The physico-chemical properties of spray-dried pitaya peel powders kept at accelerated (45 ± 2°C) and room temperature (28 ± 2°C) for 14 weeks and 6 months, respectively were evaluated. Changes in physico-chemical properties of the peel powder were used as indicators of stability, while changes of the betacyanin pigment retention was used to calculate the shelf-life of the powder. Storage temperatures significantly (p < 0.05) affected all the studied parameters and Hunter a value had the most significant change. The pigment retention of peel powder was approximately 87% at 45°C and 89% at room temperature storage. Degradation of betacyanin pigment in the powder followed the first order reaction kinetics with the half-life (t1/2) of approximately 76 weeks at 45°C and 38 months at 28°C. The spray-dried pitaya peel powder had a solubility of 87 to 92% and low in powder hygroscopicity. The final Aw of the powder did not exceed 0.6 for both storage temperatures.
This paper reviews the structure, function and applications of collagens in food industry. Collagen is the most abundant protein in animal origin. It helps maintaining the structure of various tissues and organs. It is a modern foodstuff and widely used in food and beverage industries to improve the elasticity, consistency and stability of products. Furthermore, it also enhances the quality, nutritional and health value of the products. Collagen has been applied as protein dietary supplements, carriers, food additive, edible film and coatings. Therefore, this paper will review the functions and applications of collagen in the food and beverage industries. The structure and composition of collagen are also included.
The amino-acid composition, 2, 2-Diphenyl-1-picryhydrazyl (DPPH) radical-scavenging activity, and peptide patterns of tilapia protein hydrolysates produced by the enzymatic hydrolysis of Alcalase (AH), Flavourzyme (FH) and Protamex (PH) for 5h using pH-stat method were studied. The ratio of essential amino acids to non-essential amino acids increased after hydrolysis in all samples; however, no significant differences among them were observed. AH had a highest (P < 0.05) DPPH radical-scavenging activity, but no significant difference in the DPPH between FH and PH was observed. SDS-PAGE patterns for all the hydrolysates showed significant (P < 0.05) reduction in the number and the intensity of the bands with increasing time of hydrolysis. Flavourzyme showed the lowest rate of hydrolytic activity towards the tilapia mince.
Chili shrimp paste (CSP) is a favorite condiment in Southeast Asia. Microbial spoilage makes CSP unsuitable for consumption within several days. Thermal treatment was applied to produce microbiologically safe CSP. The effect of heating process on physicochemical and sensorial properties of CSP was studied. Heating at the optimum condition (21.6 min, 80 ˚C) has been shown effective and reliable in controlling microorganisms in CSP. Complete inactivation of peroxidase activities could not be accomplished at the optimal point, and significant reduction of the total phenolic and capsaicinoids contents was observed. Sensorial evaluation indicated that thermally processed CSP was less preferred by panelists when compared to freshly prepared samples of dry weight respectively.
Malaysia is a surplus poultry producing country with well-established commercial slaughtering and processing plants. Immense quantity of heads, feet, viscera, blood and feathers are usually discarded and not optimally utilized. Chicken heads are rich in protein, and could be a potential source of gelatin. The aim of the present work was therefore to find a simpler, faster, cheaper and greener gelatin extraction technology as compared to current available methods of gelatin extraction from poultry heads. A comparison of three different gelatin extraction methods with alkaline-acid pretreatment (E1), single acid pretreatment (E2) and single alkaline pretreatment (E3) were studied to extract gelatin from chicken heads. E1 and E2 produced gelatins of Type A, while E3 produced gelatin of Type B. High bloom gelatin (>300 g) with
The quality change of fish sausage (keropok lekor) coated in sago starch-gelatine coating with
papaya seed extract (PSE) during chill storage (7°C) was determined. During storage, pH,
thiobarbituric acid value (TBA), colour, moisture, and the total plate count were evaluated. pH
of samples significantly dropped (p < 0.05) during storage, and the highest decrease was in
control sample. The moisture content in control sample had an increasing trend while that of
samples with 5 and 7% PSE coatings significantly decreased, and only a slight change for
samples with 0% PSE coating. All samples had significant increase in their TBA values during
storage. The presence of the coating provided a positive effect on the colour of the fish sausages since no significant colour changes were observed during storage. TPC of control and
coated sausage in 0, 5, and 7% PSE exceeded the recommended microbial standard after 2, 6,
8, and 4 d of storage, respectively. Overall, coating with 5% of PSE was the most effective in
retarding the quality deterioration of the fish sausages.
