Inhibitory effect of rice bran extract on polyphenol oxidase of potato and banana

Rice bran was extracted with water and its effects on potato and banana polyphenol oxidase (PPO) were investigated. Rice bran extract (RBE), conc. 0.3 g mL^?1, exhibited PPO inhibition in potato and banana PPO with % inhibition of 69.31% and 47.63%, respectively (P ≤ 0.05). RBE showed a concentration‐dependent inhibition on potato and banana PPO. RBE (conc. 0.3 g mL^?1) inhibited potato PPO higher than ascorbic acid, citric acid, NaCl and EDTA (final conc. 20 mg L^?1); and it also inhibited banana PPO higher than citric acid, NaCl and EDTA (final conc. 20 mg L^?1), respectively. The combination of RBE with citric acid or ascorbic acid appeared to be additive inhibitory effect on banana and potato PPO. Kinetic study of the inhibition on potato and banana PPO by RBE showed that RBE was a mixed‐type inhibitor; however, RBE appeared to be able to act directly on enzyme structure rather than substrate structure.     

Alginate–calcium coating incorporating nisin and EDTA maintains the quality of fresh northern snakehead (Channa argus) fillets stored at 4 °C

BACKGROUND: Antimicrobial packaging is a novel food packaging technology for controlling the growth of food‐borne pathogens or spoilage bacteria in ready‐to‐eat food products. Fresh fish are highly perishable foodstuffs and are extremely susceptible to microbial activities. An alginate–calcium coating incorporating nisin and ethylenediaminetetraacetic acid (EDTA) was used as an antimicrobial packaging to maintain the quality of northern snakehead (Channa argus) at refrigeration temperature (4 ± 1 °C). Northern snakehead fillets were left untreated (CK), or were treated with 1000 IU mL^?1 nisin and 150 µg mL^?1 EDTA (T1), alginate–calcium coating (T2), or alginate–calcium coating incorporating 1000 IU mL^?1 nisin and 150 µg mL^?1 EDTA (T3). RESULTS: All treatments retarded the decay of the fish fillets. T1 more efficiently inhibited the growth of total viable mesophilic bacteria (P < 0.05) and total psychrophilic bacteria (P > 0.05) than did T2 or T3. Coating treatments predominantly reduced chemical spoilage, reflected in total volatile base nitrogen (P > 0.05), trimethylamine (P > 0.05), pH (P < 0.05), and thiobarbituric acid (P < 0.05), retarded water loss (P < 0.05), and increased the overall sensory scores of fish fillets (P < 0.05) compared with those of T1. There was no significant difference between the coating treatments T2 and T3 (P > 0.05). CONCLUSION: Alginate–calcium coating treatments efficiently enhanced the quality of northern snakehead fillets during storage. Copyright © 2009 Society of Chemical Industry     

Optimisation of hydrolysis of purple sea urchin (Strongylocentrotus nudus) gonad by response surface methodology and evaluation of in vitro antioxidant activity of the hydrolysate

BACKGROUND: Hydrolysates prepared from sea urchin (Strongylocentrotus nudus) gonad by enzymatic treatment showed strong 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity and reducing power. RESULTS: Hydrolysis of S. nudus gonad by the commercial protease papain was optimised for maximum degree of hydrolysis (DH) and trichloroacetic acid‐soluble peptide index (TCA‐SPI) using response surface methodology. Results showed that the optimal conditions were the following: temperature of 48.83 °C, pH of 6.92, enzyme‐to‐substrate ratio of 3143 U g^?1, and substrate concentration of 83.5 g L^?1. Under these conditions, a DH of 27.96 ± 0.54% and a TCA‐SPI of 57.32 ± 0.63% were obtained. The hydrolysate prepared in the optimal conditions was fractionated by an ultra‐filtration system and the resultant fraction below 10 kDa was found to effectively scavenge hydroxyl radical (EC₅₀ = 13.29 ± 0.33 mg mL^?1) and hydrogen peroxide (EC₅₀ = 16.40 ± 0.37 mg mL^?1), inhibit lipid peroxidation (EC₅₀ = 11.05 ± 0.62 mg mL^?1), chelate Fe²⁺ (EC₅₀ = 7.26 ± 0.44 mg mL^?1), and protect mice macrophages against death induced by tert‐butyl hydroperoxide. CONCLUSION: Hydrolysates prepared from S. nudus gonad have the potential to be applied as natural antioxidant agents. Copyright © 2012 Society of Chemical Industry     

