Molecular gastronomy is a new scientific field concerned with domestic and restaurant cooking, perception of food, and other factors relevant for cooking and meals. Most available gastronomic knowledge is based on experience and handed-down procedures from cookbooks and recipes. This inductive way of gathering knowledge can lead to false conclusions as to which parameters really affect the result of e.g. a cooking process, and molecular gastronomic studies can thus provide a basis for cooking based on scientific knowledge.
The present thesis investigates a specific cooking method, low-temperature long-time sous-vide-cooking of meat. This method is increasingly used, especially in high-end restaurants, where it receives much praise from leading chefs worldwide. Sous-vide-cooking uses vacuum-packaging of the meat and preparation in thermostated water-baths at temperatures between 54°C and 65°C for periods of time ranging from 20 minutes up to as much as 3 days. Thus, this way of cooking opens up an entirely new space of time-temperature combinations that can be utilised by the chef. The scientific literature in the area is scarce, and before the work presented here, no studies have seen low-temperature long-time heat treatment of meat from a gastronomic viewpoint.
The effect of cooking time and cooking temperature on the sensory properties of beef eye of round (semitendinosus) was investigated by a sensory descriptive study. The results showed that both cooking time (3, 6, 9, and 12 hours) and cooking temperature (56°C, 58°C, and 60°C) affected the sensory properties. All the studied combinations of time and temperature gave a unique set of sensory properties, which means that changes in cooking time cannot be compensated for by changes in cooking temperature and vice versa.
Furthermore, it was shown that the sensory descriptors could be divided in three groups according to their time-temperature behaviour. Two of the groups showed the same overall behaviour with time and temperature working in the same direction. However, the dependence on time and temperature differed between the groups. The third group showed a different behaviour; in this group time and temperature worked in different directions. Thus, the results showed three dominant behaviours in sensory properties.
Two sensory properties, tenderness and juiciness, are very important in cooked meat according to both consumers and chefs. Tenderness was shown be iiidecreased by increased cooking temperature and increased by increased cooking time. Juiciness was also shown to be decreased by increased cooking temperature but decreased by increased cooking time. As a result, tenderness and juiciness cannot be maximised simultaneously by low-temperature long-time cooking due to the different influence of time and temperature on these properties. Hence, the chef has to balance tenderness and juiciness in a way that suits the dish.
The work in the present thesis is a starting point for further modelling of the cooking process for meat. The next step could be an attempt to predict sensory properties based on temperature profiles obtained during cooking. There are still very few scientific studies in the molecular gastronomy field, but hopefully the future brings more studies in this area leading to even more delicious foods in the future.