The impact of processing conditions on enzymatic protein hydrolysis performance from sardine (Sardina pilchardus) by-products using Alcalase 2.4L, and the influence on final spray dried hydrolysate powder properties

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dc.contributor.advisorGoosen, Neill Jurgensen_ZA
dc.contributor.authorChiodza, Godknows Kudzaien_ZA
dc.contributor.otherStellenbosch University. Faculty of Engineering. Dept. of Chemical Engineering. Process Engineering.en_ZA
dc.date.accessioned2023-11-29T08:15:07Zen_ZA
dc.date.accessioned2024-01-08T21:01:25Zen_ZA
dc.date.available2023-11-29T08:15:07Zen_ZA
dc.date.available2024-01-08T21:01:25Zen_ZA
dc.date.issued2023-12en_ZA
dc.descriptionThesis (PhD)--Stellenbosch University, 2023.en_ZA
dc.description.abstractENGLISH ABSTRACT: Sardine processing by-products are a valuable resource that is currently underutilised. Currently, they are being processed into low value fish meal, which is used as animal feed, despite their being food-grade material suitable for human consumptiom Enzymatic hydrolysis is one of the best methods for producing value-added products as it produces protein hydrolysates with bioactive, functional and physico-chemical properties. However, despite more than 60 years of research and development, some important information relevant to the chemical engineering discipline remain lacking. This study was aimed at determining the impact of processing conditions at different stages of enzymatic hydrolysis of sardine by-products using Alcalase to produce spray dried hydrolysates. This was achieved by (i) investigating the effect of mixing speed, solids concentration and enzyme dosage on dry solids yield and protein recovery, and emulsion formation during enzymatic hydrolysis of sardine processing by-products, (ii) determining the effect of solids concentration and emulsion formation on molecular weight distribution of protein hydrolysates, (iii) investigating the effect of mixing speed and solids concentration on the viscosity and mixing regime of material during enzymatic hydrolysis, (iv) establishing the role played by processing conditions (degree of hydrolysis (OH), maltodextrin addition and inlet air temperature) on powder recovery during spray drying, and handling and storage properties of the spray dried protein hydrolysates. A complex relationship was observed between variables, where the effect of one variable was dependent on the levels of the other processing variables. Low solids concentration at low mixing speed and high enzyme dosage were required to maximise protein recovery in the aqueous phase while minimising protein loss to emulsion and sludge. Simultaneously increasing solids concentration and mixing speed did not attenuate protein loss to emulsion. The peptides in the emulsion phase are of bw value, as they are removed from the hydrolysate that is finally dried. Their recovery requires additional processing, which adds to process complexity and cost At high solids concentration, energy consumption in the first 10 minutes of hydrolysis was significantly higher than in the last 10 minutes (hydrolysis time = 60 min). The reduction in energy consumption was due to liquefaction of solids. Although viscosity was expected to decrease due to liquefaction of solids and reduction in molecular weight of proteins, it increased in the first 10 minutes of hydrolysis and remained high thereafter. This was most likely due to gel formation caused by agglomeration of proteins when their concentration in solution increases, or emulsion formation, or both. It is shown that processing conditions affected powder recovery during spray drying, and handling and storage properties. DH had the strongest influence on powder recovery, with high DH resulting in bw powder recovery. The hygroscopic nature of protein hydrolysates caused a significant amount to stick to the chamber walls. This material can be recovered easily by using appropriate mechanisms or modifications to the drying equipment, increasing powder recoveries to over 80%. The protein hydrolysates at high DH had higher water affinity and addition of maltodextrin had little effect on their moisture adsorption capacity.en_ZA