Antioxidant activities of different Teucrium montanum L. Extracts

The sequential extraction of Teucrium montanum L. was realised with five solvents of different polarities (70% methanol, petroleum ether, chloroform, ethyl acetate, and n‐butanol) and HPLC method was used for identification of phenolic compounds. The total phenolic content of the extracts was determined spectrophotometrically according to the Folin–Ciocalteau procedure and range from 0 to 296 mg g^?1. The antioxidant activity of extracts was tested by measuring their ability to scavenge reactive hydroxyl radical during the Fenton reaction, using electron spin resonance (ESR) spectroscopy. Moreover, the influence of these extracts on lipid peroxyl radicals obtained during lipid peroxidation of: (1) sunflower oil (37 °C, 3 h) induced by 4,4′‐azobis(4‐cyanovaleric acid) (ACVA) and (2) liposomes induced by 2,2′‐azobis(2‐amidino‐propane)dihydrochloride (AAPH) was studied. n‐Butanol extract, because of the highest content of total phenolic compounds (296 mg g^?1) had the best antioxidant activity (100% at 0.16 mg mL^?1 in Fenton reaction system; 90.57% at 5 mg mL^?1 in system I; 100% at 5 mg mL^?1 in system II).     

Tyrosinase inhibition by water and ethanol extracts of a far eastern sea cucumber, Stichopus japonicus

BACKGROUND: Tyrosinase plays a key role in hyperpigmentaion and enzymatic browning. The present study was aimed at investigating the inhibitory effects of water and 70% aqueous ethanol extracts of Stichopus japonicus, a sea cucumber long consumed as a tonic food and traditional medicine, on the diphenolase activity of tyrosinase. RESULTS: In the tyrosinase inhibition study, high‐performance liquid chromatography completely separated L ‐3,4‐dihydroxyphenylalanine and dopachrome from other compounds present in the extracts, and provided more reliable results than the commonly used spectrophotometry. The ethanol extract (IC₅₀ = 0.49–0.61 mg mL^?1) showed higher inhibitory activity than the water extract (IC₅₀ = 1.80–1.99 mg mL^?1). Enzyme inhibition by the extracts was reversible and of mixed type. For both extracts, the dissociation constants for binding to free enzyme were significantly smaller than those for binding to enzyme–substrate complex. Ethyl‐α‐D ‐glucopyranoside (IC₅₀ = 0.19 mg mL^?1), isolated for the first time from sea cucumber, and adenosine (IC₅₀ = 0.13 mg mL^?1), were identified as key tyrosinase inhibitors. CONCLUSION: The sea cucumber extracts were demonstrated to possess considerable inhibitory potency against the diphenolase activity of tyrosinase, suggesting that the sea cucumber may be a good source of safe and effective tyrosinase inhibitors. Copyright © 2011 Society of Chemical Industry     

Biological activities of the essential oil and methanolic extract of Micromeria fruticosa (L) Druce ssp serpyllifolia (Bieb) PH Davis plants from the eastern Anatolia region of Turkey

