Didem Sutay KOCABAŞ, Eren YURTDAŞ, Ayşe Nur DEMİR

VALORIZATION OF OLIVE-OIL INDUSTRY SOLID WASTE: STATISTICAL OPTIMIZATION OF ALKALINE EXTRACTION CONDITIONS FOR LIGHT-COLOURED HEMICELLULOSES

Zeytinyağı üretim sürecinin yan-ürünü olan zeytin katı atığı (ZKA), çok düflük ekonomik değere sahip birlignoselülozik materyaldir. ZKA'nın hemiselüloz fraksiyonu, birçok endüstriyel uygulama için hammadde olarakkullanım potansiyeline sahiptir. Bu çalıflmanın temel amacı, ZKA'dan mümkün olan en yüksek ham hemiselülozözütleme verimine ulaflmak için bir alkali özütleme tekniğinin istatistiksel olarak gelifltirilmesi ve bunun yanındasiyah hemiselülozların renginin açılmasıdır. Optimizasyon için Box-Behnken Tasarımı temelli tepki yüzey metodolojisikullanılmıfltır. Optimum hemiselüloz özütleme koflulları %19,3 (a/h) alkali (KOH) konsantrasyonu, 1,3 mm partikülbüyüklüğü, 25,3 saat özütleme süresi, %1 (a/h) MgSO4konsantrasyonu, %6,4 (h/h) H2O2konsantrasyonu ve 60°Csıcaklık olarak tespit edilmifltir. Bu koflullardaki en yüksek deneysel hemiselüloz verimi %35,6±0,5 olup, teorikdeğer olan %31,2 ile uyumludur. Sonuç olarak, özütleme verimi %21,7'den %35,6'ya (a/a) çıkarılmıfltır. Optimumkoflullarda özütlenen hemiselülozların renk değerleri (L*,a*,b*) sırasıyla 31,69±0,28, -2,90±0,04 ve 5,49±0,04 olarakbulunmufltur. Çalıflmanın sonuçları, gıda paketleme uygulamaları için biyobozunur plastikler ve ksilooligosakkaritlergibi endüstriyel öneme sahip katma değerli ürünlere dönüfltürülme potansiyeline sahip açık renkli ZKAhemiselülozlarının izole edilmesi için yol göstermektedir.

ZEYTİNYAĞI ENDÜSTRİSİ KATI ATIĞININ DEĞERLENDİRİLMESİ: AÇIK RENKLİ HEMİSELÜLOZLAR İÇİN ALKALİ ÖZÜTLEME KOŞULLARININ İSTATİSTİKSEL OPTİMİZASYONU

Olive solid waste (OSW), the by-product of olive oil production process, is a lignocellulosic material with very loweconomic value. The hemicellulose fraction of OSW has a potential to be used as a raw material for several industrialapplications. The main objective of the present work was to statistically develop an alkaline hemicellulose extractionprocedure to achieve the highest possible crude hemicellulose extraction yield from OSW with concurrent effortsto lighten the colour of black hemicelluloses. Box-Behnken Design based response surface methodology wasemployed for optimization. The optimum hemicellulose extraction conditions were found as 19.3% (w/v) alkaline(KOH) concentration, 1.3 mm particle size, 25.3 h extraction time, 1% (w/v) MgSO4concentration, 6.4% (v/v) H2O2concentration and 60°C temperature. The maximum experimental hemicelluloses yield at this condition was35.6±0.5% which is in agreement with the predicted yield value of 31.2%. As a result, the extraction yield has beenincreased from 21.7% to 35.6% (w/w). The colour values (L*,a*,b*) of hemicelluloses extracted at optimum conditionswere predicted as 31.69±0.28, -2.90±0.04 and 5.49±0.04, sequentially. The findings of this study demonstrated theroute for isolation of light-coloured OSW hemicelluloses that have potential for conversion into industrially importantvalue-added products such as biodegradable plastics for food packaging applications and xylooligosaccharides.

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