Effect of legume seed extracts on the inhibition of proteolytic activity and muscle degradation of fresh water prawn (Macrobrachiumrosenbergii)

Trypsin inhibitors in the extracts from soybean (Glycine max), adzuki bean (Vigna angularis), bambara groundnut (Vigna subterranea) and red kidney bean (Phaseoulus vulgaris) varied in amount and molecular weight. The soybean extract had the highest level of trypsin inhibitor with molecular weight (MW) of 21 kDa, followed by bambara groundnut extract possessing trypsin inhibitor with MW of 15 kDa. Both extracts showed a more effective inhibition towards crude protease extract (CE) from the hepatopancreas of fresh water prawn (Macrobrachium rosenbergii) than the extracts from adzuki and red kidney beans. Activity staining also reconfirmed the higher inhibitory activity on CE from hepatopancreas by the extracts from both soybean and bambara groundnut. The extracts from all seeds were able to inhibit the degradation of fresh water prawn meat containing CE in a concentration dependent manner. Based on inhibitor study, the extracts from soybean and bambara groundnut can be a potential aid to suppress the muscle softening of fresh water prawn, mediated by trypsin-like proteases released from hepatopancreas, during extended iced storage.     

Collagenolytic serine protease in fresh water prawn (Macrobrachiumrosenbergii): Characteristics and its impact on muscle during iced storage

Proteolytic activity of crude protease extract (CPE) from the hepatopancreas of fresh water prawn (Macrobrachium rosenbergii) was studied. Optimal activity of CPE was found at pH 7 and 60 °C when casein was used as a substrate. The activity was strongly inhibited by 10 mM N-ρ-tosyl-L-lysine chloromethylketone (TLCK), suggesting that trypsin-like protease was dominant. CPE also showed the collagenolytic activity toward pepsin soluble collagen extracted from prawn muscle. During extended iced storage of 4 days, proteolytic and trypsin activities were found in the first segment of prawn abdomen. These activities were detected in the second segment after 4 days of storage. Heat soluble collagen content was continuously increased during the storage. Nevertheless, no changes in proteolytic activity and heat soluble collagen content were obtained in the abdomen of prawn with the removal of hepatopancreas. Therefore, the release of trypsin-like collagenase from hepatopancreas was most likely responsible for the softening of prawn meat during iced storage.     

Post-mortem changes of muscle from fresh water prawn (Macrobrachium rosenbergii) as influenced by spawning stages

Post-mortem changes of the muscle from pre- and post-spawned fresh water prawn (Macrobrachium rosenbergii) were comparatively monitored during 7 days of iced storage. During the storage, the muscle of pre-spawned prawn had a greater value of trichloroacetic acid (TCA) soluble peptide, heat soluble collagen and pepsin-soluble collagen (PSC) contents than did post-spawned counterpart. Those components in the muscle of both prawns increased markedly after 3 days of storage (p < 0.05). Conversely, insoluble collagen (ISC) content, shear force value and texture liking of both prawns decreased (p < 0.05), indicating the softening of muscle. No changes in protein patterns were observed, except the decreased band intensity of 66 kDa protein in water soluble fraction of both prawns was found after 3 days of storage. T_max and enthalpy of PSC from both prawns decreased during the first 4 days of storage (p < 0.05), suggesting the degradation or denaturation of collagen in the muscle. Light microscopic study showed the lowering of intercellular connection of raw meat and higher gaping in cooked meat when the samples were stored for a longer time. Therefore, post-mortem characteristics of prawn muscle was affected by storage time and spawning stages.     

COOKING CHARACTERISTICS OF FOUR CULTIVARS OF BAMBARA GROUNDNUTS SEEDS AND STARCH ISOLATE

The proximate composition and textural changes during the cooking of four bambara groundnut (Voandzeia subterranea) seed cultivars were evaluated. Bambara groundnut seeds contained 18–21% protein 6–8% fat, 8–10% moisture and 1.2–2.6% ash. Changes in hardness in relation to cooking time was monitored for 2 h. The cooking time for softening was shorter for the cream and brown colored cultivars than for the red black colored cultivars. The swelling and viscosity properties of starch isolates prepared form the seeds were studied. There were no varietal differences (p≤0.05) in starch viscosity and swelling properties among cultivars. Estimation of tannin content of bambara groundnut seeds showed that tannin contents of the red and black seed cultivars (0.96% and 1.1%, respectively) were significantly higher (p≤0.05) than the tannin contents of cream and brown seed cultivars (0.68% and 0.72%, respectively).     