dc.description.abstractAFRIKAANSE OPSOMMING: Sardientjieprosessering se by-produkte is ’n waardevolle hulpbron wat tans ondergebruik word. Dit word huidig geprosesseer na lae waarde vismeel, wat gebruik word in dierevoer, ten spyte daarvan dat daar voedsel-graad materiaal is gepas vir menslike gebruik. Ensimatiese hidrolise is een van die beste metodes vir die produsering van waarde-byvoegende produkte omdat dit proteïenhidrolisate met die beste bio-aktiewe, funksionele, en fisio-chemiese eienskappe produseer. Ten spyte van meer as 60 jaar se navorsing en ontwikkeling, ontbreek sommige belangrike informasie relevant tot die chemiese ingenieurswese dissipline egter steeds. Hierdie studie het beoog om die impak van prosesseringkondisies by verskillende stadia van ensimatiese hidrolise van sardientjie byprodukte te bepaal, deur Alcalase te gebruik om gesproei-droogte hidrolisate te produseer. Hierdie is bereik deur (i) die effek van meng spoed, vaste stofkonsentrasie en ensiemdosering op droë vaste stofopbrengste en proteïenherwinning, en emulsieformasie gedurende ensimatiese hidrolise van sardientjieprosessering se byprodukte, te ondersoek, (ii) die effek van vaste stofkonsentrasie en emulsieformasie op molekulêre gewigverspreiding van proteïenhidrolisate te bepaal, (iii) die effek van mengspoed en vaste stofkonsentrasie op die viskositeit en mengregime van materiaal gedurende ensimatiese hidrolise te ondersoek, (iv) die rol wat deur prosesseringkondisies gespeel word vas te stel (graad van hidrolise (DH), maltodekstrien byvoeging en inlaat lugtemperatuur) op poeierherwinning gedurende sproeidroging, en hantering en verbergingeienskappe van die sproeidroog proteïenhidrolisate. ’n Komplekse verhouding is waargeneem tussen veranderlikes, waar die effek van een veranderlike afhanklik was op die vlakke van die ander prosesseringveranderlikes. Lae vaste stofkonsentrasies by lae mengspoed en hoë ensiemdosering is vereis om respons veranderlikes van belang te maksimeer, terwyl proteïenverlies aan emulsie en afskot geminimeer is. Gelyktydige verhoging van vaste stofkonsentrasie en mengspoed het nie proteïenverlies na emulsie verminder nie. Die peptides in die emulsiefase is van lae waarde, omdat hulle verwyder is van die hidrolisaat wat finaal gedroog is. Hul herwinning vereis addisionele prosessering, wat bydrae tot proseskompleksiteit en koste. Teen hoë vaste stofkonsentrasie, was energieverbruik in die eerste tien minute van hidrolise beduidend hoër as in die laaste tien minute (hidrolisetyd = 60 min). Die vermindering in energieverbruik is as gevolg van vloeibaarmaking van vaste stowwe. Al was viskositeit verwag om af te neem as gevolg van vloeibaarmaking van vaste stowwe en vermindering in molekulêre gewig van proteïene, het dit in die eerste tien minute van hidrolise verhoog en hoog gebly daarna. Dit is tien teen een as gevolg van jelformasie veroorsaak deur agglomerasie van proteïene toe hulle konsentrasie in oplossing verhoog het, of emulsieformasie, of beide. Dit is egter bewys dat prosesseringkondisies poeierherwinning gedurende sproeidroging geaffekteer het, asook hantering en verbergingeienskappe. DH het die sterkste invloed op poeierherwinning gehad, met hoë DH wat gelei het tot lae poeierherwinning. Die higroskopiese natuur van proteïenhidrolisate het ’n beduidende hoeveelheid aan die kamermure laat vas sit. Hierdie materiaal kan maklik herwin word deur gepaste meganismes of modifikasies aan die droogmakingtoerusting te gebruik, wat poeierherwinning na meer as 80% verhoog. Die proteïenhidrolisate by hoë DH het hoër wateraffiniteit en byvoeging van maltodekstrien het ʼn klein effek op hulle dampadsorpsie kapasiteit gehadaf_ZA
dc.description.versionDoctorateen_ZA
dc.format.extentxxv, 269 pages : illustrationsen_ZA
dc.identifier.urihttps://scholar.sun.ac.za/handle/10019.1/129062en_ZA
dc.language.isoen_ZAen_ZA
dc.language.isoen_ZAen_ZA
dc.publisherStellenbosch : Stellenbosch Universityen_ZA
dc.rights.holderStellenbosch Universityen_ZA
dc.subject.lcshHydrolytic enzymesen_ZA
dc.subject.lcshMixingen_ZA
dc.subject.lcshSardine industryen_ZA
dc.subject.lcshEnzymatic hydrolysisen_ZA
dc.titleThe impact of processing conditions on enzymatic protein hydrolysis performance from sardine (Sardina pilchardus) by-products using Alcalase 2.4L, and the influence on final spray dried hydrolysate powder propertiesen_ZA
dc.typeThesisen_ZA
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