Raman spectroscopy and NIR hyperspectral imaging for in-line estimation of fatty acid features in salmon fillets

Raman spectroscopy was compared with near infrared (NIR) hyperspectral imaging for determination of fat composition (%EPA + DHA) in salmon fillets at short exposure times. Fillets were measured in movement for both methods. Salmon were acquired from several different farming locations in Norway with different feeding regimes, representing a realistic variation of salmon in the market. For Raman, we investigated three manual scanning strategies; i) line scan of loin, ii) line scan of belly and iii) sinusoidal scan of belly at exposure times of 2s and 4s. NIR images were acquired while the fillets moved on a conveyor belt at 40 cm/s, which corresponds to an acquisition time of 1s for a 40 cm long fillet. For NIR images, three different regions of interest (ROI) were investigated including the i) whole fillet, ii) belly segment, and iii) loin segment. For both Raman and NIR measurements, we investigated an untrimmed and trimmed version of the fillets, both relevant for industrial in-line evaluation. For the trimmed fillets, a fat rich deposition layer in the belly was removed. The %EPA + DHA models were validated by cross validation (N = 51) and using an independent test set (N = 20) which was acquired in a different season. Both Raman and NIR showed promising results and high performances in the cross validation, with R2CV = 0.96 for Raman at 2s exposure and R2CV = 0.97 for NIR. High performances were obtained also for the test set, but while Raman had low and stable biases for the test set, the biases were high and varied for the NIR measurements. Analysis of variance on the squared test set residuals showed that performance for Raman measurements were significantly higher than NIR at 1% significance level (p = 0.000013) when slope-and-bias errors were not corrected, but not significant when residuals were slope-and-bias corrected (p = 0.28). This indicated that NIR was more sensitive to matrix effects. For Raman, signal-to-noise ratio was the main limitation and there were indications that Raman was close to a critical sample exposure time at the 2s signal accumulation.publishedVersio

