Dermot Harrington

Influence of κ-casein genetic variant on rennet gel microstructure, Cheddar cheesemaking properties and casein micelle size

Cheddar cheese was manufactured on three separate occasions over a two week period from milk collected from two mid-lactation, spring-calving, Holstein–Friesian herds (n=11) containing similar casein levels, having phenotype AA or BB for κ-casein genetic variant. κ-Casein variant did not significantly (P>0.05) influence the casein content or gross composition of milk. κ-Cas ein BB milk had significantly smaller average casein micelle diameter and superior rennet coagulation properties than that of the AA milk. Pilot-scale Cheddar cheesemaking studies showed that the κ-casein BB milk resulted in significantly higher fat recoveries into cheese and higher actual and moisture-adjusted cheese yields. Cheese produced from κ-casein BB variant milk had higher concen trations of fat and lower protein levels than that produced from the AA variant. κ-Casein variant had no significant effect on prote olysis or on the acceptability scores awarded to the cheeses.

Composition, microstructure and maturation of semi-hard cheeses from high protein ultrafiltered milk retentates with different levels of denatured whey protein

Abstract Standardized milks, heated at 72–100 °C to denature ~5–63% of the whey protein, were ultrafiltered to yield retentates with protein and fat levels of ~18.5 and 14%, respectively. Retentates were converted into semi-hard cheeses using specialized coagulation and gel-cutting equipment, with scalding and further syneresis being carried out in conventional cheese vats. High heat treatment of milk necessitated an increase in set temperature, a reduction in set pH and higher scalding temperatures in the cheese vat. Cheese from milk heated at 72 °C for 15 s had a mean composition of ~39.8% moisture, 28% protein, 45.1% fat-in-dry matter, 3.5% salt-in-moisture ( S M ) and an ex-brine (1 day) pH of 5.27. Increasing levels of whey protein denaturation (WPD) resulted in cheeses having higher moisture, S M , and whey protein levels, lower ex-brine pH values and lower rates of pH increase during a 182-day ripening period. Cheeses with high levels of WPD also showed poorer curd fusion and lower yield (fracture) values during ripening. Higher levels of denatured whey protein in cheese were associated with a higher degree of primary proteolysis. However, the levels of small peptides (

Effect of altering the daily herbage allowance to cows in mid lactation on the composition, ripening and functionality of low-moisture, part-skim Mozzarella cheese

Milk was collected from three spring-calving herds, on different daily herbage allowances (DHA) of perennial rye-grass (16, 20 or 24 kg dry matter (DM)/cow for a 17 week period. On five occasions, at weekly intervals in the middle of the period, the three different milks were converted into low-moisture part-skim Mozzarella cheese. Increasing the DHA resulted in significant increases in the concentrations of protein in the cheesemilk (P < 0.05) and cheese whey (P < 0.02). The moisture-adjusted cheese yield increased significantly (P < 0.01) on raising the DHA from 16 to 24 kg grass DM/cow. DHA had no significant effects on any of the gross compositional values of the cheese (although moisture and fat-in-DM levels tended to decrease and increase respectively with increasing DHA). The hardness of the uncooked cheese and functionality of cooked cheese (i.e. melt time, flowability, stretch and viscosity) were not significantly influenced by DHA over the 115 d ripening period at 4 degrees C.

Cheesemaking, compositional and functional characteristics of low-moisture part-skim Mozzarella cheese from bovine milks containing κ-casein AA, AB or BB genetic variants

Low-moisture part-skim Mozzarella cheeses were made, at pilot scalen (450 kg), on five occasions at weekly intervals from milks containing κ-caseinn AA, AB or BB genetic variants. Compared with κ-casein A variant milks, then κ-casein B variant milks were associated with higher concentrations of casein ( P P <0·02)n and total protein ( P <0·001), superior curd-forming propertiesn ( P P <0·05).n The moisture-adjusted (to 465 g/kg) cheese yields for the κ-casein AA, AB and BB cheeses were 91·5, 100·6, andn 102·5 kg/1000 kg milk respectively. κ-Casein variant had no significant effect on the proteolysis and ripening of uncooked cheese or on the functionality (meltn time, flowability and stretchability) of the cooked cheese during the coursen of a 90 d ripening period.

Milk protein standardization by ultrafiltration for Cheddar cheese manufacture

Skim milks were concentrated by ultrafiltration. Cream was added to the retentates to give cheesemilks standardized to a casein :fat ratio of ∼ 0.74 with protein levels ranging from 30 to 46 g/l. Pasteurized cheesemilks were renneted on a volume basis (22 ml single strength calf rennet/100 l) and converted to Cheddar cheese in 5001 cheese vats. Set temperatures were reduced from 31 to 28 °C with increasing milk protein level to normalize curd firming rates and prevent curd shattering on cutting the curds. Cheesemaking was otherwise as normal for Cheddar cheese. The proportions of milk fat and protein lost in the cheese whey were not significantly influenced by milk protein level. Moisture-adjusted cheese yields increased with milk protein at a rate similar to that predicted by the Van Slyke cheese yield equation. However, owing to the negative correlation between cheese moisture and milk protein concentration, actual yields increased at a lower rate with respect to milk protein than moisture-adjusted yields. Increasing milk protein levels resulted in significant (P < 0.01-0.001) decreases in the concentrations of moisture, moisture-in-non-fat cheese solids and fat-in-dry matter in the cheese and increases (P < 0.05-0.001) in the levels of protein, salt-in-moisture, Ca and P. While increasing milk protein concentration resulted in significant (P < 0.05-0.01) reductions in the levels of water-soluble N at all stages of the 270 d ripening period, it had little influence on the sensory scores awarded for aroma/flavour at 180 or 270 d.

Are Butter and Cheese Rich in Monounsaturates Beneficial in Hyperlipidaemic Patients

Background Reduction in intake of dairy products has long been recommended to reduce blood lipids. The value of monounsaturated fatty acids is increasingly recognized. Methods We evaluated the effects of a monounsaturate-rich butter and cheese (B) produced by modifying the bovine diet on blood lipid levels of patients with type lla hyperlipidaemia. We compared their effects with those of normal butter and cheese (A) and polyunsaturate-rich spread and cheese (C). Using a double cross-over design, we studied 30 patients of mean age 56.4 years (23 men, one woman excluded) over 6-week periods. Results Approximately 35.5 g/day butter/cheese were consumed; no changes in serum total cholesterol, triglycerides, low-density lipoprotein, lipoprotein (a) or cholesterol: High-density lipoprotein (HDL) ratio were observed. HDL levels were higher in B (1.31 mmol/l) than in C (1.22 mmol/l; P < 0.05) and similar to those in A (1.28 mmol/l). HDL2 levels were higher in patients fed diet A (0.23 mmol/l) than they were in those fed diet C (0.19 mmol/l; P < 0.05) and similar to those in patients fed diet B (0.20 mmol/l). Serum HDL3 was significantly higher in patients fed diet B (1.11 mmol/l) than in those fed diet C (1.03 mmol/l; P < 0.05) but similar to that in patients fed diet A (1.06 mmol/l). Conclusions Moderate intake of modified dairy products may be of value and deserves further evaluation.