The in vitro antimicrobial and antioxidant activities of the essential oil and methanolic extract of Micromeria fruticosa ssp serpyllifolia as well as the composition of the essential oil were examined. The essential oil exhibited activity against 14 bacteria, three fungi and a yeast, with minimal inhibitory concentration (MIC) values ranging from 31.25 to 125 µl ml^?1, whilst the methanolic extract was inactive. Antioxidant activity was measured by two methods, namely scavenging of the free radical DPPH and inhibition of linoleic acid oxidation. The methanolic extract exhibited significant antioxidant activity in both assays, providing 50% inhibition at 70.9 ± 0.5 µg ml^?1 concentration in the DPPH assay and inhibiting linoleic acid oxidation to 59% at 2 mg ml^?1 concentration, whilst the essential oil showed activity only at higher concentrations. The gallic acid equivalent total phenolic content of the methanolic extract was found to be 55.2 ± 2.00 µg mg^?1 dry weight extract (5.5% w/w). The chemical composition of the hydrodistilled essential oil was analysed by means of GC/MS. Twenty‐nine constituents were identified, the main ones being piperitenone (50.61%) and pulegone (29.19%). Copyright © 2004 Society of Chemical Industry     

The effects of soluble gas stabilisation on the quality of packed sardine fillets (Sardina pilchardus) stored in air,VP and MAP

Sardine (Sardina pilchardus) is a species that for its abundance assumes great importance in the Portuguese fishing sector. In order to contribute for a better utilisation of this species, the aim of this study was to investigate the effect of the pre‐treatment with soluble gas stabilisation (SGS) (100% CO₂ at 2 bar, during 15 and 30 min) on the quality and shelf‐life of sardine fillets, packed in air (AP), vacuum (VP) and modified atmosphere (MAP: 5% O₂/35% CO₂/60% N₂). During the chilled storage, the quality changes were evaluated by sensory evaluation, chemical and microbiological analysis. The total volatile basic nitrogen content remained almost constant, between 16 and 19 mg N/100 g muscle, during the storage period, for all samples. The TBARs values increased with storage time, for all batches and storage conditions. The application of SGS treatment to sardine fillets, resulted in a bacteriostatic effect, contributing to the improvement of the microbiological quality of fillets. Considering a sensory criteria, the shelf‐life of SGS pre‐treated sardine fillets was found to be 5 days in AP and MAP while in VP‐treated fillets a shelf‐life of 8 days was reported. At sensory rejection, sardine fillets presented a K‐value of 30% in AP and MAP batches and 40% in VP batch.     

Fatty acid profiles, antioxidant compounds and antiradical properties of Pinus halepensis Mill. cones and seeds

BACKGROUND: Pinus halepensis (Aleppo pine) is a widespread tree that can be found in both natural and urban environments. A discrimination study based on the antioxidant compounds, antioxidant capacity and fatty acid (FA) profile of P. halepensis cones (PHC) and seeds (PHS) was performed. RESULTS: The total amount of phenols was about 72‐fold higher in PHC extract than in PHS extract (P < 0.001). Anthocyanin and carotenoid contents were 10‐ and 12‐fold higher respectively in PHC extract. PHC and PHS extracts at a concentration of 1 mg mL^?1 differed significantly in free radical‐scavenging activity on 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH^?) (86.65 vs 16.97%). PHC had higher antioxidant ability on 2,2′‐azino‐bis(3‐ethylbenzothialozine‐6‐sulfonic acid) radical cation (ABTS^?+) than PHS (EC₅₀ 0.368 vs 2.345 mg mL^?1). The FA profile of PHC oil revealed its richness in saturated FAs (41.5%) and high levels of trans FA isomers, with a predominance of trans,trans ‐linoleic acid (4.74%). However, polyunsaturated FAs in PHS oil represented more than 64% of total FAs. CONCLUSION: PHC showed important antioxidant activities as well as high levels of bioactive compounds. Thus PHC is a potential source of natural antioxidants that may afford several health benefits. However, the lipid extract of PHS seems to have more nutritional value as a polyunsaturated oil than that of PHC, which is high in saturated and trans FAs. Copyright © 2011 Society of Chemical Industry     

In vitro antioxidant and antiproliferative activity of three rosemary (Rosmarinus officinalis L.) extract formulations

