Instron texture profile of buffalo milk cheddar cheese as influenced by composition and ripening changes

Buffalo milk Cheddar cheese samples of different ages were analysed for compositional attributes (CA), ripening indices (RI) and Instron Textural Profile (ITP). All samples were compositionally alike, except for pH and salt-in-moisture (SM) contents. RI showed significant variations. CA and RI showed highly significant correlations within themselves and with each other, except for moisture with pH, SM with moisture, MNFS, Fat and FDM and Fat with MNFS. The ITPs of cheeses showed significant variations and had highly significant intercorrelations indicating their interdependence. CA (except moisture and MNFS) and RI showed a highly significant correlationship with ITPs. Moisture content showed a highly significant correlationship with all ITPs, except cohesiveness and springiness, where it was significant. MNFS content showed significant correlations only with hardness and brittleness. Stepwise regression analysis revealed that MI was the most predominant factor influencing cheese texture, followed by pH, SM, FDM and TVFA. Knowing Ca and RI, the textural properties of cheeses can be forecast through mathematical equations. Similarly the age of cheese can also be predicted if RI and/or textural properties are known.     

An Investigation of Milk Powders Produced by a Laboratory-Scale Spray Dryer

A mini spray dryer has been used to investigate morphological changes that occur to milk particles during the spray drying process. We have found that the mini spray dryer is ideal for such investigations, because phenomena such as skin and vacuole formation in particles can be analyzed without the added complication of particle agglomeration, which only occurs in much larger spray dryers where particle number concentrations are higher. We have confirmed observations made by various researchers that the bulk density of spray-dried milk powder is greatly affected by the drying temperature, due to the strong influence of the latter on the porosity of the particles. In addition, we have attempted to explain observations made by various workers that fat accumulates preferentially at the surface of a particle during drying by postulating that fluid fat is transported towards the surface, via a network of cracks and pores, by the development of a vacuole overpressure which is also responsible for the inflation of the particle. Finally, we have shown that milk powders can be spray dried a second time, by reconstitution with water, with no change to the thermodynamic characteristics of the resultant powder. Thus, milk concentrates for spray drying research can be prepared from already-spray-dried milk powders rather than using the more arduous evaporation method to concentrate unprocessed milk.     

Final Drying of Whole Milk Powder in Vibrated-Fluidized Beds

Vibro-fluidized beds are widely used in drying sticky powders and agglomerated materials as milk powder. Using a vibro-fluidized laboratory scale dryer, this work is aiming at analyzing preliminarily the effect of its operational variables on the drying kinetics and characteristics of whole milk powder. The full-factorial design technique with three replications at the central point has been employed to generate data and correlations to quantify the effect of inlet air temperature, air flow rate, and vibration bed amplitude on the drying curves and the milk powder properties related to its faster reconstitution in water (as tapped density, Hausner cohesion ratio, agglomerate size distribution, and internal pore concentration). Results obtained are analyzed and discussed to identify the adequate operation condition for final drying whole milk powder in vibro-fluidized beds, assuring a high product quality.     

牛奶纤维理化性能及其开发应用探讨

文章介绍了牛奶纤维的理化性能,利用纤维强伸度测试仪对牛奶纤维的机械性能进行了测试,利用差示扫描量热器和热重分析仪对牛奶纤维的热学性能进行了分析研究。分析了牛奶纤维的化学性能、染色性能及保健护肤、天然抑菌等特殊功能,探讨了牛奶纤维的产品开发和应用。     

The occurrence of Staphylococcus aureus in fermented milk products (Fura and Manshanu) in Nigeria

Ninety-three samples of fermented milk cereal (Fura) and 79 of local butter (Manshanu) were collected from four different markets around Zaria. For Fura the mean content of Staphylococci for each of the four markets ranged from 4.5 × 10³ to 4.3 × 10⁴ cfu/ml and the mean aerobic mesophilic plate count from 5.6 × 10⁵ to 2.7 × 10⁶ cfu/ml. For Manshanu the mean staphylococcal count and aerobic mesophilic plate count ranged from 3.4 × 10² to 2.2 × 10³ cfu/ml and 6.7 × 10⁴ to 1.1 × 10⁶ cfu/ml respectively. Significant differences were seen between the different markets.     

Mg2+ Selectively Isolates Gellan Gum from Dairy Products

Gellan gum was precipitated from the papain digest of dairy products by 5% MgSO₄. The precipitate was collected by centrifugation and washed with 2.5% MgSO₄ until the washings were negative to the phenol H_aSO₄ test. It was dispersed with hot 50% H₂SO₄ and the amount in the dispersion determined by the H₂SO₄-thiourea-cyste-ine-HCl reagent. Recovery from chocolate milk, yogurt, evaporated milk, ice cream, cream cheese, process cheese spread, flan and blue cheese (no oil) dressing ranged from 76–95%. Prior removal of fat and starch was unnecessary. Carrageenan, xanthan gum, alginate, pectin and other hydrocolloids did not interfere.     

Vitamin D Stability in Milk

A method was developed to determine vitamin D₃ in milk. It includes saponification, solid phase extraction and HPLC. Recovery of added vitamin D₃ was 93%. Vitamin D₃ concentrations in commercial milks were variable. Stability studies showed that on exposure to light, there was a slight loss of vitamin D₃ from fortified milk. Air exposure did not affect stability in milk. Upon standing there was some stratification of the vitamin in milk containers with slightly more vitamin D₃ in the top layer of milk than at the bottom.     

利用乳蛋白改善肉糜制品质量

乳蛋白是肉糜制品的优质乳化剂,它能与水和脂肪界面充分结合,形成较为稳定的水—蛋白质—脂肪系统,合理使用,可赋予成品良好的风味和口感及优良的物理性能.同时使用乳蛋白还可以尽量利用生产中的边角余料、低档肉,提高肉的利用率,降低生产成本.     

Listeria monocytogenes: Its importance in the dairy industry

Recent outbreaks of listeriosis associated with consumption of milk products contaminated with Listeria monocytogenes have focused attention on the importance of food-borne transmission of this disease. This review outlines current knowledge of the incidence of L monocytogenes in raw milk and its incidence in, and ability to survive, the manufacturing process for other dairy products—notably soft cheeses. Discrepancies in results obtained by researchers concerning growth of the organism at refrigeration temperatures and the bacterium's ability to survive pasteurisation are discussed.     

Magnetic Treatment of Milk and Surface Treatment of Plate Heat Exchangers: Effects on Milk Fouling

After milk property effect was eliminated, relative fouling rates of electropolished stainless steel, 304 stainless steel, titanium, polysiloxane and Teflon were 0.99,1.00,1.01,1.14, and 1.20, respectively. No significant reduction of cleaning time was found on the Teflon-coated plate although Teflon had significantly larger contact angles in both surface-water-air and surface-water-octane than did stainless steel. Magnetic field treatment of milk and calcium phosphatase solution did not significantly affect fouling rates or type of calcium phosphate crystals in deposits.