Effect of Olive Leaf (Olea europaea L.) Extract-Enriched Coating on the Sensory and Microbial Quality of European Seabass (Dicentrarchus labrax) Fillets during Cold Storage

Abstract

This study researched the effects of a gelatin-based coating containing ethanolic olive leaf extract (EOLE) at 1%, 2%, and 3% on the quality of European sea bass (Dicentrarchus labrax) fillets stored at +4 °C. Fish fillets were coated by immersion, and sensory, physicochemical, and microbiological analyses were conducted during cold storage. GC–MS results showed that di-(9-octadecenoyl)-glycerol (48.08%), dipalmitin (24.68%), glycidol stearate (11.69%), and 15-hydroxypentadecanoic acid (5.01%) were the main components of EOLE. Sensory scores increased with higher coating concentrations. The highest texture score was recorded in the 3% EOLE group (p < 0.05). No significant changes were determined among groups for pH and color parameters (L*, a*, b*) on the same storage days (p > 0.05). These changes were mainly related to storage time. Total viable bacterial count and psychrotrophic bacterial counts increased during storage, but no significant differences were found between the experimental groups (p > 0.05). Coliform bacteria were detected in the control group on day 2. However, total coliform counts in the EOLE-coated groups remained below the detection limit. In conclusion, gelatin-based coating containing ethanolic olive leaf extract maintained sensory acceptability, improved texture, and showed the potential to limit coliform growth in the early stages of storage.

Keywords

• Seafood
• edible coating
• agricultural by-product
• sustainability
• food safety

Supporting Institution

TÜBİTAK

Project Number

1919B012433292

Ethical Statement

Sensory evaluation involving trained panelists was approved by the Institutional Ethics Committee (Approval No: 2025-YÖNP-0034).

Thanks

This study was supported by the Scientific and Technological Research Council of Türkiye (TÜBİTAK) under the 2209-A – University Students Research Projects Support Program (Project No:1919B012433292).

Zeytin Yaprağı (Olea europaea L.) Ekstraktı ile Zenginleştirilmiş Kaplamanın Soğuk Depolama Süresince Avrupa Levreği (Dicentrarchus labrax) Filetolarının Duyusal ve Mikrobiyal Kalitesi Üzerine Etkisi

Abstract

Bu çalışmada, %1, %2 ve %3 oranlarında etanolik zeytin yaprağı ekstraktı (EOLE) içeren jelatin bazlı kaplamanın, +4 °C’de depolanan Avrupa levreği (Dicentrarchus labrax) filetolarının kalitesi üzerindeki etkileri araştırılmıştır. Balık filetoları daldırma yöntemiyle kaplanmış ve soğuk depolama süresince duyusal, fizikokimyasal ve mikrobiyolojik analizler gerçekleştirilmiştir. GC–MS analiz sonuçlarına göre EOLE’nin ana bileşenlerinin di-(9-oktadekenoyl)-gliserol (%48,08), dipalmitin (%24,68), glisidol stearat (%11,69) ve 15-hidroksipentadekanoik asit (%5,01) olduğu belirlenmiştir. Kaplama konsantrasyonu arttıkça duyusal puanların yükseldiği saptanmış, en yüksek tekstür puanı %3 EOLE grubunda elde edilmiştir (p < 0,05). Aynı depolama günlerinde gruplar arasında pH ve renk parametreleri (L*, a*, b*) bakımından istatistiksel olarak anlamlı bir fark olmamıştır (p > 0,05). Bu değişimlerin esas olarak depolama süresine bağlı olduğu tespit edilmiştir. Toplam canlı bakteri ve psikrotrofik bakteri sayıları depolama süresince artış göstermiş, ancak deney grupları arasında anlamlı bir fark bulunmamıştır (p > 0,05). Koliform bakteriler 2. günde yalnızca kontrol grubunda tespit edilirken, EOLE ile kaplanan gruplarda toplam koliform sayıları tespit limitinin altında kalmıştır. Sonuç olarak, etanolik zeytin yaprağı ekstraktı (EOLE) içeren jelatin bazlı kaplamanın duyusal kabul edilebilirliği koruduğu, tekstürel özellikleri iyileştirdiği ve depolamanın erken evrelerinde koliform bakterilerin gelişimini sınırlama potansiyeli gösterdiği belirlenmiştir.

Keywords

• Deniz ürünleri
• yenilebilir kaplama
• tarımsal yan ürün
• sürdürülebilirlik
• gıda güvenliği

Project Number

1919B012433292

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