Antioxidant and antiproliferative activities of three rosemary extract formulations (VivOX 20, VivOX 40 and Inolens 50) with different contents of carnosic acid, carnosol and methylcarnosol were tested in vitro. Electron spin resonance measurements revealed that Inolens 50 extract that contained highest amount of carnosic acid was the most potent scavenger of hydroxyl (concentration of extract where 50% of its maximal scavenging activity is observed, that is, EC₅₀, 109.54 μg mL^?1), superoxide anion (EC₅₀ = 7.94 μg mL^?1) and 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) (EC₅₀ = 27.4 μg mL^?1)‐free radicals. Comparison of the radar charts of standard antioxidants and rosemary extracts showed similarity between antioxidant characteristics of Inolens 50 and chlorogenic and caffeic acids. Tested rosemary extracts exhibited significant (P ≤ 0.01) antiproliferative effect in cervix epitheloid carcinoma (HeLa), breast adenocarcinoma (MCF7) and colon adenocarcinoma (HT‐29) cell lines. In both MCF7 and HeLa cell lines, the extracts yielded very low IC₅₀ values (concentration of extract needed to inhibit cell growth by 50%), the most pronounced being for Inolens 50 in MCF7 (IC₅₀ = 9.95 μg mL^?1) and VivOX 20 in HeLa cell line (IC₅₀ = 10.02 μg mL^?1). The obtained results may provide support for the use of tested rosemary extracts as nutraceuticals and phytopharmaceuticals.     

Determination of reaction kinetics of hydrolysis of tilapia (Oreochromis niloticus) protein for manipulating production of bioactive peptides with antioxidant activity,angiotensin‐I‐converting enzyme inhibitory activity and Ca‐binding properties

To manipulate enzymatic hydrolysis of tilapia (Oreochromis niloticus) muscle protein for production of bioactive peptides, its reaction kinetics was intensively studied. The study showed that the production of peptides with different bioactive properties including antioxidant activity, angiotensin‐I‐converting enzyme (ACE) inhibition and Ca‐binding property and their kinetics were affected by the degree of hydrolysis and substrate concentration. A comparative study on reaction kinetics found that the kinetic parameters for the production of each bioactive peptide are unique, that is, the maximum initial velocity, V_max, for hydrolysis of protein was as high as 1.07 mg mL^?1 min^?1, but that for the production of peptides with antioxidant activity and Ca‐binding property were very low, range of 7.14–66.7 μg mL^?1 min^?1, and that for the production of peptides with ACE inhibitory activity was the lowest, at 2.57 μg mL^?1 min^?1. This knowledge of reaction kinetics of protein hydrolysis would be useful for manipulating and optimising the production of peptides with desired bioactive properties.     

Nutritional composition and sensory attributes of Alaskan flatfishes compared to plaice (Pleuronectes platessa)

Proximate composition, fatty acids profiles and other nutritional values were evaluated for fillets of Limanda aspera (yellowfin sole), Lepidopsetta bilineata (southern rock sole) and Lepidopsetta polyxystra (northern rock sole) and compared to North Sea plaice (Pleuronectes platessa). Additional information is given on the composition of fillets from arrowtooth flounder (Atheresthes stomias). Plaice (0.8% lipid) and Alaska soles (1.0–1.2% lipid) can be classified as lean species, resulting in low 0.3–0.5 g ∑EPA+DHA/100 g muscle, although the fatty acid profiles of the extracted lipids were characterised by high amount of n‐3 fatty acids (33.2–47.3%). Arrowtooth flounder belong to the medium‐fat species (4.3%). Taurine was the most prevalent free amino acid; mean values ranging between 221 mg100 g^?1 and 247 mg100 g^?1 wet weight. The selenium content varied between 130 and 310 μg kg^?1 ww. Sensory attributes of Southern and Northern rock sole were comparable to plaice.     

