Browsing by Subject "high-moisture extrusion"

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  • Liu, Yu (Helsingin yliopisto, 2021)
    A growing population is suffering from protein insufficiency and seas of over-fishing. On the other hand, an abundant amount of low-value or underutilized fish species remains unexploited for human consumption mainly due to low consumer preferences. For this reason, new solutions are needed to utilize these fish better. This study was carried out in two phases. In phase I, extrudates from five underutilized fish species and pea protein isolate (PPI) were produced by using a high-moisture extrusion process (HMEP). The aim was to successfully produce extrudates and study their sensory and texture properties by generic descriptive analysis (GDA), instrumental color measurements, and instrumental tensile strength measurements. In phase II, PPI was partially replaced in the recipe by two cereal fractions. The experiment was generated by simplex-centroid mixture design to study the effects of PPI and two cereal fractions on the texture of extrudates. The results of phase I showed that the extrudates were successfully produced. Extrudates from Baltic herring were one extreme with intense flavor and odor, such as seaweed, and the highest fracturability. Smelt extrudates were another extreme with intense flavor, odor, and greyness. For further studies, a combination of the present analytical sensory profiling data and the hedonic response of consumers will be needed for the product development. In phase II, the extrudates produced from a low amount of PPI with a high amount of cereal fractions were doughy and too soft. Other ingredients should be considered in further studies to replace PPI.
  • Immonen, Mika; Chandrakusuma, Angga; Sibakov, Juhani; Poikelispaa, Minna; Sontag-Strohm, Tuula (2021)
    Grain protein fractions have great potential as ingredients that contain high amounts of valuable nutritional components. The aim of this study was to study the rheological behavior of destarched oat and pea proteins and their blends in extrusion-like conditions with a closed cavity rheometer. Additionally, the possibility of producing fibrous structures with high-moisture extrusion from a blend of destarched oat and pea protein was investigated. In the temperature sweep measurement (60-160 degrees C) of the destarched oat protein concentrate and pea protein isolate blend, three denaturation and polymerization sections were observed. In addition, polymerization as a function of time was recorded in the time sweep measurements. The melting temperature of grain proteins was an important factor when producing texturized structures with a high-moisture extrusion. The formation of fibrillar structures was investigated with high-moisture extrusion from the destarched oat and pea protein blend at temperatures ranging from 140 to 170 degrees C. The protein-protein interactions were significantly influenced in the extruded samples. This was due to a decrease in the amount of extractable protein in selective buffers. In particular, there was a decrease in non-covalent and covalent bonds due to the formation of insoluble protein complexes.
  • Rekola, Silja-Maria (Helsingin yliopisto, 2021)
    The increasing awareness of consumers on sustainability issues associated to meat consumption has led to the increased demand for plant-based meat alternatives. There has been little information on the effects of dietary fibres (DF) in the formulation of meat analogues, but they could be potential raw materials due to their high nutritional value and diverse functional properties. Therefore, the aims of the study were to understand the role of processing parameters on protein-DF interaction and structure formation during high moisture extrusion (HME). Depending on the type of DF, protein, and extrusion conditions, influences on the structure can be either advantageous or cause limitations. HME was used to produce meat analogues from pea protein isolate (PI) and concentrate (PC), and 18 different protein-bran formulations were prepared with inclusion of oat bran (OB), wheat bran (WB) or a combination of both in concentrations of 5, 10, and 15%. The proximate composition of raw materials and extrudates was determined. In order to understand the effect of DFs on the meat analogues, the produced extrudates were evaluated in terms of colour, textural properties, microstructure, and protein-protein interactions. OB and WB had an influence on the formulations by decreasing the protein content while increasing the DF and starch content which could be related to changes occurring during processing. Increased tensile strength and cutting strength were observed in one direction resembling meat fibres. However, meat analogues with brans exhibited weaker structures by increasing softness. The findings on protein solubility indicated both non-covalent and disulphide bonds having a role in the structural stabilisation and fibrillation of meat analogues. However, the inclusion of brans did not have a significant effect on protein-protein interactions. In conclusion, brans have potential as raw materials in meat analogues for texture improvement. Further studies on consumer acceptance and improving process optimisation are suggested.