Elma posasında selüloz ve nanoselüloz takviye ajanlarının üretimi ve alçak yoğunluk polietilen esaslı biyobozunur gıda ambalaj malzemelerinin geliştirilmesinde kullanımı
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Tarih
2020
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Yayıncı
Ege Üniversitesi, Fen Bilimleri Enstitüsü
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
Bu tez çalışmasında; plastik esaslı ambalaj atıklarının yarattığı çevresel sorunlara çözüm üretmek amacıyla biyo-baz içeriğine sahip, biyobozunur özellikte biyokompozit ve nanokompozit ambalaj malzemelerinin ekstrüzyon tekniği ile üretimi sağlanmıştır. Çalışma; (i) elma posasından takviye ajanlarının eldesi, (ii) alçak yoğunluk polietilen (AYPE) esaslı biyokompozit ve nanokompozit ambalaj malzemelerinin ekstrüzyon tekniği ile üretimi ve (iii) gıda ambalajlama uygulamaları olmak üzere toplam 3 aşamada gerçekleştirilmiştir. İlk aşamada kurutulmuş ve öğütülmüş elma posasından, yanıt yüzey metodu (RSM) kullanılarak belirlenen optimum ekstraksiyon koşullarında %27,96 verimle, yüksek alfa-selüloz miktarı (%85,31) ve beyazlık indisine (47,79) sahip selüloz eldesi sağlanmıştır. Selülozdan ise asit hidrolizi ve ultrasonifikasyon işlemleri ile nanoselüloz üretilerek, örneklerin kimyasal yapısındaki değişim (FTIR), kristallik derecesi (XRD) ve yüzey morfolojisi (SEM ve AFM), incelenmiştir. Elma posasına uygulanan kimyasal işlemlerin hemiselüloz ve lignin gibi safsızlıkların uzaklaştırılmasında etkili olduğu belirlenmiştir. XRD analizi sonucu nanoselülozun yüksek kristallik derecesine sahip (%78) olduğu, AFM analizi sonucu ise çubuk/iğne şeklinde selüloz nanokristallerine ait yapıların varlığı saptanmıştır. ikinci aşamada elma posasından elde edilen elma posası tozu, selüloz ve nanoselüloz, AYPE matrise takviye ajanı olarak eklenerek, ekstrüzyon yöntemi ile biyokompozit ve nanokompozit kompaund ve ambalaj filmleri üretilmiştir. Takviye ajanlarının kompozit malzemenin renk, mekanik, kimyasal, ısıl vb. özelliklerine etkisi değerlendirilmiştir. AYPE esaslı biyokompozit malzemelerde elma posası tozu ve selüloz konsantrasyonundaki artışa bağlı olarak malzemenin mekanik mukavemeti ve transparanlığı azalmış, filmlerin örtücülüğü artmıştır. Simüle toprak altında 12 ay boyunca bekletilen örneklerde takviye ajanı konsantrasyon artışına bağlı olarak malzemede ağırlık kaybının arttığı belirlenmiştir. Elma posası ve selüloz (%10-15) katkılı biyokompozit malzemelerde yaklaşık %5, %1 nanoselüloz içeren nanokompozit ambalaj malzemelerinde ise yaklaşık %1,5 oranında ağırlık kaybı meydana gelmiştir. Üçüncü ve son aşamada seçili ambalaj malzemelerinin gıda ambalaj materyali olarak, az işlem görmüş ıspanağın (Spinacia oleracea L. cv. Kuzu) ambalajlanmasında kullanım potansiyeli incelenmiştir. Az işlem görmüş ıspanak pasif modifiye atmosferde AYPE (kontrol) ve %1 nanoselüloz içeren nanokompozit ambalaj malzemeleri ile +4 °C‘de 17 gün depolanmıştır. Depolama süresince, ıspanağın kendine özgü yeşil renginde, toplam klorofil ve askorbik asit miktarında azalma, pH değeri ve ağırlık kaybında ise artış saptanmıştır. Her iki ambalaj grubunda da ıspanakların mikrobiyolojik açıdan 17 gün tüketime uygun olduğu belirlenmiştir. Nanokompozit ambalaj malzemesinde depolanan ıspanakların, kontrol grubunda depolanan örneklere nazaran duyusal açıdan kabul edilebilirliğinin yüksek olduğu saptanmıştır. Elma posasından elde edilen selüloz ve nanoselüloz gibi katma değeri yüksek ürünlerin takviye ajanı olarak AYPE hammaddeye biyo-baz içeriği ve biyobozunma davranışı kazandırılmasında etkili olduğu ve gıda ambalaj materyali olarak kullanım potansiyeline sahip olduğu sonucuna varılmıştır.