Chemical composition,antioxidant activity and anti‐lipase activity of Origanum vulgare and Lippia turbinata essential oils

This study reported the chemical composition, phenolic content, antioxidant and anti‐lipase activity of oregano and Lippia essential oils. The major compounds found in oregano essential oil were γ‐terpinene (32.10%), α‐terpinene (15.10%), p‐cymene (8.00%) and thymol (8.00%). In Lippia essential oil, α‐limonene (76.80%) and 1,8‐cineole (4.95%) represented the major compounds. Oregano essential oil had higher phenolic content (12.47 mg gallic acid mL^?1) and DPPH scavenging activity (IC₅₀ 0.357 μg mL^?1) than Lippia essential oil (7.94 mg gallic acid mL^?1 and IC₅₀ 0.400 μg mL^?1, respectively). Both essential oils had similar antioxidant indexes (about 1.2) determined by Rancimat. Moreover, oregano essential oil had also higher anti‐lipase activity (IC₅₀ 5.09 and 7.26 μg mL^?1). Higher phenolic content in the essential oils was related with higher scavenging and anti‐lipase activities. Oregano and Lippia essential oils could be used as natural antioxidants on food products.     

Moringa oleiferia leaves extract: a natural antioxidant for retarding lipid peroxidation in cooked goat meat patties

The effective utilisation of Moringa oleiferia mature leaves (MOL) extract as an antioxidant in cooked goat meat patties during refrigerated storage was investigated, and its efficiency was evaluated against butylated hydroxytoluene (BHT). The extract exhibited high phenolic content (48.36 mg of gallic acid equivalent per g), flavonoid (31.42 mg g^?1 of sample) being the major component. Moringa oleiferia mature leaves extract showed excellent antioxidant activity as determined by radical‐scavenging activity of 1, 1‐diphenyl 2 picrylhydrazyl (DPPH). The IC₅₀ value of MOL extract for 2, 2‐diphenyl‐1‐picrylhydrazyl radical scavenging was 18.54 μg mL^?1. Total phenolic content (as gallic acid equivalent) significantly (P < 0.05) increased from 285.56 in control to 379.45 in patties with MOL extract. MOL extract (0.1%) when added to meat was found to retard lipid peroxidation of cooked goat meat patties as measured by TBARS number during refrigerated storage. The increase in TBARS number in MOL extract–treated samples was very slow and remained lowest (0.53 mg malonaldehyde per kg sample) up to 15 days. The antioxidant activity of MOL extract was found to be comparable to BHT. Addition of MOL extract did not affect any of the sensory attributes of patties. The MOL extract at a level of 100 mg/100 g meat was sufficient to protect goat meat patties against oxidative rancidity for periods longer than the most commonly used synthetic antioxidant like BHT.     

Inhibition effects of green tea and grape seed extracts on lipid oxidation in bonito fillets during frozen storage

The aim of this study was to investigate inhibition effects of green tea and grape seed extracts on lipid oxidation in bonito (Sarda sarda) fillets during frozen storage. Dried and powdered green tea and grape seed were extracted using ethanol. Extract solutions of 1 g 100 g^?1 were prepared using concentrated extracts and distilled water. Bonito fillets were divided into two groups. The first group was dipped into extract solutions and then frozen. The second group of fillets was glazed by extract solutions. Oxidation increased progressively through the storage period. 2‐Thiobarbituric acid and para‐anisidine values of samples treated with green tea and grape seed extracts remained at low levels. Both plant extracts displayed successful effects in delaying lipid oxidation compared to the control groups. The best results were obtained by extract treatment of fillets before freezing.     