The effectiveness of six vegetable oils as protectants of cowpeas and bambara groundnuts against infestation by Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

Traditionally extracted neem kernel oil, karité oil, groundnut oil, palm kernel oil, palm oil and industrially extracted groundnut oil were assessed as protectants of cowpeas and bambara groundnuts against Callosobruchus maculatus (F.). On cowpea, only neem kernel oil reduced oviposition at a treatment of 8 ml oil/kg seed. On bambara groundnut, neem kernel oil, palm oil and groundnut oil (industrially extracted) reduced oviposition at 3 ml oil/kg seed, while karité oil was effective at 5 ml oil/kg seed. With oil treatment, the degree of ovicidal activity was higher on bambara groundnuts than on cowpeas. Only neem oil also showed larvicidal properties. Even after 90 days storage, a major part of the toxic activity was retained by the cowpea testa. Neem oil at 8 ml oil/kg cowpea seed gave good protection up to 3 months, while 5 ml oil/kg bambara groundnut protected up to 6 months.     

Endogenous proteases in giant freshwater prawn (Macrobrachium rosenbergii): changes and its impacts on texture deterioration during frozen storage

Effects of endogenous enzymes on texture deterioration of Macrobrachium rosenbergii during frozen storage (−18 °C) were investigated. The prawn was pretreated with iodoacetic acid (IAA) solution to inhibit cysteine proteases and/or phenylmethylsulfonyl fluoride (PMSF) solution to inhibit trypsin before frozen storage, and sterile distilled water was used as the control. After 16 weeks of cryopreservation, the shear force of the groups treated with enzyme inhibitors was significantly higher than that of sterile distilled water-treated group (control; P < 0.05), while significantly fewer TCA-dissolved peptides, α-amino nitrogen and Myofibril fragmentation index (MFI) value were observed in all inhibitor-treated groups (P < 0.05). Compared with PMSF treatment, IAA or IAA + PMSF treatment effectively alleviated softening and remarkably reduced the accumulation of TCA-soluble peptides and AAN (α-amino nitrogen) during frozen storage, with a lower MFI value and a higher sodium dodecyl sulphate-polyacrylamide gel electrophoresis band intensity. Therefore, endogenous cysteine proteases in muscle play a crucial part in texture deterioration of giant freshwater prawn during cryopreservation.     

Collagenase activity and protein hydrolysis as related to spoilage of iced cod (Gadus morhua)

Collagenase activity and changes in muscular protein of iced Atlantic cod stored for 9 days were studied. The crude fish muscle extract showed maximum collagenase-like activity against bovine insoluble tendon collagen at 48 h of incubation at 37 °C. Collagenase activity against synthetic substrate increased (P<0.05), especially for fish in initial and advanced stages of decomposition. These results suggest that endogenous collagenases and other proteases may be responsible for the destruction of fine collagenous fibrils in the skeletal muscle of cod. The content of titin 1 decreased when decomposition was advanced. Moreover, a progressive degradation of sarcoplasmic proteins with a molecular weight of 100, 94, 85 and 80 kDa was observed. Results suggest that softening of cod muscle during iced storage is caused more by collagenase activity than by proteolysis of myofibrils.     

Factors Controlling the Deterioration of the Spiny Dogfish Squalus acanthias, during iced storage

The effects of gutting, bleeding, and delay of chilling on the deterioration of the quality of dogfish during iced storage were investigated. The rapid chilling of dogfish prevented the formation of ammonia and trimethylamine in the muscle for at least 12 days; however, the deterioration of flavor, texture, and autolytic changes tended to limit iced storage time to 8–10 days. The changes in muscle lipids presented no serious problem during this period of iced storage. Gutting retarded the sensory changes and bleeding was effective in decreasing the occurrence of blood staining of the subcutaneous muscle.     

Studies on the nutritive characteristics and fracture resistance to compressive loading of selected bambara groundnut lines

Extensive laboratory experiments were conducted to determine the nutritive characteristics and fracture resistance to compressive loading of some bambara groundnut lines. Data obtained showed percentage carbohydrate, protein and oil contents of 52.60, 17.52 and 6.66 respectively for dehulled bambara groundnut seeds as against lower percentage values of 48.60, 16.99 and 6.20 obtained from the analysis of whole seeds of BgB-Br. Investigations on the mechanical properties revealed that the force needed to rupture the seeds was influenced by moisture content and loading position of the seeds. The force was found to decrease from 262 to 100 N with increase in moisture content, while the deformation increased from 1.9 to 4.5 mm with increase in moisture content. Maximum toughness occurred at different moistures which represent the moisture levels for absorbing compressive energy which are important for resisting mechanical damage during handling of the bambara groundnut lines. © 1999 Society of Chemical Industry     