In this thesis, the production of biocomposite and nanocomposite packaging materials with bio-based content and biodegradable properties were produced by the extrusion method as a solution to environmental problem of plastic-based packaging waste. The study was carried out in three stages: (i) the production of reinforcing agents from apple pomace, (ii) the production of low-density polyethylene based (LDPE) biocomposite and nanocomposite packaging materials by an extrusion method and (iii) food packaging applications. Stage 1, involved the production of cellulose with a high alpha-cellulose content (85.31%) and a whiteness index (47.79) from dried and ground apple pomace under optimum extraction conditions, determined by using the response surface method (RSM), with a yield of 27.96%. Then, nanocellulose was produced from the cellulose through acid hydrolysis and ultrasonication processes. The chemical structure of the samples (FTIR), degree of crystallinity (XRD) and the surface morphology (SEM and AFM) change in were examined. It was found that chemical treatments applied to apple pomace were effective in the removal of impurities such as hemicellulose and lignin. XRD analysis results were indicated that the nanocellulose had a high degree of crystallinity (78%), while the AFM analysis revealed rod/needle-like shaped cellulose nanocrystals. In stage 2, the apple pomace powder, cellulose and nanocellulose obtained from apple pomace were added as reinforcing agents to the LDPE matrix to produce biocomposite and nanocomposite compounds and packaging films. The effect of reinforcing agents on the color and mechanical, chemical, thermal, etc. properties of the composite material was assessed. Due to the increased apple pomace powder and cellulose concentrations in the LDPE-based biocomposite materials, their mechanical strength and transparency decreased, and the opacity of the films increased. In biodegradability analysis, the samples were kept in simulated soil over 12 months, it was found that the weight loss of the material increased with the increase in reinforcing agents concentrations. Approximately 5% loss of weight was noted in the biocomposite materials containing apple pomace powder and cellulose (10–15%), along with weight loss of approximately 1.5% occurring in nanocomposite packaging materials containing 1% nanocellulose. In the final stage, the potential usage of the selected packaging materials effect on the packaging of minimally processed spinach (Spinacia oleracea L. cv. Kuzu), were investigated. The minimally processed spinach samples were stored in a passive modified atmosphere with LDPE (control) and nanocomposite packaging materials containing 1% nanocellulose at +4°C for 17 days. During storage, a decrease was observed in the specific green color of the spinach, and in the total amount of chlorophyll and ascorbic acid, along with an increase in the pH value and weight loss. It was found that the spinach stored in both packaging materials was microbiologically acceptable for consumption over 17 days, although it was found that the spinach stored in the nanocomposite packaging material had higher scores for sensory acceptability than the control group. It was concluded that high value-added products such as cellulose and nanocellulose obtained from apple pomace were effective in providing bio-based content and biodegradation behavior to LDPE as reinforcing agents, and showed high potential to be used as food packaging materials.
In this thesis, the production of biocomposite and nanocomposite packaging materials with bio-based content and biodegradable properties were produced by the extrusion method as a solution to environmental problem of plastic-based packaging waste. The study was carried out in three stages: (i) the production of reinforcing agents from apple pomace, (ii) the production of low-density polyethylene based (LDPE) biocomposite and nanocomposite packaging materials by an extrusion method and (iii) food packaging applications. Stage 1, involved the production of cellulose with a high alpha-cellulose content (85.31%) and a whiteness index (47.79) from dried and ground apple pomace under optimum extraction conditions, determined by using the response surface method (RSM), with a yield of 27.96%. Then, nanocellulose was produced from the cellulose through acid hydrolysis and ultrasonication processes. The chemical structure of the samples (FTIR), degree of crystallinity (XRD) and the surface morphology (SEM and AFM) change in were examined. It was found that chemical treatments applied to apple pomace were effective in the removal of impurities such as hemicellulose and lignin. XRD analysis results were indicated that the nanocellulose had a high degree of crystallinity (78%), while the AFM analysis revealed rod/needle-like shaped cellulose nanocrystals. In stage 2, the apple pomace powder, cellulose and nanocellulose obtained from apple pomace were added as reinforcing agents to the LDPE matrix to produce biocomposite and nanocomposite compounds and packaging films. The effect of reinforcing agents on the color and mechanical, chemical, thermal, etc. properties of the composite material was assessed. Due to the increased apple pomace powder and cellulose concentrations in the LDPE-based biocomposite materials, their mechanical strength and transparency decreased, and the opacity of the films increased. In biodegradability analysis, the samples were kept in simulated soil over 12 months, it was found that the weight loss of the material increased with the increase in reinforcing agents concentrations. Approximately 5% loss of weight was noted in the biocomposite materials containing apple pomace powder and cellulose (10–15%), along with weight loss of approximately 1.5% occurring in nanocomposite packaging materials containing 1% nanocellulose. In the final stage, the potential usage of the selected packaging materials effect on the packaging of minimally processed spinach (Spinacia oleracea L. cv. Kuzu), were investigated. The minimally processed spinach samples were stored in a passive modified atmosphere with LDPE (control) and nanocomposite packaging materials containing 1% nanocellulose at +4°C for 17 days. During storage, a decrease was observed in the specific green color of the spinach, and in the total amount of chlorophyll and ascorbic acid, along with an increase in the pH value and weight loss. It was found that the spinach stored in both packaging materials was microbiologically acceptable for consumption over 17 days, although it was found that the spinach stored in the nanocomposite packaging material had higher scores for sensory acceptability than the control group. It was concluded that high value-added products such as cellulose and nanocellulose obtained from apple pomace were effective in providing bio-based content and biodegradation behavior to LDPE as reinforcing agents, and showed high potential to be used as food packaging materials.
Açıklama
Anahtar Kelimeler
Elma Posası, Selüloz, Selüloz Nanokristalleri, Biyokompozit, Nanokompozit, Az İşlem Görmüş Ispanak, Pasif Modifiye Atmosferde Ambalajlama, Apple Pomace, Cellulose, Cellulose Nanocrystals, Biocomposite, Nanocomposite, Minimally Processed Spinach, Passive Modified Atmosphere Packaging