Quality evaluation of Korean soy sauce fermented in Korean earthenware (Onggi) with different glazes

The aim of this study was to investigate the effect of porosity‐controlled earthenware as fermentation vessels for Korean soy sauce. Porosity of fermentation vessels was controlled by glazing the surfaces of Korean earthenware. Three kinds of onggis– the outside glazed, inside and outside glazed, and unglazed onggi – were made and used to investigate the effect of glazing on the fermentation of soy sauce. During fermentation of soy sauce in porosity‐controlled earthenwares at 30 °C for 4 months, physical, chemical, microbiological and sensory quality attributes were monitored. Compared to other vessels, soy sauce fermented in onggi with both inside and outside surfaces glazed showed less water loss (10.7%), salt content (17.6%) and pH (pH4.4) after the fourth month. It also produced higher total acidity (1.43%), protease activity (810 μg mL^?1 min^?1) and microbiological changes that included total aerobic bacteria [4.3 log(cfu mL^?1)], lactic acid bacteria [3.8 log(cfu mL^?1)] and yeast [4.2 log(cfu mL^?1)]. The contents of total nucleotide (200–255 mg per 100 g sample) and free amino acids (4634–4848 mg per 100 g sample) in soy sauce were not consistent with glazing, which may be more affected by other factors, such as water loss, than the porosity of vessels. However, the percentage of glutamic acid among total free amino acids was 23.6% in onggi with both surfaces glazed, which was a little higher than the 21.9% in the outside glazed and 21.5% in the unglazed. These positive physicochemical and microbiological changes during fermentation in onggi with both sides glazed also resulted in higher sensory quality.     

Effect of solvent type on the extractability of bioactive compounds,antioxidant capacity and colour properties of natural annatto extracts

This study was conducted to obtain annatto extracts with both high antioxidant capacity and colour potential using solvents of different polarities (water, ethanol/water, ethanol, ethanol/ethyl acetate and ethyl acetate). The highest levels of total phenolic compounds were found in the water, ethanol/water and ethanol extracts (0.5 mg GAE mL^?1), and the highest level of bixin was found in the ethanol/ethyl acetate extract (5.2 mg mL^?1), which was characterised as the reddest and the most vivid one (a* = 40.5, h° = 46.1, C* = 58.4). The ethanol/ethyl acetate extract also showed the highest antioxidant activity (4.7 μm TEAC mL^?1) and the highest percentage of tryptophan protection against singlet oxygen (63.6%). On the other hand, ethyl acetate and ethanol/water were the least effective solvents for the extraction of phenolic compounds and bixin, respectively. According to the multivariate statistical analysis, ethanol/ethyl acetate and ethyl acetate were the most promising solvents to obtain annatto extracts with both antioxidant and colour properties.     

Antifungal activity of plant extracts against Colletotrichum lagenarium, the causal agent of anthracnose in cucumber

BACKGROUND: Colletotrichum lagenarium is an important plant‐pathogenic fungus that causes anthracnose of cucumber, a disease that is widespread under both greenhouse and field cultivation. To find a promising method for the control of this disease, extracts of eight plants from China were screened in the study presented here. RESULTS: The results showed that the extract of Cinnamomum camphora (L.) Presl had significantly greater inhibitory activity against C. lagenarium than the other seven plant extracts tested in vitro. At 5 days after inoculation in a potted seedling experiment, C. camphora extract demonstrated 95% control of C. lagenarium at a concentration of 16 mg mL^?1, and the MIC₅₀ was 2.596 mg mL^?1. Microscopic observation showed that this extract had a significant impact on the morphology of the fungus, leading to shorter hyphae that were more branched; this observation was associated with the inhibition of mycelial growth. Stability assays revealed that the extract was relatively stable at 80 °C, under acidic conditions and when exposed to light and short periods of UV radiation. CONCLUSION: These results demonstrated that the extract from C. camphora could be used as a potent phytochemical fungicide. Copyright © 2012 Society of Chemical Industry     

Effects of rosemary and sage tea extracts on the sensory,chemical and microbiological changes of vacuum‐packed and refrigerated sardine (Sardina pilchardus) fillets