Quality of rainbow trout chilled-stored after post-catch holding

The shelf-life of headed and gutted rainbow trout (Salmo gairdneri) was evaluated over period of storage at 0°C. There were three groups of samples: (i) fish held at 10°C for 6h and iced, (ii) fish held at 20°C for 6h and iced and (iii) fish held at 30°C for 6h and iced. Quality was assessed over the period of iced storage by measurements of total volatile bases (TVB), hypoxanthine, thiobarbituric acid, pH, water holding capacity (WHC) and tissue compressibility (TC). The results indicated that holding at various time/temperature periods before icing influences quality over the period of iced storage. Deterioration in quality was most pronounced when the fish had been held at high ambient temperatures of 30°C. Hypoxanthine values appeared to give an accurate indication of quality of freshwater fish. There was a linear increase in hypoxanthine values over the period of iced storage for all samples. However, for trout held at 30°C for 6 h before icing the values appeared to be highest. The coefficients of linear regression for fish iced immediately on receipt were lowest per day. It is suggested that hypoxanthine values may be used as chemical indicators of quality of freshwater trout.     

Susceptibility of unprotected seeds and seeds of local bambara groundnut cultivars protected with insecticidal essential oils to infestation by Callosobruchus maculatus (F.) (Coleoptera: Bruchidae)

Ten local cultivars of bambara groundnut, Vigna subterranea (L.) Verdcourt obtained directly from farmers in Potiskum, Nigeria and from the Institute for Agricultural Research, Samaru, Nigeria were compared with three improved varieties developed at the International Institute of Tropical Agriculture, Ibadan, Nigeria for their susceptibility to infestation by Callosobruchus maculatus (F.). Three cultivars (Maifarinhaneh, Angale and Bunmonu) with a susceptibility index (SI) of 3.06-3.71 were identified as slightly susceptible to C. maculatus; four cultivars (Bagantere, Bakingangala, Ole and Bakiyawa 1) and one improved variety (TVSU 1061) with an SI of 4.39-4.93 as moderately susceptible; and three cultivars (Bidi, Uzu and Dadinkowa 1) and two improved varieties (TVSU 702 and TVSU 751) with an SI of 5.00-5.34 as susceptible. Five of the cultivars were used to examine the ability of beetle populations to overcome varietal resistance over six successive generations. Development time was significantly longer but percentage of adults that emerged and susceptibility of bambara groundnuts were significantly lower in F(4), F(5) or F(6) generations than in the F(1) or F(2) generation. The efficacy of combining insecticidal essential oils obtained from clove, Syzgium aromaticum, West African black pepper (WABP), Piper guineense, and ginger, Zingiber officinale applied at the rate of 2 mg/20 g seed and six of the local bambara groundnut cultivars (Angale, Maifarinhaneh, Bakingangala, Bagantere, Bunmonu and Bidi) with differing susceptibilities to C. maculatus (F.) was also assessed during a 3-month storage period. The three essential oils significantly reduced the percentage of C. maculatus adults that emerged from the bambara groundnut cultivars in the F(1) generation and the number of adult offspring that developed in the cultivars during the 3-month storage period. The mean number of progeny that developed in untreated seeds and seeds treated with clove, WABP and ginger oils during the study period were 73.0, 0.0, 0.1 and 0.2, respectively. No adult C. maculatus, however, developed in slightly and moderately susceptible cultivars treated with essential oils. Treatment of seeds of Bidi (a susceptible cultivar) with the essential oils reduced the percentage of adults that emerged in the F(1) generation from 26.8% in untreated seeds to 0.0, 0.1 and 0.4% in seeds treated with clove, WABP and ginger oils, respectively; and reduced loss in seed weight after three months' storage from 34% to 0.0, 0.01 and 0.1%, respectively.     

In-vitro multienzyme digestibility of protein of some plant source flours blended with bovine plasma protein concentrate

The in-vitro multienzyme protein digestibilities of the flours of maize, cassava, pigeon pea (Cajanus cajan), African yambean (Sphenostylis stenocarpa) and bambara groundnut (Vigna subterranea), blended with bovine plasma protein concentrate were investigated. The multienzyme system consists of trypsin, chymotrypsin and peptidase. It was found that the addition of bovine plasma protein concentrate improved the protein digestibility of the flours compared with flours without the additive. The digestibilities were increased by between 3% in bambara groundnut blended flour to about 10% in cassava blended flour. When the flours were wet-heat treated, the digestibilities further increased in all samples with increments between 7·5 % in bambara groundnut and 16·6% in cassava flour. Bovine plasma protein concentrate may be a good source of protein for the fortification of protein-deficient foods, particularly maize and cassava flours.     