Response surface methodology (RSM) was used to determine the optimum experimental conditions to extract methylmercury from fish samples for GC analysis. The influence of four variables - acid concentration (3-12 M), cysteine concentration (0.5-2% w/v), solvent volume (3-9 ml) and extraction time (10-30 min) - on recovery of methylmercury was evaluated. The detection limit for methylmercury analysis using a microelectron capture detector was 7 ng g(-1) in fish samples. The mean recovery under optimum conditions was 94%. Experimental data were adequately fitted into a second-order polynomial model with multiple regression coefficients (r(2)) of 0.977. The four variables had a significant effect (p < 0.05) on the recovery of methylmercury from a reference material (BCR-463). Optimum conditions for methylmercury extraction were found using an acid concentration of 12.2 M, cysteine concentration of 2.4%, solvent volume of 1.5 ml and extraction time of 35 min. The validation of the developed method to analyze methylmercury in fish samples exhibited good agreement with mercury content in the samples.
Cocoa-specific aroma precursors and methylpyrazines in underfermented cocoa beans obtained from fermentation induced by indigenous carboxypeptidase have been investigated. Fermentation conditions and cocoa bean components were analyzed during 0 to 3 d of fermentation. Underfermented cocoa beans were characterized as having hydrophilic peptides and free hydrophobic amino acids much higher than unfermented ones. These 2 key components of cocoa aroma precursors may be produced from the breakdown of proteins and polypeptides by endogenous carboxypeptidase during the fermentation process. The enzyme was activated during fermentation. Polypeptides of 47, 31, and 19 kDa were observed in the samples throughout the 3-d fermentation period; however, only the first 2 polypeptides were remarkably reduced during fermentation. Since the 1st day of fermentation, underfermented cocoa beans contained methylpyrazines, a dominant group of cocoa-specific aroma. This might be due to microbial activities during fermentation, observed through a decrease of pH value and an increase of temperature of cocoa beans. The concentration of tetramethylpyrazines was significantly increased during the 3 d of fermentation. This may increase the cocoa-specific flavor to the beans.
Latent polyphenol oxidase (LPPO), an enzyme responsible for the browning reaction of sago starches during processing and storage, was investigated. The enzyme was effectively extracted and partially purified from the pith using combinations of nonionic detergents. With Triton X-114 and a temperature-induced phase partitioning method, the enzyme showed a recovery of 70% and purification of 4. 1-fold. Native PAGE analysis of the partially purified LPPO revealed three activity bands when stained with catechol and two bands with pyrogallol. The molecular masses of the enzymes were estimated by SDS-PAGE to be 37, 45, and 53 kDa. The enzyme showed optimum pH values of 4.5 with 4-methylcatechol as a substrate and 7.5 with pyrogallol. The LPPO was highly reactive toward diphenols and triphenols. The activity of the enzyme was greatly enhanced in the presence of trypsin, SDS, ethanol, and linoleic acid.
Vitamin A deficiency is common in many countries where rice is the staple food. Food fortification is an important strategy to address this problem. As rice noodle is the second principal form of rice products widely consumed in Asia, rice noodles could be a potential vehicle for fortification of vitamin A. In this study, rice noodles were prepared from 0, 300, 600, 1,050, and 1,500 μg of vitamin A per 100 g of rice flour. Samples were analyzed for quality, sensory evaluation, and enhancement of vitamin A intakes. Increasing level of vitamin A fortification did not influence quality and sensory properties of the rice noodles, except for the ash content, color, and appearance of the noodles. Rice noodle that was fortified with the highest level of vitamin A was found to be the darkest in color. However, this sample received scores higher than 6 (like slightly) for appearance. Furthermore, sample fortified with the highest level of vitamin A produced rice noodles with the highest level of vitamin A retention suggesting that noodles were good vehicle for vitamin A fortification. Fortification of rice flour with 1,500 μg of vitamin A produced rice noodles with 24.88% of the RDI for vitamin A per serving and provided an effective means of enhancing vitamin A intake.
