Effect of Pretreatments and Defatting of Seabass Skins on Properties and Fishy Odor of Gelatin

Abstract

The impact of different pretreatments and defatting processes of seabass skins on fishy odor and other properties of gelatin was investigated. Skin pretreated with 0.05 M citric acid, followed by defatting using 30% isopropanol (G‐Ci‐Def) had the lowest residual phospholipid content (P < 0.05). Nevertheless, G‐Ci‐Def had a lower yield and gel strength, compared to those from skins pretreated with acetic acid (G‐Ac) or citric acid (G‐Ci) (P < 0.05). All gelatins contained α‐chains as the predominant component as indicated by SDS‐PAGE. G‐Ci‐Def showed the highest L* value and the lowest a*, b*, ΔE* and ΔC* values, compared to the other gelatins (P < 0.05). All gelatins were sponge or coral‐like in structure but varied in patterns as evaluated by scanning electron microscopy. The lower fishy odor associated with lower amounts of most volatile compounds was found in G‐Ci‐Def, compared to other gelatins. Therefore, gelatin with negligible fishy odor could be prepared from citric acid pretreated and isopropanol defatted skin. Practical Applications Seabass skins are potential raw materials for production of collagen, gelatin and bioactive protein hydrolysates. Pretreatment and defatting of seabass skin plays a significant role in the reduction of lipids, especially membrane phospholipids. Pretreatment using citric acid and defatting using isopropanol of skin prior to gelatin extraction could lower lipid oxidation, volatile compounds, and fishy odor. Gelatin prepared could be widely used in foods with minimal effect on sensory attributes.

Hydrolyzed collagen from porcine lipase‐defatted seabass skin: Antioxidant, fibroblast cell proliferation, and collagen production activities

“…Thereafter, the samples were determined for lipid contents as per the method of Sae‐leaw and Benjakul (). For positive control, swollen skins were defatted for 1 hr with (30%, v/v) isopropanol, exhibiting the higher efficacy in defatting seabass skin as compared to other conditions (type of solvent and defatting time) (Sae‐leaw et al, ). The PPL concentration that produced the highest lipid reduction was selected for use in further experiments.…”

“…Fifteen trained panelists were recruited. Prior to evaluation, the panelists were regularly trained with standards as tailored by Sae‐leaw et al (). Eighteen‐day ice‐stored non‐defatted seabass skin was hydrolyzed with papain (0.3 unit/g dry matter) and the resulting HC was used to determine the standard level of fishy odor.…”

“…Nevertheless, seabass skin contains high content of lipids, which are prone to oxidation during extraction or hydrolysis at elevated temperatures. This directly contributes to the formation of offensive odor/flavor, particularly fishy odor in the finished products (Sae‐leaw, Benjakul, & O'Brien, ). Defatting of fish skin is an important step prior to the preparation and utilization of gelatin or HC.…”

“…Defatting of fish skin is an important step prior to the preparation and utilization of gelatin or HC. Sae‐leaw et al () documented that seabass skin defatted with isopropanol yielded gelatin with reduced fat content and fishy odor intensity. Nevertheless, the use of solvents is limited due to cost and the presence of unwanted residues in the products.…”

Volatile components of American silver carp analyzed by electronic nose and MMSE‐GC‐MS‐O

“…Based on the results of volatile compound detection, the sex and geographical locations of sea urchin seeds were determined. Sae‐Leaw, Benjakul, and O'Brien () investigated the volatile compounds of seabass skins, and prepared a gelatin with negligible fishy odor. To control the overall flavor map of food, electronic nose combined with GC‐MS is often used to distinguish different odor components, while the chemical components of odor are typically evaluated in detail by GC‐MS/GC‐MS‐O (Huang et al, ).…”