# Sensory Texture and Mastication Physics of Multi-Phase Meat Products
## 4 Results and Discussion
### Food Oral Processing
#### 4.3.2 Influence of Batter-Like Substance (BLS)  
It was observed that the muscle activity was initially on one level (\(\sim\)34-35 \(\upmu\)Vs), decreasing across all sample compositions to about 33 \(\upmu\)Vs in the first quarter of mastication (Figure 5A). From there on, samples with high amounts of BLS phase lead to a further decrease below 31 \(\upmu\)Vs with a slight increase toward the end, while samples composed of structured material show a strong increase to \(>\)37\(\upmu\)Vs in the last quarter. Hence, it is hypothesized that all samples need similar initial work for being broken down. Further processing of the individual particles then strongly depends on their microstructure. Fibrous meat particles require more work for softening and bolus formation as opposed to isotropic gel-like particles [27]. The impact of structured particles is also reflected in an increased maximal EMG value at the late stages of mastication (Figure 5B). Again, all measured samples initially are in a similar region of EMG\({}_{\text{MAX}}\) values (130-150 \(\upmu\)V), increasing until half of the mastication sequence has passed. From there on the increase flattens, however, structured material reaches higher ultimate peak muscle activities (\(>\)200 \(\upmu\)V) than batter-like material (\(\sim\)180 \(\upmu\)V); an effect, that is most likely based on further necessary softening of structured particles to enable the formation of a swallowable bolus. It appearsthat below 40% of structured phase, the characteristics of the batter-like phase dominate, and structured particles are not frequently selected for further softening. This might be due to the already sufficient binding and lubrication by the batter-like phase. The vertical velocity of jaw movement is decreasing over the term of mastication, with a steeper slope toward the last quarter of mastication (Figure 5C,D). Samples with low amount of structured particles seem to induce faster jaw movements. We hypothesize that as the amount of fibrous or anisotropic substance increases, grinding the food between the molars requires higher levels of energy and therefore takes longer. We hypothesize that unlike the structured phase, the batter-like phase is efficiently transferred to a paste-like state and can act as a lubricating and binding phase early in the chewing phase, reducing friction between the structured particles and facilitating the formation of a bolus as described by [PERSON], [PERSON] and [PERSON] [8]. The structured particles must be softened before they are selectable for bolus formation to be eventually swallowed [29]. The time required per bite is initially higher, decreases throughout mastication, and then rises again (Figure 5E). For sample with more structured particles, the effect is shifted toward longer cycle times but follows the same path. [PERSON] [30] described the mastication pathway of dry tough steak similar to the observed one: first, the meat's macrostructure has to be broken down, requiring predominantly cutting action. Then, the sample is transferred to a paste-like state which can form a cohesive bolus by further processing. The duration of the power stroke significantly increased over time and with decreasing amount of batter. In theory, the system is first roughly comminated and cut, with almost no grinding action. The further the system is broken down, the more likely hard particles are entrapped between the teeth, inducing a more extensive power stroke phase to soften and grind the remaining hard particles. The effect on occlusal duration is strongest between 0 and 50% of BLS. Figure 4: Schematic illustration of the food transition from a solid cube to a swallowable bolus during oral processing. Cycle time, maximal muscle activity-, and the integral of muscle activity per bite are shown for fully anisotropic (-) and isotropic samples (- -). (**A–D**) show a hypothesized structure of the matter during oral processing. Dark brown particles and fibrils illustrate structured- and softened meat particles, light brown matter displays meat batter.