Gelation Characteristics of Tropical Surimi under Water Bath and Ohmic Heating

Gelation characteristics of tropical surimi, namely threadfin bream (TB), bigeye snapper (BS), goatfish (GF) and lizardfish (LF) prepared in the absence and presence of 10 g kg⁻¹ egg white proteins were evaluated using either ohmic (OH) or water bath (WB) heating. LF and GF surimi exhibited higher endogenous proteolytic activity than BS and TB. Ohmic heating markedly minimized proteolysis of LF and GF surimi as evidenced by a reduction of trichloroacetic acid (TCA)-soluble oligopeptide content of gels and more retention of myosin heavy chain (MHC). Ohmic heating increased breaking force and deformation of TB and BS surimi by 1.3 and 1.6 times, respectively, as compared to water bath heating. However, TB surimi gels heated by a higher applied voltage gradient of 16.7 V cm⁻¹ exhibited lower breaking force than those heated at 6.7 V cm⁻¹. Gels heated ohmically contained lower total sulfhydryl concentration, indicating the greater extent of disulfide bond formation as compared to gels heated in a 90 °C water bath. The rapid heating method with shorter heating time could improve water holding capacity and preserve color of tropical surimi gels when compared to water bath heating.Keywords: Water bath heating, Tropical surimi, Ohmic heating, GelationKeywords: Water bath heating, Tropical surimi, Ohmic heating, Gelatio

Dietary creatine supplementation in gilthead seabream (Sparus aurata): comparative proteomics analysis on fish allergens, muscle quality, and liver

The quality of fish flesh depends on the skeletal muscle's energetic state and delaying energy depletion through diets supplementation could contribute to the preservation of muscle's quality traits and modulation of fish allergens. Food allergies represent a serious public health problem worldwide with fish being one of the top eight more allergenic foods. Parvalbumins, have been identified as the main fish allergen. In this study, we attempted to produce a low allergenic farmed fish with improved muscle quality in controlled artificial conditions by supplementing a commercial fish diet with different creatine percentages. The supplementation of fish diets with specific nutrients, aimed at reducing the expression of parvalbumin, can be considered of higher interest and beneficial in terms of food safety and human health. The effects of these supplemented diets on fish growth, physiological stress, fish muscle status, and parvalbumin modulation were investigated. Data from zootechnical parameters were used to evaluate fish growth, food conversion ratios and hepatosomatic index. Physiological stress responses were assessed by measuring cortisol releases and muscle quality analyzed by rigor mortis and pH. Parvalbumin, creatine, and glycogen concentrations in muscle were also determined. Comparative proteomics was used to look into changes in muscle and liver tissues at protein level. Our results suggest that the supplementation of commercial fish diets with creatine does not affect farmed fish productivity parameters, or either muscle quality. Additionally, the effect of higher concentrations of creatine supplementation revealed a minor influence in fish physiological welfare. Differences at the proteome level were detected among fish fed with different diets. Differential muscle proteins expression was identified as tropomyosins, beta enolase, and creatine kinase among others, whether in liver several proteins involved in the immune system, cellular processes, stress, and inflammation response were modulated. Regarding parvalbumin modulation, the tested creatine percentages added to the commercial diet had also no effect in the expression of this protein. The use of proteomics tools showed to be sensitive to infer about changes of the underlying molecular mechanisms regarding fish responses to external stimulus, providing a holistic and unbiased view on fish allergens and muscle quality.Project Allyfish contract MAR 16-02-01-FMP-0014 (PEP 4107IDNAD50308.12) Mar2020info:eu-repo/semantics/publishedVersio

Electric field effects on proteins Novel perspectives on food and potential health implications

Electric fields (EF) technologies have been establishing a solid position in emergent food processing and have seen as serious alternatives to traditional thermal processing. During the last decades, research has been devoted to elucidation of technological and safety issues but also fundamental aspects related with interaction of electric fields (EF) with important macromolecules, such as proteins. Proteins are building blocks for the development of functional networks that can encompass health benefits (i.e. nutritional and bioactive properties) but may be also linked with adverse effects such as neurodegenerative diseases (amyloid fibrils) and immunological responses. The biological function of a protein depends on its tridimensional structure/conformation, and latest research evidences that EF can promote disturbances on protein conformation, change their unfolding mechanisms, aggregation and interaction patterns. This review aims at bringing together these recent findings as well as providing novel perspectives about how EF can shape the behavior of proteins towards the development of innovative foods, aiming at consumers health and wellbeing.This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/ BIO/04469/2019 and UIDB 50006/2020 with funding from FCT/ MCTES through national funds, BioTecNorte operation (NORTE-01- 0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020 - Programa Operacional Regional do Norte. This work was also supported by the projects AlleRiskAssess – PTDC/BAA-AGR/31720/2017 and NORTE-01-0145-FEDER-031720. Zita Avelar acknowledge the Foundation for Science and Technology (FCT) for its fellowship SFRH/BD/146347/2019info:eu-repo/semantics/publishedVersio