Sajid Maqsood

Emerging Role of Phenolic Compounds as Natural Food Additives in Fish and Fish Products

Chemical and microbiological deteriorations are principal causes of quality loss of fish and fish products during handling, processing, and storage. Development of rancid odor and unpleasant flavor, changes of color and texture as well as lowering nutritional value in fish can be prevented by appropriate use of additives. Due to the potential health hazards of synthetic additives, natural products, especially natural antioxidants and antimicrobial agents, have been intensively examined as safe alternatives to synthetic compounds. Polyphenols (PP) are the natural antioxidants prevalent in fruits, vegetables, beverages (tea, wine, juices), plants, seaweeds, and some herbs and show antioxidative and antimicrobial activities in different fish and fish products. The use of phenolic compounds also appears to be a good alternative for sulphiting agent for retarding melanosis in crustaceans. Phenolic compounds have also been successfully employed as the processing aid for texture modification of fish mince and surimi. Thus, plant polyphenolic compounds can serve as potential additives for preventing quality deterioration or to retain the quality of fish and fish products.

Phenolic Compounds and Plant Phenolic Extracts as Natural Antioxidants in Prevention of Lipid Oxidation in Seafood: A Detailed Review

Lipid oxidation is the principal cause of quality loss in seafood, which is known to contain high amounts of polyunsaturated fatty acids. Such quality deterioration, associated with the development of off-flavor as well as lowering of nutritive value, can be retarded by incorporation of additives having antioxidative properties. The use of synthetic antioxidants has long been practiced in retarding lipid oxidation. However, due to the potential health concerns of synthetic antioxidants, polyphenolic compounds, which are found in different plants and their manufactured by-products, have been used as an alternative natural antioxidants to retard lipid oxidation in different seafood systems. Both pure phenolic compounds and crude plant phenolic extracts have been successfully used in delaying oxidation in fish muscle, fish oil, and fish oil-in-water emulsions. This article reviews in detail the phenolic antioxidants and their natural sources as well as focuses on the role of pure phenolic compounds and crude plant phenolic extracts on the prevention of lipid oxidation in different seafood systems.

Effect of pretreatment on lipid oxidation and fishy odour development in protein hydrolysates from the muscle of Indian mackerel.

Impact of different pretreatments on chemical compositions of Indian mackerel mince was studied. Mince prepared using washing/membrane removal/alkaline solubilisation process (W-MR-Al) contained the lowest remaining myoglobin and haem iron content and also showed the lowest total lipid and phospholipid contents. When mince and W-MR-Al were hydrolysed using Alcalase for up to 120 min, a higher degree of hydrolysis (DH) was found in W-MR-Al after 30 min of hydrolysis. Furthermore, hydrolysate from W-MR-Al had lower peroxide value (PV), thiobarbituric acid reactive substances (TBARS) and non-haem iron content throughout hydrolysis period (P<0.05). When hydrolysate powder produced from mince and W-MR-Al (0-0.3%w/v) were fortified in milk, the former resulted in the lower likeness score (P<0.05) at all levels used. The addition of the latter, for up to 0.2%, had no effect on likeness of all attributes, compared with milk without fortification (P>0.05). Therefore, the appropriate pretreatment of mince yielded hydrolysate with lower fishy odour.

Effect of Kiam (Cotylelobium lanceolatum Craib) Wood Extract on the Haemoglobin-Mediated Lipid Oxidation of Washed Asian Sea Bass Mince

IntroductionEffect of ethanolic kiam wood extract (EKWE; 12 0.05% and 0.1%, w/w) on the retardation of haemoglobin-mediated lipid oxidation of washed Asian sea bass mince added without and with menhaden oil stored in ice up to 10 days was investigated.Results and discussionSamples containing haemoglobin had the highest peroxide value (PV) within the first 8 days and possessed the greater amount of thiobarbituric acid-reactive substances (TBARS), compared to those added with no haemoglobin (P < 0.05), regardless of 5% menhaden oil addition. Incorporation of 5% (v/w) menhaden oil to the washed mince had no impact on the formation of PV and TBARS, compared with oil-free samples during the storage (P > 0.05). With addition of EKWE, lipid oxidation in washed mince added with haemoglobin and menhaden oil was retarded, especially when the higher level (0.1%; w/w) was used, as evidenced by lowered PV and TBARS. Formation of volatile lipid oxidation compounds was retarded in the sample containing oil and haemoglobin and treated with 0.1% EKWE, compared with that without the addition of EKWE after 10 days of storage in ice (P < 0.05).ConclusionSensory analysis revealed that samples containing haemoglobin without and with oil added had the highest intensity of fishy odour, compared to those treated with EKWE (0.05% and 0.1%) and the control sample (washed mince; P < 0.05). Thus, EKWE, especially at a level of 0.1%, could serve as a potential natural antioxidant in prevention of lipid oxidation and retardation of development of fishy odour and volatile lipid oxidation compounds in washed mince during iced storage.