Characterisation of proteolytic enzymes from muscle and hepatopancreas of fresh water prawn (Macrobrachium rosenbergii)

BACKGROUND: Fresh water prawn in Thailand is widely consumed due to its delicacy. During postmortem handling and storage, prawn meat becomes soft and mushy, probably as a result of indigenous proteases. Therefore, an understanding of prawn proteases associated with the degradation of muscle proteins from fresh water prawn could pave the way for prevention of such a phenomenon during extended storage. RESULTS: Proteolytic enzymes in the crude extract (CE) from muscle and hepatopancreas of fresh water prawn (Macrobrachium rosenbergii) were characterised. CE from muscle exhibited the highest hydrolytic activities towards haemoglobin at pH 5 and 50 °C, while that from hepatopancreas had the highest activity on casein at pH 7 and 60 °C. Based on inhibitor study, cysteine protease and serine protease were dominant in CE from muscle and hepatopancreas, respectively. CE from muscle rarely hydrolysed natural actomyosin (NAM), but could not degrade pepsin‐soluble collagen (PSC). Conversely, NAM and PSC were susceptible to hydrolysis by CE from hepatopancreas as evidenced by the marked decreases in band intensity. Activity staining using haemoglobin, casein and gelatin as substrates revealed that no proteolytic or gelatinolytic activity was observed in CE from prawn muscle, while CE from hepatopancreas exhibited pronounced hydrolytic activities towards all substrates. CE from muscle showed calpain and cathepsin L activities but CE from hepatopancreas mainly exhibited tryptic and chymotryptic activities. CONCLUSION: Serine proteases, mainly trypsin‐like or chymotrypsin‐like, from hepatopancreas were probably responsible for the softening of prawn meat during postmortem storage via the degradation of both muscle and connective tissues. Copyright © 2010 Society of Chemical Industry     

Broccoli Storage: Effect of N6-benzyladenine, Packaging, and Icing on Color of Fresh Broccoli

Broccoli plants and heads were treated with N⁶-benzyladenine (BA) as either a preharvest spray (25 or 50 ppm) or a postharvest dip (25 or 50 ppm) with 0.1% Tween 20. BA-treated and untreated samples were stored at 0–l°C for 10 wk using one of three storage methods - control, icing, or packaging. Subjective color evaluation was the most sensitive measure of color changes during storage. Chlorophyll concentration was a better objective measurement of color changes than instrumental color values. Acceptable broccoli color was noted in iced and packaged samples at 10 wk of storage. Preharvest treatment with BA (25 ppm) resulted in the best color retention in iced and packed samples. Use of a yellowing-resistant variety and storage treatments (icing and packaging) were the most important factors in improved shelf-life.     

In situ sample cleanup during immunoassay: a simple method for rapid detection of aflatoxin B, in food samples

A strategy for rapid in situ elimination of interfering substances that are present in extracts of food samples during assay is described in this article. The novel feature of this method is that the sample purification is carried out as a part of the assay, and a separate sample cleanup step is not required. The assay procedure involves the sequential addition of standard or sample, cleaning solutions, and aflatoxin B1-horseradish peroxidase conjugate (AFB1-HRP) over antibody-spotted zones of a membrane, and 3,3'-diaminobenzidine was used as the substrate for visualization. We have determined that trifluoroacetic acid and propionic acids at concentrations of 100 mM are highly effective for cleaning groundnut, wheat, corn, and poultry feed samples and that NaHCO3 (100 mM) is successful in cleaning processed soybean. In all cases, subsequent washing was performed with phosphate-buffered saline solution to facilitate the removal of traces of adhering interfering substances. A batch of 12 samples can be analyzed within 8 min either by visual comparison of the color intensity (inversely related to the analyte concentration) of a sample spot with those of reference standards or, more precisely, by densitometry. The method was tested for the analysis of AFB1 in groundnut, wheat, corn, processed soybean, chili, and poultry feed. The detection limit obtained was 5 microg/kg, except for chili, where it was 10 microg/kg. The average recoveries from different noninfected food samples spiked with AFB1 at concentrations of 5 to 100 microg/kg were between 99 and 105%. The values obtained for infected corn and groundnut samples correlated well with the estimates obtained by high-pressure liquid chromatography. The absence of a sample extraction step reduces the cost and labor involved in the assay. The method may be potentially applicable to the assay of other mycotoxins and environmental pollutants.     

