• Bioprocessing of brewers’ spent grain for production of Xylanopectinolytic enzymes by Mucor sp.

      Hassan, Shady S.; Tiwari, Brijesh K; Adams, Gwylim A.; Jaiswal, Amit K.; TU Dublin; Science Foundation Ireland; 16/RC/3889 (Elsevier, 2019-12-26)
      The potential of microwave and ultrasound was evaluated for the pretreatment of brewer's spent grain (BSG). Under optimal conditions of microwave and ultrasound pretreatments, reducing sugar yields per 1 g of pretreated BSG were 64.4 ± 7 mg and 39.9 ± 6 mg, respectively. Subsequently, the pretreated BSG was evaluated as a substrate for production of Xylanopectinolytic enzymes using fungi isolated from spoiled fruits. Out of twenty-nine (29) isolates recovered, Mucor sp. (AB1) isolated from Bramley apple (Malus domestica) produced xylanopectinolytic enzymes with higher specific activity, and was selected for further studies. The highest enzyme activity (137 U/g, and 67 U/g BSG, for pectinase and xylanase, respectively) was achieved in a medium that contained 15 g of BSG, at pH 6, temperature of 30 °C, supplemented with 1% xylan or pectin for inducing the production of xylanase or pectinase, respectively. The partially purified xylanopectinolytic enzymes were optimally active at 60 °C and pH 5.
    • Conjugation of soy protein isolate (SPI) with pectin by ultrasound treatment

      Ma, Xiaobin; Hou, Furong; Zhao, Huanhuan; Wang, Danli; Chen, Weijun; Miao, Song; Liu, Donghong; National Natural Science Foundation of China; China Postdoctoral Science Foundation; International Postdoctoral Exchange Fellowship Program; et al. (Elsevier BV, 2020-11)
      The Maillard reaction in the aqueous system with and without ultrasound treatment was used to prepare conjugates between soy protein isolate (SPI) and citrus pectin (CP)/apple pectin (AP). Ultrasound treatment at a power of 450 W and a temperature of 70 °C significantly accelerated the conjugation processes between SPI and pectin samples and led to much greater grafting extents compared to the traditional wet heating. A higher degree of graft of the SPI-CP conjugates was achieved at a shorter ultrasound duration compared to the SPI-AP conjugates, possibly attributed to the larger molecular weight and the more flexible structure of AP. SDS-PAGE analysis confirmed the formation of SPI-pectin conjugates. Analysis of the protein secondary and tertiary structures suggested that the attachment of CP or AP changed the spatial conformation of SPI and led to a looser protein structure. In addition to the grafting process, ultrasound was also observed to play a marked role in unfolding the SPI resulting in more favorable structures for the Maillard reaction. Furthermore, the application of ultrasound to the conjugation process significantly increased the surface hydrophobicity and emulsifying properties of both conjugates, indicating that ultrasound can be a desirable method for protein-polysaccharide conjugation.
    • Effect of ultrasound on physicochemical properties of emulsion stabilized by fish myofibrillar protein and xanthan gum

      Xiong, Yao; Li, Qianru; Miao, Song; Zhang, Yi; Zheng, Baodong; Zhang, Longtao; Fujian Agriculture and Forestry University; Fujian Provincial Foreign Cooperation Project; Fujian Provincial Science and Technology Program of Regional Development Project; National Natural Science Foundation of China; et al. (Elsevier, 2019-04-30)
      To investigate the effects ultrasound (20 kHz, 150–600 W) on physicochemical properties of emulsion stabilized by myofibrillar protein (MP) and xanthan gum (XG), the emulsions were characterized by Fourier transform infrared (FT-IR) spectroscopy, ζ-potential, particle size, rheology, surface tension, and confocal laser scanning microscopy (CLSM). FT-IR spectra confirmed the complexation of MP and XG, and ultrasound did not change the functional groups in the complexes. The emulsion treated at 300 W showed the best stability, with the lowest particle size, the lowest surface tension (26.7 mNm−1) and the largest ζ-potential absolute value (25.4 mV), that were confirmed in the CLSM photos. Ultrasound reduced the apparent viscosity of the MP-XG emulsions, and the changes of particle size were manifested in flow properties. Generally, ultrasound was successfully applied to improve the physical stability of MP-XG emulsion, which could be used as a novel delivery system for functional material.
    • Optimised protein recovery from mackerel whole fish by using sequential acid/alkaline isoelectric solubilization precipitation (ISP) extraction assisted by ultrasound

      Álvarez García, Carlos; Lélu, Pauline; Lynch, Sarah A.; Tiwari, Brijesh K; National Development Plan 2007–2013; MFFRI/07/01 (Elsevier, 2017-10-04)
      The growing fishery industry needs to find new green-processes in order to provide a solution to the huge amount of wastes and by-products that such industrial activity produces. Currently, around a 40% of the total weight of the mackerel is considered a by-product, because just the fillets are used in the food market. ISP method has been revealed as a useful tool for protein recovering, however the yield of this process is traditionally lower than enzymatic methods. In present work, the use of sequential acid/alkaline extraction and alkaline extraction assisted by ultrasound, have been implemented in order to increase the yield of the process. It has been demonstrated that (i) sequential extraction is able to recover practically 100% of total protein, and (ii) applying ultrasound to alkaline extraction is possible to recover more than 95% of total protein from mackerel by-products. Extracted proteins were characterized according to their size, and the amino acid profile of final product was determined.
    • Using ultrasound to measure beef tenderness and fat content

      Allen, Paul; Dwyer, Catherine; Mullen, Anne Maria; Buckin, Vitaly; Smyth, Cormac; Morrissey, Siobhan (Teagasc, 2001-04)
      A new acoustical technique was developed for the quantitative analysis of the texture and composition of meat and meat products. This new approach exploits the fact that the acoustical velocity and attenuation of waves propagated through meat are affected by its mechanical properties, thus allowing characterisation in terms of its composition and eating quality. The method is based on a new high-resolution ultrasonic resonator. This technique is rapid and uses small samples. Procedures for the acoustical analysis of meat were developed and the results were correlated with taste panel and shear force measurements of meat tenderness.