Raman spektroskopi for målinger av matkvalitet i prosesslinjen

A major challenge in the food industry is to effectively handle massive streams of food raw materials and products of different origin and quality. In-line sensor systems for food analysis can potentially measure and collect critical quality and safety parameters throughout the processes. This information can be used for sorting, product differentiation, process optimisation and product control. One emerging technology that shows great promise for future in-line food sensor systems is Raman spectroscopy. The overall goal of this thesis was to elucidate the feasibility of Raman spectroscopy as a tool for detailed quality evaluation of heterogeneous food raw materials, under in-line industrial conditions. To this end, two main application areas were chosen, including A1) in-line measurements of fatty acid features in salmon fillets and A2) in-line characterization of a poultry rest raw material stream. A central element in both application areas was the use of a Wide Area Illumination (WAI) Raman probe to obtain representative measurements of the heterogeneous raw materials and to tackle variations in working distance. Variations in working distance may easily happen in an industrial process line with samples of varying thicknesses and streams of varying production volumes. The limited measurement volume of the WAI probe was increased by scanning over the sample surface. We showed that this strategy was successful with respect to obtaining representative measurements. This was demonstrated through obtaining good performances for EPA+DHA estimation in salmon fillets of varying thickness (± 1 cm) and through characterization (fat, protein, bone and collagen) of poultry rest raw material with larger variations in working distances (± 3 cm). For the latter study, the method was also tested in-line at a real hydrolysis facility with promising results. For the study on salmon fillets, the varying fat deposition across the fillets was shown to have implication for choice of scanning strategy at shorter exposure times due to impact on signal-to-noise ratio (SNR). This illustrates the importance of considering the heterogeneity of the food product in a given application, and of optimizing measurement strategies accordingly. Another main objective was to elucidate the ability of Raman measurements to tackle short exposure times. This is of particular importance for measurements of single samples at a conveyor belt, where exposure time is strictly limited. This was investigated in paper I and II, where we measured single salmon and poultry samples at exposure times down to 1 s. While exposure times around 2-1 s in these cases did give acceptable performances, it was evident that these low exposure times reduced SNR and performance and that SNR was a critical parameter. This indicates that at shorter exposure times, the surface scanning with theWAI Raman probe might be less robust with respect to tackling samples of varying sample sizes or lower analyte concentrations. Therefore, for such single samples, WAI Raman spectroscopy is currently better suited for fast at-line or on-line measurements. However, such measurements could also have high value for the industry, as it represents a frequent quality feedback, which is currently lacking. Overall, it was found that further efforts on calibration development, SNR optimization and practical measurement setup are needed to unlock the full potential for in-line measurements in the two application areas. Still, this thesis has shown that it is feasible to use a WAI Raman probe for detailed characterization of very heterogeneous streams of raw material, at industrially relevant speeds and in presence of moderate variations in working distance and probe tilt. It was shown that WAI Raman spectroscopy is promising, both for measurements of continuous raw material streams and single food products on a conveyor belt. This introduces many new application opportunities for Raman spectroscopy within quality documentation, sorting, process analysis and real-time process control in the food industry.En stor utfordring for matindustrien er å håndtere store strømmer av råvarer og produkter av forskjellig opprinnelse og kvalitet på en effektiv måte. Sensorsystemer som kan brukes direkte på prosesslinjene, såkalt ”in-line”, kan potensielt måle og samle kritisk informasjon om matkvalitet og mattrygghet. Resultatet er verktøy for sortering, produktdifferensiering, prosessoptimering og produktkontroll. Raman spektroskopi er en lovende teknologi under utvikling med stort potensiale som sensorsystem i matindustrien. Målet med dette doktorgradsprosjektet var å undersøke mulighetene for å bruke Raman-spektroskopi som et verktøy for kvalitetsmålinger av heterogene matråvarer direkte i prosesslinjen. For å nå dette målet ble to bruksområder valgt, inkludert A1) in-line målinger av fettsyreprofil i laksefileter og A2) in-line karakterisering av råvarestrømmer fra fjærfe-produksjon. Et sentralt tema for begge bruksområdene var bruken av en Raman-probe med bredt belysningsområde (WAI) for å oppnå representative målinger av heterogene råvarer og for å takle variasjoner i arbeidsavstand. Variasjoner i arbeidsavstand kan fort oppstå i en industriell prosesslinje med prøver av varierende tykkelse og for stømmer med varierende produksjonsvolum. Fokusvolumet til WAI-proben ble økt ved å skanne over prøveoverflaten. Vi viste at denne strategien fungerte godt for å oppnå representative målinger. Dette ble demonstrert ved å oppnå lave prediksjonsfeil for EPA + DHA-estimering i laksefileter med varierende tykkelse (± 1 cm) og for karakterisering (fett, protein, bein og kollagen) av kyllingråstoff med større variasjoner i arbeidsavstand (± 3 cm). For sistnevnte studie ble metoden også testet in-line på et industrielt hydrolyseanlegg, med lovende resultater. For studien på laksefileter ble det vist at det varierende fettinnholdet på filletoverflaten hadde betydning for valg av skannestrategi ved kortere eksponeringstider, grunnet effekten på signal-støy-forholdet. Dette illustrerer hvor viktig det er å gjøre nøye vurderinger av heterogeniteten til et gitt matprodukt, og å optimalisere målestrategien deretter. Et annet hovedmål var å undersøke hvordan Raman-målingene håndterte kortere eksponeringstider. Dette er av spesiell betydning for målinger av enkeltprøver på et transportbelte, der eksponeringstiden er sterkt begrenset. Dette ble undersøkt i artikkel I og II, der vi målte enkeltprøver av laks og fjærfe-restråstoff ved eksponeringstider ned til 1 s. Selv om eksponeringstider rundt 2-1 s i disse tilfellene ga akseptable prediksjonsfeil, var det tydelig at disse lave eksponeringstidene reduserte signal-støy-forholdet og dermed prediksjons-prestasjonen. Signalstøy- forholdet er altså en kritisk faktor, og dette indikerer at skanning med WAI Raman-proben kan være mindre robust når det gjelder å håndtere prøver med varierende prøvestørrelser eller lavere analytt-konsentrasjoner, ved slike korte eksponeringstider. Derfor er Raman-målingene foreløpig bedre egnet for hurtige målinger ved siden av produksjonslinjen (”at-line” eller ”on-line”), for enkeltprøver. Slike målinger kan også ha høy verdi for industrien, da det representerer et system som gir hyppig tilbakemelding på kvalitet, noe som det for øyeblikket ikke finnes løsninger for. En videre innsats innen kalibreringsutvikling, SNR-optimering og utvikling av praktisk måleoppsett er nødvendig for å realisere det fulle potensialet for in-line Raman-målinger i de to applikasjonsområdene. Likevel har dette doktorgradsprosjektet vist at det er mulig å bruke en Raman probe med bredt belysningsområde til detaljert karakterisering av av svært heterogene strømmer med råvaremateriale, ved industrielt relevante eksponeringstider og med moderat variasjon i arbeidsavstand. Det ble vist at WAI Raman spektroskopi er lovende både for målinger på kontinuerlige råvarestrømmer og enkeltprøver på et transportbelte. Dette muliggjør en rekke nye applikasjoner for WAI Raman spektroskopi innen kvalitetsdokumentasjon, sortering, prosessanalyse og sanntids prosesskontroll i matindustrien