The effect of the natural antioxidants and antimicrobials from ethanol extracts of rosemary and sage tea on sensory, chemical [Total volatile basic nitrogen (TVB‐N), thiobarbituric acid reactive substances (TBARs), peroxide value (PV), free fatty acid (FFA)] and microbiological (total viable count‐TVC and total coliform count) changes of vacuum‐packaged sardine (Sardina pilchardus) fillets stored at 3 ± 1 °C was investigated for 20 days. The fish fillets were divided into three groups: untreated group (control, C) and treated groups that were immersed in a 1 L of distilled water containing 10 g rosemary (R group) or sage tea (S group) extracts for 4 min. The shelf life of sardine fillets was found to be 13 days for control (C), 20 days for R and S groups according to sensory assessment results, whose corresponded microbiological assessment showed a shorter shelf life (5 days for C group, 9 for R and S groups). At the end of storage period, TBARs values were 0.98 mg malonaldehyde kg^?1 for C group, 0.66 malonaldehyde kg^?1 for R group and 1.44 mg malonaldehyde kg^?1 for S group. Microbiological results showed that natural compounds from rosemary and sage tea resulted in a lower bacterial growth in fish fillets during the storage period.     

Influence of degree of hydrolysis on functional properties and angiotensin I‐converting enzyme‐inhibitory activity of protein hydrolysates from cuttlefish (Sepia officinalis) by‐products

BACKGROUND: In Tunisia the cuttlefish‐processing industry generates large amounts of solid wastes. These wastes, which may represent 35% of the original material and constitute an important source of proteins, are discarded without any attempt at recovery. This paper describes some functional properties and the angiotensin I‐converting enzyme (ACE)‐inhibitory activity of protein hydrolysates prepared by hydrolysis of cuttlefish (Sepia officinalis) by‐products with crude enzyme extract from Bacillus licheniformis NH1. RESULTS: Cuttlefish by‐product protein hydrolysates (CPHs) with different degrees of hydrolysis (DH 5, 10 and 13.5%) were prepared. All CPHs contained 750–790 g kg^?1 proteins. Solubility, emulsifying capacity and water‐holding capacity increased while fat absorption and foaming capacity decreased with increasing DH. All hydrolysates showed greater fat absorption than the water‐soluble fraction from undigested cuttlefish by‐product proteins and casein. CPHs were also analysed for their ACE‐inhibitory activity. CPH3 (DH 13.5%) displayed the highest ACE inhibition (79%), with an IC₅₀ value of 1 mg mL^?1. CONCLUSION: Hydrolysis of cuttlefish by‐product proteins with alkaline proteases from B. licheniformis resulted in a product with excellent solubility over a wide pH range and high ACE‐inhibitory activity. This study suggests that CPHs could be utilised to develop functional foods for prevention of hypertension. Copyright © 2010 Society of Chemical Industry     

Antioxidant activity of bigeye tuna (Thunnus obesus) head protein hydrolysate prepared with Alcalase

The antioxidant activities of tuna head protein hydrolysate (THPH) prepared with Alcalase were evaluated. THPH showed evident radical scavenging activity in a dose‐dependent manner with the IC₅₀ values for 1,1‐diphenyl‐2‐pycrylhydrazyl (DPPH), superoxide and hydroxyl radicals being 1.34, 1.20 and 2.84 mg mL^?1, respectively, and its reducing power was 0.948 at 12.5 mg mL^?1. THPH showed good inhibitory activity in soybean oil peroxidation after accelerated oxidation at 60 °C, and the oils with 0.01%, 0.05% and 0.1% THPH had significantly (P < 0.05) lower peroxide values than the control, after storage at 60 °C. Moreover, the inhibited oxidation effect of 0.1% THPH was similar to that of 0.01% butylated hydroxytoluene (BHT). The molecular weight distribution of THPH revealed that 70.5% of the total amount was peptides with molecular weight lower than 5000 Da, composing mostly of low molecular weight peptides located at 1020–2585 Da (30.78%) and 241–1020 Da (37.15%).