Antioxidant activity and inhibitory effects of lead (Leucaena leucocephala) seed extracts against lipid oxidation in model systems

Antioxidant activity of brown lead (Leucaena leucocephala) seed extracts with and without prior chlorophyll removal was studied in comparison with mimosine. Both extracts showed similar hydroxyl radical (HO•) scavenging activity, hydrogen peroxide (H2O2) scavenging activity, singlet oxygen inhibition and hypochlorous acid (HOCl) scavenging capacity (p > 0.05). Nevertheless, the extract without prior chlorophyll removal had higher oxygen radical absorbance capacity than that with prior chlorophyll removal (p < 0.05). Generally, lead seed extracts with and without prior chlorophyll removal possessed a lower antioxidant activity, compared with mimosine. When lead seed extract without prior chlorophyll removal (100 and 200 ppm) was used in different lipid oxidation model systems, including β-carotene-linoleic acid and lecithin liposome systems, the preventive effect toward lipid oxidation was dose-dependent. At the same level of use, mimosine exhibited a higher efficacy in prevention of lipid oxidation in both systems as indicated by the lower increases in thiobarbituric acid reactive substances. A similar result was obtained in minced mackerel. Therefore, lead seed extract containing mimosine could act as a natural antioxidant to prevent lipid oxidation in foods.

Characteristics and gel properties of gelatin from goat skin as affected by pretreatments using sodium sulfate and hydrogen peroxide

BACKGROUND Goat skin can be used as an alternative raw material for gelatin production, in which pretreatment conditions can determine the characteristics or properties of the resulting gelatin. The present study aimed to investigate the effect of pretreatment using sodium sulfate (Na2SO4) and hydrogen peroxide (H2O2) on properties of goat skin gelatin. RESULTS Pretreatment of skin using Na2SO4 (0-1 mol L(-1)) increased the yield of gelatin in a concentration-dependent manner. When skins with prior Na2SO4 treatment were bleached using H2O2 (0-2 mol L(-1)), the resulting gelatin showed higher yield and gel strength than those without prior Na2SO4 treatment. All gelatins had α-chain as a major component, followed by β-chain. The degradation induced by H2O2 was lower in gelatin with prior Na2SO4 treatment. L* values increased with increasing H2O2 concentrations (P < 0.05) due to the bleaching effect of H2O2. With Na2SO4 and H2O2 pretreatments, gelatin gel had a finer and more ordered microstructure. Gelatin had an imino acid content of 217 residues/1000 residues with gelling and melting temperature of 22.49 and 32.28 °C, respectively. CONCLUSION The optimal pretreatment conditions for gelatin extraction from goat skin included soaking the skin in 0.75 mol L(-1) NaOH, followed by treatment using 0.75 mol L(-1) Na2SO4 and subsequent bleaching with 2 mol L(-1) H2O2. This resulted in gelatin with superior quality to the untreated counterpart.

Identification of novel dipeptidyl peptidase IV (DPP-IV) inhibitory peptides in camel milk protein hydrolysates

Nine novel dipeptidyl peptidase IV (DPP-IV) inhibitory peptides (FLQY, FQLGASPY, ILDKEGIDY, ILELA, LLQLEAIR, LPVP, LQALHQGQIV, MPVQA and SPVVPF) were identified in camel milk proteins hydrolysed with trypsin. This was achieved using a sequential approach combining liquid chromatography tandem mass spectrometry (LC-MS/MS), qualitative/quantitative structure activity relationship (QSAR) and confirmatory studies with synthetic peptides. The most potent camel milk protein-derived DPP-IV inhibitory peptides, LPVP and MPVQA, had DPP-IV half maximal inhibitory concentrations (IC50) of 87.0 ± 3.2 and 93.3 ± 8.0 µM, respectively. DPP-IV inhibitory peptide sequences identified within camel and bovine milk protein hydrolysates generated under the same hydrolysis conditions differ. This was linked to differences in enzyme selectivity for peptide bond cleavage of camel and bovine milk proteins as well as dissimilarities in their amino acid sequences. Camel milk proteins contain novel DPP-IV inhibitory peptides which may play a role in the regulation of glycaemia in humans.