Diet: Microbiota Interaction in the Gut-Focus on Amino Acid Metabolism

This study aims to measure the impact of protein and amino acid fermentation on the composition and metabolic output of gut microbiota. Although dissimilatory pathways have been described for most amino acids, microbial degradation routes within the gut microbiota are relatively unexplored. The objectives were (1) to characterize amino acid breakdown by the colonic microbiota, (2) to determine the fermentation products formed from individual amino acids/protein (3) to examine how amino acid metabolism is impacted by the presence of a fermentable fiber (prebiotic inulin) and finally (4) to evaluate with an in vivo model (trout fish) diet:microbe interactions and the development of gut microbiota during fish farming. Interactions between the healthy human intestinal microbiota of the distal colon and different combinations of nutrients were simulated using in vitro pH-controlled anaerobic batch cultures of human faeces. Combining high-throughput sequencing of 16S rRNA amplicons, with high-throughput 1H NMR, changes in faecal microbiota composition and metabolic output were measured. During exogenous substrate microbial fermentation (e.g. beef, Trp or fish feed) in the large bowel bioactive compounds (harmful or beneficial) are produced. Many factors affect the gut-microbial metabolism including pH, type and quantity of growth substrate (e.g. protein/carbohydrate) and make up of the gut microbiota. Considerable interindividual variation was observed in response to different digested substrates but over all, the beneficial impact of prebiotic fiber fermentation on production of bioactive compounds from amino acids/proteins was confirmed in this study. In trout, although our dietary intervention with essential oils had little impact on the gut microbiota, the study showed for the first time a dramatic shift in the composition and diversity of the gut microbiota in juvenile, compared to adult fish. Thse observations may have relevance in designing dietary strategies to reduce chronic diseases like colon cancer and heard disease and for fish farming respectively

Manutenção da certificação Marine Stewardship Council (MSC) em empresa de processamento de pescado e classificação qualitativa da supply chain

