You can’t tell them apart at first glance, so what’s the difference? dTest tested a total of 25 samples of fresh and long-life milk for fat and protein content. Sensory evaluation, microbiological safety and packaging declarations were also carried out.
Fifteen fresh and 10 long-life semi-skimmed milks, both Czech and Slovak and one Croatian, were sent to the laboratory. In addition to conventional and private label milks, two labelled “organic” were also represented.
“We started the test by measuring fatness. The legislation insists on a fatness of at least 1.50% with accuracy to hundredths. Half of the milks, however, fell a few hundredths short of the prescribed minimum, and we found a value of 1.50% or more in only 12 out of 25 samples,” says Hana Hoffmannová, editor-in-chief of dTest magazine. The laboratory found the lowest fat content in the Slovak product Tami Tatranské Bio mlé.
In milk, protein is just as important as the amount of fat. All samples met the requirements of the regulation, which stipulates the protein content of milk. Tesco UHT semi-skimmed long-life milk boasted the highest protein concentration.
The judges next evaluated appearance, consistency, taste and aroma. They focused on any signs of ungentle treatment, milky deposits on the bottom and defects in consistency. They also looked for undesirable bitter, salty, astringent and cheesy flavours. All the milks passed the strict requirements. The best fresh milks made a better impression than the best long-life milks – the fresh milks left with an average of 84%, the long-life with 83%.“We had hoped to reveal the most significant differences between fresh and long-life milk from the microbiological analysis. It should be specified that even milk offered as fresh undergoes a heat treatment that destroys the vast majority of living microorganisms in it. In the case of long-life milk, however, an even more thorough treatment is applied,” says Hana Hoffmann, adding: “With milked raw milk, the total number of microbes in a millilitre can range up to around 50 000 organisms. In the samples of long-life milk we tested, we found a net zero in all cases. Fresh milk consistently showed a value of less than 10.
Milk is most commonly associated with calcium content, so further chemical analysis focused on calcium. The milks tested did not deviate much from the expected theoretical calcium concentration. The lowest level of dTest was found in Madeta brand long-life milk, while Milkin fresh milk was the richest in calcium.
The focus of the test belonged to the data on the packaging. “For milk labelled as ‘organic’ we looked for certificates and labels of origin. However, we also looked for the origin of the milk in other products. This information is not yet mandatory, but we found it on a number of packages. Most often they took the form of the Czech Food logo, which guarantees 100% Czech ingredients in single-ingredient foods,” explains Hana Hoffmannová.
Throughout the test, fresh and long-life milk managed to keep up. The most significant difference was the aforementioned microbiological purity. The results of the sensory evaluation confirmed that fresh milk tastes slightly better. The long-life milks were more likely to have problems with consistency and palatability. In other chemical analyses, both groups performed essentially the same with respect to measurement uncertainty.