Gel Strengthening Effect of Wood Extract on Surimi Produced from Mackerel Stored in Ice

The effect of ethanolic kiam wood extract (EKWE) and commercial tannin (CT) on the gel properties of surimi produced from mackerel (Rastrelliger kanagurta) stored in ice for different times (0 to 12 d) was studied. During 12 d of iced storage, pH, total volatile base (TVB), trimethylamine (TMA), and trichloroacetic acid (TCA)-soluble peptide contents as well as thiobarbituric acid-reactive substances (TBARS) of mackerel mince increased while myosin heavy chain (MHC) band intensity decreased continuously (P < 0.05). The result suggested that deterioration, protein degradation, and lipid oxidation proceeded with increasing storage time. For corresponding surimi, TVB and TMA were almost removed and TBARS and TCA soluble peptide contents were decreased. Conversely, MHC became more concentrated. Decreases in gel-forming ability of surimi were observed when fish used as raw material were stored in ice for a longer time, regardless of EKWE or CT addition. Whiteness of surimi gel decreased and expressible moisture increased especially when the storage time increased. However, superior breaking force and deformation of surimi gel with 0.15% EKWE or 0.30% CT added, compared to those of the control gel were observed during the first 6 d of the storage. Thereafter, EKWE and CT had no gel enhancing effect on surimi. Therefore, freshness was a crucial factor determining gel enhancing ability of EKWE or CT toward mackerel surimi.

Characteristics and gel properties of gelatin from goat skin as affected by spray drying

ABSTRACT Gelatin powder from goat skin prepared by spray drying at various inlet temperatures (160–200°C) was characterized. Predominant particle sizes were in the range of 4.65–5.14 µm. Gelatin powder was mostly concave in shape with varying sizes, depending on inlet temperatures used. All gelatin powders were creamy whitish. Powder generally became more yellowish as the inlet temperature of spray drying increased (p < 0.05). All gelatins contained α-chain as the dominant constituent. Nevertheless, α-chain of gelatin spray dried at 200°C was almost disappeared. Gel strength of gelatin decreased as the inlet temperature for spray drying increased (p < 0.05). Gelatin with inlet temperature of 160°C had the highest gel strength (260 g) (p < 0.05), which was comparable to the freeze-dried counterpart (268 g) (p > 0.05). Goat skin gelatin spray dried with inlet temperatures of 160 or 180°C had higher gel strength than commercial bovine gelatin (p < 0.05). All gelatins had solubility greater than 90% in the wide pH ranges (1–10). Therefore, spray drying with appropriate inlet temperature could be an effective means for production of gelatin powder from goat skin, exhibiting the properties equivalent to commercial bovine gelatin.

Retardation of quality changes in camel meat sausages by phenolic compounds and phenolic extracts

Impact of tannic acid (TA), date seed extract (DSE), catechin (CT) and green tea extract (GTE) on lipid oxidation, microbial load and textural properties of camel meat sausages during 12 days of refrigerated storage was investigated. TA and CT showed higher activities in all antioxidative assays compared to DSE and GTE. Lipid oxidation and microbial growth was higher for control sausages when compared to other samples. TA and CT at a level of 200 mg/kg were more effective in retarding lipid oxidation and lowering microbial count (P < 0.05). Sausages treated with TA and DSE were found to have higher hardness, gumminess and chewiness values compared to other treatments (P < 0.05). Addition of different phenolic compounds or extract did not influence the sensory color of sausages. Furthermore, sensory quality was also found to be superior in TA and CT treated sausages. Therefore, pure phenolic compounds (TA and CT) proved to be more effective in retaining microbial and sensorial qualities of camel meat sausages compared to phenolic extracts (GTE and DSE) over 12 days of storage at 4°C.