Dissertação de mestrado em Tecnologia e Ciência AlimentarA dissertação incide sobre a manutenção da certificação Marine Stewardship Council (MSC) aliada a uma revisão das metodologias de controlo de qualidade em pescado congelado na receção das matérias primas, quer para utilização na unidade produtiva quer para comercialização direta (trading). A Brasmar está certificada pela Marine Stewardship Council (MSC) desde 2016, sendo uma organização que promove a pesca sustentável, trabalhando com toda a cadeia de produção e consumo. No entanto, o seu maior contributo é dado quando o trabalho é desenvolvido junto das entidades piscatórias e operadores que atuam nas primeiras etapas da cadeia de distribuição e comercialização do pescado. O controlo de qualidade dos produtos é uma ferramenta benéfica e importante para manter a qualidade e exigência dos produtos e alimentos do setor agroalimentar. Devido à exigência e diversidade dos mercados, verifica-se a necessidade de desenvolver uma revisão aos critérios de análise sensorial com base nas características sensorials, que esteja estruturado da seguinte forma: parâmetros gerais (transversais às caraterísticas do pescado) e parâmetros específicos por produto e espécie. O desenvolvimento destes parâmetros teve por base metodologias utilizadas pela indústria do pescado e validadas pela comunidade científica que foram adaptadas à atividade desenvolvida pela empresa de modo a tornar os resultados do controlo mais coerentes e fidedignos. A classificação dada aos parâmetros deste controlo remeterá para uma avaliação final do lote de produto analisado. A empresa gere-se por um sistema de gestão de qualidade que terá como base os resultados obtidos a partir da classificação dada ao lote de produto, que por sua vez irá alimentar a avaliação de fornecedores resultando numa classificação qualitativa da supply chain atendendo apenas à avaliação pelos critérios de análise sensorial. Deste modo é promovida a comunicação entre as partes interessadas e a melhoria continua de toda a organização.The focus of this dissertation is on maintaining the Marine Stewardship Council (MSC) certification together with a review of the quality control methodologies in frozen fish, in the reception of raw materials, either for use in the production unit or for direct sale (trading). Brasmar has been certified by the Marine Stewardship Council (MSC) since 2016, being an organization that promotes sustainable fishing, working with the entire production and consumption chain. However, its greatest contribution is given when the work is developed with the fishing entities and operators that work in the first stages of the fish distribution chain and commercialization The quality control of products is a beneficial and important tool to maintain the quality and demand of products and food in the agrifood sector. Due to the demand and diversity of the markets, there is a need to develop a review of the sensory analysis criteria based on the organoleptic characteristics that is structured as follows: general parameters (transversal to the characteristics of the seaood) and specific parameters by product and species. The development of these parameters was based on methodologies used by the fish industry and validated by the scientific community, which were adapted to the activity developed by the company in order to make the control results more coherent and reliable. The classification given to the parameters of this control will refer to a final evaluation of the analyzed product batch. The company is managed by a quality management system that will be based on the results obtained from the classification given for the product batch, which in turn will feed the evaluation of suppliers resulting in a qualitative classification of the supply chain serving only the evaluation by sensory analysis. In this way, communication between stakeholders is promoted, together with the continuous improvement of the entire organization

Progress on Nutrient Composition, Meat Standardization and Grading, Processing and Safety in Different Types of Meat Sources

The alleged responsibility of meats and processed meat products for some of our population’s major health issues has created an opportunity for the promotion of meat analogs. This emerging competition forces the need for changes in livestock production systems for improving nutritive value and obtaining healthier and safer meat products. The morbidity and mortality attributed to Salmonella and other pathogens remain a public health issue. Hence, there is an urgent need for developing intervention technologies to control such pathogens. Beef is packaged with an array of healthy nutrients and is the highest valued livestock product. However, staples (e.g., pork, poultry) and some co-products can also be nutrient dense and/or provide a unique sensory experience with advantageous technological quality. Carcass yield is a major determinant of livestock value. Hence, objective technologies are strongly needed to effectively segregate the heterogeneous supply of carcasses into homogeneous groups in yield of cuts. Not all meats are created equal, and differences in their intrinsic characteristics may be expected when they are produced in different regions and under diverse production schemes. Nevertheless, reports aiming to characterize meats originated from different zones (e.g., tropical latitudes) are scarce. This Special Issue of Foods, “Progress on Nutrient Composition, Meat Standardization, Grading, Processing, and Safety for Different Types of Meat Sources”, comprising fourteen peer-reviewed papers, is now being released as a book that will serve as an invaluable reference in addressing the current dearth of knowledge regarding the aforementioned topics, and is also envisaged to serve in updating food scientists and stakeholders of the meat value chain globally