Extraction of protease from a local ginger rhizome (Zingiber officinale var. Bentong) was carried out. The effect of extraction pH (6.4, 6.8, 7.0, 7.2, 7.6, 8.0, 8.4, and 8.8) and stabilizers (0.2% ascorbic acid, 0.2% ascorbic acid and 5 mM EDTA, or 10 mM cysteine and 5 mM EDTA) on protease activity during extraction was examined. pH 7.0 potassium phosphate buffer and 10 mM cysteine in combination with 5 mM EDTA as stabilizer were found to be the most effective conditions. The extraction procedure yielded 0.73% of Bentong ginger protease (BGP) with a specific activity of 24.8±0.2 U/mg protein. Inhibitory tests with some protease inhibitors classified the enzyme as a cysteine protease. The protease showed optimum activity at 60 °C and pH 6-8, respectively. The enzyme was completely inhibited by heavy metal cations such as Cu2+, and Hg2+. SDS stimulated the activity of enzyme, while emulsifiers (Tween 80 and Tween 20) slightly reduced its activity. The kinetic analysis showed that the protease has Km and Vmax values of 0.21 mg mL-1 and 34.48 mg mL-1 min-1, respectively. The dried enzyme retained its activity for 22 months when stored at -20 °C.
To improve textural attributes of puffed corn-fish snack, the effects of 1%, 1.5%, and 2% of calcium carbonate, magnesium silicate (talc), sodium bicarbonate as well as 5% and 10% of wheat bran (as the nucleating materials) on textural attributes were studied. Sensory evaluation, bulk density, expansion ratio, maximum force, and count peaks were measured using the Kramer test. The results showed that all of the additives except bran significantly enhanced the texture. Among them, talc at 0.5% was the best to enhance the density and expansion ratio. Effects of using 0.5% talc on puffed corn-fish snack microstructure were studied using scanning electron microscopy. The average cell diameter of 109 ± 48 μm and cell numbers per square centimeter of 67.4 for talc-treated products were obtained, while for nontalc-treated extrudates, average cell diameter of 798 ± 361 μm and cell numbers per square centimeter of 13.9 were found. Incorporation of 0.5% w/w of magnesium silicate reduced (7-fold) the average cell diameter while increased (4-fold) the cell number.
Bacteria with amine oxidase activity have become a particular interest to reduce biogenic amines concentration in food products such as meat and fish sausages. However, little information is available regarding the application of these bacteria in fish sauce. Hence, our study was aimed to investigate the effect of such starter cultures in reducing biogenic amines accumulation during fish sauce fermentation. Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05 isolated from fish sauce which possess amine oxidase activity were used as starter cultures in this study. Fermentation was held for 120 days at 35 °C. The pH value increased in all samples, while salt concentration remained constant throughout fermentation. Aerobic bacteria count was significantly lower (p < 0.05) in the control than in inoculated samples as a result of starter cultures addition. However, it decreased during fermentation due to the growth inhibition by high salt concentration. Proteolytic bacterial count decreased during fermentation with no significant difference (p > 0.05) among samples. These bacteria hydrolyzed protein in anchovy to produce free amino acid precursors for amines formation by decarboxylase bacteria. The presence of biogenic amines producing bacteria in this study was considered to be indigenous from raw material or contamination during fermentation, since our cultures were negative histamine producers. Amino acid histidine, arginine, lysine and tyrosine concentration decreased at different rates during fermentation as they were converted into their respective amines. In general, biogenic amines concentration namely histamine, putrescine, cadaverine and tyramine increased throughout fermentation. However, their concentrations were markedly higher (p < 0.05) in the control (without starter cultures) as compared to the samples treated with starter cultures. Histamine concentration was reduced by 27.7% and 15.4% by Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05, respectively. Both cultures could also reduce other amines during fermentation. After 120 days of fermentation, the overall biogenic amines concentration was 15.9% and 12.5% less in samples inoculated with Staphylococcus carnosus FS19 and Bacillus amyloliquefaciens FS05, respectively, as compared to control samples. These findings emphasized that application of starter cultures with amines oxidase activity in fish sauce fermentation was found to be effective in reducing biogenic amines accumulation.
