiment XXXIII — 75 Per Cent Cream Homogenized 186 Experiment XXXIV - 100 Per Cent Cream Homogenized 188 VIII. Pancreatic Steapsin (Lipase) Study: Pasteurized Cream— Pasteurized Skim and Equal Amounts of Streptococcus Lactis and Lactobacillus Acidophilus Culture 196 Experiment XXXV - 0 Per Cent Cream Homogenized 196 Experiment XXXVI - 25 Per Cent Cream Homogenized 19^ Experiment XXXVII - 50 Per Cent Cream Homogenized 199 Experiment XXXVIII - 75 Per Cent Cream Homogenized 201 Experiment XXXIX - 100 Per Cent Cream Homogenized 203 Experimental Results and Discussion of Experiments XXX through XXXIX 211 Flavors in Milk and Whey 211 Membrane Formation 212 Flavors in the Cheeses 212 Homogenization 216 Culture Study 217 SUMMARY 218 CONCLUSIONS 225 BIBLIOGRAPHY 229 APPENDIX INTRODUCTION Prior to World War II, the bulk of the highly flavored condiment type grating cheeses was imported from European countries. It is true that several organizations in the United States were manufacturing domestic products very similar to the imported varieties; however, their production was relatively meager and could obviously be recognized only for its supplementary value. Shortly after the beginning of the war our reserve stocks of the condiment types of cheeses gradually disappeared. This acute shortage and the inability of our domestic industry to adequately meet the na tional demands forced many food processing companies to use milder flavored cheeses with inferior grating properties in their products, or to import cheese from Argentina. This condition manifested itself in the prepared spaghetti dinner components with their pasty, often unclean, cheddar-like flavors. Realizing the secrecy associated with processes and techniques used by the foreign manufacturers — the art of "novelty-type” cheesemaking being handed down orally with a family for centuries — and the close relationship of our domestic-foreign type of grating cheese industry to Italian and family ancestry, it was apparent that application of experi mental evidences would have to be applied to the cheese making process. Attempts at estimating the future status of the foreign cheese market in our country, with evaluations of past records, resulted in 2 many possible problems. If conditions would revert to the pre-war import magnitude, it would be commercially impossible for the domestic industry to compete for that market, without the aid of high protective tariffs because of the marked differences in costs of production, assuming that identical methods of manufacturing were used. Considering our foreign policy with its desire to stabilize foreign economies, it is difficult to realize high protective barriers placed on foreign trade, especially if the products are important sources of revenue for the country or conntries involved. It must also be remembered that the imported cheese products that have reached and will reach our markets have been and will be only the superior grades (from a body and flavor standpoint) which means that we must, of necessity, produce a product consistently comparable to the best that the foreign countries offer. It hasn’t been too many years ago when the old concept prevailed, especially with our naturalized citizens, that foreign products must be made in the country that originally developed them since with our domes tication the individuality of the product was lost. Actually, these products were some of the material linkages that joined their acquired American present with their actual or educated foreign past. The notion that a tradesman’s product and its degree of fineness or perfection was a material personification of himself or his nationality was and is a common impression among our foreign born. These concepts in the past have been the major factors in our meager domestic production since our duplication products were considered inferior by the most important con sumers of the products. 3 The past decade with its war years and various rationings resulted in many changes in food planning. Cheeses, in one form or another, during those years made up a major portion of the meat substitutes be cause of their nutritional value as well as their relatively low cost and adequate availability. One of the most important outgrowths of the food rationing period was the acceptance of the various highly flavored cheeses as condiments. This means that the consumption of these products is no longer, directly or indirectly, controlled by or restricted to the nationalities who have in the past ignored our domestic products in preference to the imported varieties. Italian-type grating cheeses are now just as Americanized as salt or pepper and have rightfully as sumed their accepted position as a seasoning in the American household and food processing organizations. According to Dr. L. S. Palmer's (14-8) chemical definition, "Milk is a microscopic dispersion of fat in an aqueous plasma, containing molecularly dispersed lactose and certain mineral salts, and colloidally dispersed proteins, of which calcium caseinate and lactalburain predo minate, as well as colloidally dispersed calcium phosphate (Ca2H2(P0^)2),f. The various cured and uncured cheeses are the products of degradation or conversion of most of the components of the above mentioned system with such methods and to such degrees that the resultant cheeses main tain the characteristics of their respective types. Each manufacturing process is related to every other process ih many ways and to various degrees; however, each product has its individual characteristics which makes it different from all others. ! A cheese, regardless of type, is composed of many interdependent, complex systems and fundamentally any evaluation of the chemical, physical, or physico-chemical changes that occur in the cheese manu facturing and curing process should engulf the systems as a unit through the study of the effects of the interreaction between systems on all components of the unit. It is our lack of information and techniques that makes such an ideal evaluation impossible at the present time. The concept that a "Romano-type'1 grating cheese can be produced with a short curing period through applications of an experimental process that forces or catalyzes the progress of reactions toward the desirable quality characteristics of the long curing foreign products, has been demonstrated at this institution. Several experiments were made by Dahle, et al. (20) during the past decade in an effort to make a quick curing grating type cheese with encouraging results. The usual curing period for imported and domestic Romano cheese is 10 months to two years. The minimum ripening period required by our legal standards is six months. Since the cost of raw products, manu facturing, equipment, and labor cannot be reduced, the reduction in processing costs must, therefore, occur during the curing process. The curing period of cheese represents a major portion of the costs of manufacturing. Any reduction in the curing time accordingly reduces the manufacturing cost of each unit. The length of the curing period is, therefore, of utmost importance economically to the manufacturer since invested capital could reach appreciable amounts with an exces-