Partial Characterization of a Collagenolytic Enzyme Fraction From the Hepatopancreas of the Freshwater Prawn, Macrobrachium rosenbergii

Textural changes of freshwater prawn during ice-chilled/refrigerated storage are believed in part to be due to an autolytic process. A collagenolytic enzyme fraction, isolated from the hepatopancreas of the freshwater prawn, was most active at 37°C and pH 6.5-7.5 and was also active at 0°C. The addition of this enzyme fraction to prawn tissue increased the hydrolysis of prawn collagen at 0°C for 96 hr indicating that this enzyme fraction might be responsible for the textural change in prawn during ice-chilled storage.     

Effect of chitosan edible coating on the quality of double filleted Indian oil sardine (Sardinella longiceps) during chilled storage

The effectiveness of edible chitosan coating (1 and 2%) on the quality changes of Indian oil sardine (Sardinella longiceps) in iced condition was assessed. The chitosan prepared in the study had higher degree of deacetylation (83%). Edible coating with chitosan was effective in inhibiting bacterial growth and reduced the formation of volatile bases and oxidation products significantly. The muscle pH increased with the storage period for all the samples. On the day of sensory rejection for untreated samples, the formation of total volatile base nitrogen and trimethylamine nitrogen was less by 14.9 and 26.1% for 1% chitosan treated sardine and 32.7 and 49% for 2% chitosan treated samples respectively. The chitosan coating improved the water holding capacity, drip loss and textural properties significantly compared to untreated sample. The eating quality was maintained up to ∼8 and 10 days for 1 and 2% chitosan treated sardine respectively, compared to only 5 days for untreated samples.     

The use of a tea polyphenol dip to extend the shelf life of silver carp (Hypophthalmicthys molitrix) during storage in ice

The effects of a tea polyphenols (TP) dip treatment on quality changes of silver carp (Hypophthalmicthys molitrix) during iced storage were examined over a period of 35 days. TP (0.2%, w/v) solution was used for the dip treatment. The control and the treated fish samples were analysed periodically for microbiological (total viable count), chemical (pH, TVB-N, TBA, K-value), and sensory characteristics. The results indicated that the effect of the TP dip treatment on the fish samples was to enable the good quality characteristics to be retained for longer and to extend the shelf life during the iced storage.     

Physicochemical Changes in Pacific Whiting Muscle Proteins during Iced Storage

No changes in actomyosin Ca²⁺-, Mg²⁺-, or Mg²⁺-Ca²⁺-ATPase activities were observed during iced storage of Pacific whiting fillets, but Mg²⁺-EGTA-ATPase increased with a loss of Ca²⁺-sensitivity. Surface hydrophobicity of actomyosin increased substantially within 2 days, but not total sulfhydryl (SH) content. During longer storage, the SH content decreased gradually, but surface hydrophobicity remained constant. Autolytic degradation products increased in fish muscle with storage time. Myosin heavy chain (MHC) was degraded by 45% within 8 days, but no noticeable difference was observed in actin. Results indicated that autolysis may be the main cause of physicochemical changes in Pacific whiting muscle proteins during iced storage.     

Optimisation of bambara groundnut water extract and skim milk composition as cryoprotectant for increasing cell viability of Lactobacillus spp. using response surface methodology

Four legume water extracts, that is bambara groundnut, soya bean, red kidney bean and black bean as well as skim milk, were examined for their effectiveness in protecting Lactobacillus rhamnosus GG and Lactobacillus fermentum SK5 during the freeze‐drying and storage. Bambara groundnut water extract (BGWE) showed promising cryoprotective activity that was comparable to skim milk. BGWE and skim milk at 2–10% w/v and 5–20% w/v individually produced survival rates for both strains of 87–88%. To further optimise the synergistic cryoprotective medium, response surface methodology was employed. The optimal combination was 4.93% w/v BGWE and 11.68% w/v skim milk for L. rhamnosus GG and 5.17% w/v BGWE and 11.36% w/v skim milk for L. fermentum SK5 with survival rates of 95.17% and 94.36%, respectively. The storage life of freeze‐dried cells of both probiotics at 4 °C and 30 °C for 6 months was markedly improved when they were produced with these optimal combinations.