Oxalic acid was evaluated as a treatment for reducing populations of naturally occurring microorganisms on raw chicken. Raw chicken breasts were dipped in solutions of oxalic acid (0, 0.5, 1.0, 1.5, and 2.0%, wt/vol) for 10, 20, and 30 min, individually packed in oxygen-permeable polyethylene bags, and stored at 4 degrees C. Total plate counts of aerobic bacteria and populations of Pseudomonas spp. and Enterobacteriaceae on breasts were determined before treatment and after storage for 1, 3, 7, 10, and 14 days. The pH and Hunter L, a, and b values of the breast surface were measured. Total plate counts were ca. 1.5 and 4.0 log CFU/g higher on untreated chicken breasts after storage for 7 and 14 days, respectively, than on breasts treated with 0.5% oxalic acid, regardless of dip time. Differences in counts on chicken breasts treated with water and 1.0 to 2.0% of oxalic acid were greater. Populations of Pseudomonas spp. on chicken breasts treated with 0.5 to 2.0% oxalic acid and stored at 4 degrees C for 1 day were less than 2 log CFU/g (detection limit), compared with 5.14 log CFU/g on untreated breasts. Pseudomonas grew on chicken breasts treated with 0.5% oxalic acid to reach counts not exceeding 3.88 log CFU/g after storage for 14 days. Counts on untreated chicken exceeded 8.83 log CFU/g at 14 days. Treatment with oxalic acid caused similar reductions in Enterobacteriaceae counts. Kocuria rhizophila was the predominant bacterium isolated from treated chicken. Other common bacteria included Escherichia coli and Empedobacter brevis. Treatment with oxalic acid caused a slight darkening in color (decreased Hunter L value), retention of redness (increased Hunter a value), and increase in yellowness (increased Hunter b value). Oxalic acid has potential for use as a sanitizer to reduce populations of spoilage microorganisms naturally occurring on raw chicken, thereby extending chicken shelf life.
In the current study, effects of fermentation on physicochemical and functional properties of brown rice flour (BRF) were investigated. Fermentation conditions were optimized using response surface methodology to achieve moderate acidity (pH 5-6), specifically pH 5.5 of brown rice batter with time, temperature and yeast concentration as the independent variables. The results indicated that brown rice batter was well fermented to maintain pH 5.5 at optimum conditions of 32 °C for 6.26 h using 1 % yeast concentration. Fermentation at moderate acidity significantly increased the levels of protein, total ash, insoluble fiber, soluble fibre, minerals, phenolics, antioxidants, resistant starch, riboflavin, pyridoxine, nicotinic acid, γ-tocotrienol, and δ-tocotrienol. However, it reduced the contents of γ-oryzanol, γ-tocopherol, α-tocopherol, phytic acid, amylose and total starch. Foaming capacity, foaming stability, oil holding capacity, gelatinization temperatures, enthalpy and whiteness of BRF were increased after fermentation. In contrast, its swelling power, water solubility index, hot paste viscosity, breakdown, and setback significantly decreased. Microstructure of BRF was also influenced, where its starch granules released from its enclosed structure after fermentation. This investigation shows evidence that yeast fermentation modified the functionality of BRF and can be used as a functional food ingredient.
A simple and rapid Fourier transform infrared (FTIR) spectroscopic method has been developed for the quantitative determination of malondialdehyde as secondary oxidation product in a palm olein system. The FTIR method was based on a sodium chloride transmission cell and utilised a partial least square statistical approach to derive a calibration model. The frequency region combinations that gave good calibration were 2900-2800, and 1800-1600 cm-1. The precision and accuracy, in the range 0-60 mumol malondialdehyde/kg oil, were comparable to those of the modified distillation method with a coefficient of determination (r2) of 0.9891 and standard error of calibration of 1.49. The calibration was cross-validated and produced an r2 of 0.9786 and standard error of prediction of 2.136. The results showed that the FTIR method is versatile, efficient and accurate, and suitable for routine quality control analysis with the result obtainable in about 2 min from a sample of less than 2 mL.
The development of nucleic-acid-based antimicrobials such as RNA-cleaving DNAzyme (RCD), a short catalytically active nucleic acid, is a promising alternative to the current antibiotics. The current rapid spread of antimicrobial resistance (AMR) in bacteria renders some antibiotics useless against bacterial infection, thus creating the need for alternative antimicrobials such as DNAzymes. This review summarizes recent advances in the use of RCD as a diagnostic and therapeutic agent against AMR. Firstly, the recent diagnostic application of RCD for the detection of bacterial cells and the associated resistant gene(s) is discussed. The next section summarises the therapeutic application of RCD in AMR bacterial infections which includes direct targeting of the resistant genes and indirect targeting of AMR-associated genes. Finally, this review extends the discussion to challenges of utilizing RCD in real-life applications, and the potential of combining both diagnostic and therapeutic applications of RCD into a single agent as a theranostic agent.
Biogenic amines formation in Indian mackerel of tropical region was investigated during storage at ambient (25-29 °C) and ice temperature (0 °C) in relation with changes of amino acids content and amines forming bacteria. All amines increased significantly during storage at two temperatures except for spermidine and spermine. Histamine concentration of 363.5 ppm was detected after 16 h stored at ambient temperature. Aerobic plate count of fish stored at ambient temperature reached 6.98 log CFU g(-1) after 16 h, close to the upper limit (7 log CFU g(-1)) suggested by International Commission on the Microbiological Specifications for Foods (ICMSF). However, proper icing procedure retarded the formation of histamine effectively, resulting only 8.31 ppm after 16 days of ice storage. Aerobic plate count of 5.99 and 7.72 log CFU g(-1) were recorded for fish stored in ice after 16 days and ambient temperature after 20 h, respectively. Histamine exhibited high correlation with histidine (r(2) = -0.963, P 0.05). As storage time progressed, the amines forming bacteria grew significantly except for that stored in ice.
Hypertension is one of the major causes of cardiovascular-related diseases, which is highly associated with angiotensin-I-converting enzyme (ACE) activity and oxidative stress. In this study, winged bean seed (WBS), a potential source of protein, was utilised for the production of bifunctional proteolysate and biopeptides with ACE inhibitory and antioxidative properties. An enzymatic approach was applied, coupled with pretreatment of shaking and centrifuging techniques to remove endogenous ACE inhibitors prior to proteolysis. ACE inhibition reached its highest activity, 78.5%, after 12 h proteolysis while antioxidative activities, determined using assays involving DPPH˙ radical scavenging activity and metal ion-chelating activity, reached peaks of 65.0% and 65.7% at 8 h and 14 h, respectively. The said bioactivities were proposed to share some common structural requirements among peptides. A two-dimensional approach was employed for characterisation of effective peptides based on hydrophobicity, using RP-HPLC, and isoelectric property, using isoelectric focusing technique. Results revealed that acidic and basic peptides with partially higher hydrophobicity provided higher ACE inhibition activity than did neutral peptides. Finally, by using Q-TOF mass spectrometry, two peptide sequences (YPNQKV and FDIRA) with ACE inhibitory and antioxidative activities were successfully matched with a database. This study indicates that the WBS proteolysate can be a potential bifunctional food ingredient as the identified biopeptides demonstrated both ACE inhibitory and antioxidative activities in vitro.
Stichopus horrens flesh was explored as a potential source for generating peptides with angiotensin-converting enzyme (ACE) inhibitory capacity using 6 proteases, namely alcalase, flavourzyme, trypsin, papain, bromelain, and protamex. Degree of hydrolysis (DH) and peptide profiling (SDS-PAGE) of Stichopus horrens hydrolysates (SHHs) was also assessed. Alcalase hydrolysate showed the highest DH value (39.8%) followed by flavourzyme hydrolysate (32.7%). Overall, alcalase hydrolysate exhibited the highest ACE inhibitory activity (IC(50) value of 0.41 mg/mL) followed by flavourzyme hydrolysate (IC(50) value of 2.24 mg/mL), trypsin hydrolysate (IC(50) value of 2.28 mg/mL), papain hydrolysate (IC(50) value of 2.48 mg/mL), bromelain hydrolysate (IC(50) value of 4.21 mg/mL), and protamex hydrolysate (IC(50) value of 6.38 mg/mL). The SDS-PAGE results showed that alcalase hydrolysate represented a unique pattern compared to others, which yielded potent ACE inhibitory peptides with molecular weight distribution lower than 20 kDa. The evaluation of the relationship between DH and IC(50) values of alcalase and flavourzyme hydrolysates revealed that the trend between those parameters was related to the type of the protease used. We concluded that the tested SHHs would be used as a potential source of functional ACE inhibitory peptides for physiological benefits.