Palm oil is one of the most produced and traded vegetable oils in the world recently. The quality of palm oil is very important to be examined and one of the quality indices is free fatty acid (FFA) content. Thus, in this study, an electrochemical technique for the determination of FFA as alternative to conventional method (titration method) has been explored. The electrochemical method was developed based on electrochemically reduced graphene oxide (rGO) deposited onto screen printed carbon electrode (SPCE) via drop-casting technique. The modified electrode was characterized by physico-chemical and electrochemical methods, respectively. The voltammetric behaviour of 2-methyl-1,4-naphthaquinone (VK3) in the presence of palmitic acid at the modified electrode was investigated in an acetonitrile/water (3:1) mixture containing 2.5 M lithium perchlorate (LiClO4). The electrochemical detection of palmitic acid was based on the voltammetric reduction of VK3 to form corresponding hydroquinone which is proportional to the concentration of palmitic acid. Under optimum condition, the developed method showed a good linear relationship in the concentration ranging from 0.192 mM to 0.833 mM with the detection limit of 0.079 mM. The developed sensor illustrates high sensitivity and rapid detection towards determination of FFA content in palm oil.
In this work, voltammetric study based on cetyltrimethylammonium bromide (CTAB) as an ion-pairing agent for the determination of iodine level in iodized table salt has been explored. CTAB was used as an intermediate compound between iodide (I-) and the electrode due to its ability to dissociate to produce cetyltrimethylammonium ions ([CTA]+). The [CTA]+ with a long hydrophobic alkyl chain can be directly adsorbed onto the surface of the working electrode, and this in turns coated the electrode with cationic charge and enhance the electrode ability to bind to iodide (I-) and other molecular iodine ions. A mixture of iodide and CTAB ([CTA]+I-) was prepared and potential of 1.0 V for 60.0 s was applied to pre-concentrate the solution on the working electrode causing the [CTA]+I- to oxidize to iodine (I2). The produced I2 immediately react with chloride ion (Cl-) from the electrolyte of hydrochloric acid (HCl) to produce I2Cl- and form ion-pair with CTA+ as [CTA]+I2Cl-. The linear calibration curve of the developed method towards iodide was in the concentration range of 0.5-4.0 mg/L with sensitivity of - 1.383 µA mg/L-1 cm-2 (R2 = 0.9950), limit of detection (LOD) of 0.3 mg/L and limit of quantification (LOQ) of 1.0 mg/L, respectively. The proposed method indicates good agreement with the standard method for iodine determination with recovery range from 95.0 to 104.3%. The developed method provided potential application as a portable on-site iodine detector.
Volatile organic compounds (VOCs) are important to determine the aroma and sensory perception of cocoa. Starter cultures can modulate the volatile profile of cocoa beans during fermentation. This study aimed to determine the VOCs and sensory of chocolates produced using cocoa beans fermented with yeast starters (Pichia kudriavzevii (MH979681), Hanseniaspora thailandica (MH979675) and the mixture of the two yeasts (Mix)). The VOCs of chocolates were determined by Head-Space Solid Phase Microextraction followed by Gas Chromatography-Mass Spectrophotometry. Sensory analysis was determined by using trained panels. VOCs profiles of chocolates produced using beans fermented with HT, PK or Mix were noticeably different from Ghana and control chocolates (no starter). The addition of yeast starters during cocoa fermentation produced chocolates that were preferred by trained panels. Bitterness and astringency were the more intense flavour attributes in chocolates produced using cocoa beans added with yeast starters. The chocolate produced using cocoa beans fermented with PK was the most acidic; whereas chocolate produced using beans fermented with Mix had the sweetest taste. The addition of PK or HT is helpful in producing chocolate with a distinct flavour.
Guava seeds are produced as a waste product by the guava processing industry. Their high carbohydrate contents may suit the carbohydrate needs of the feed sector but their high dietary fiber content limits their feed value. The feed values of fruit seeds can be improved through germination, which involves the mobilization of nutrients through seed enzymes and alters the seed carbohydrate composition. The changes of selected carbohydrates in guava (Psidium guajava L.) seeds brought by germination to those in red bean (Vigna angularis) and winter wheat (Triticum aestivum L.) were compared. The contents of soluble carbohydrates, digestible starch, resistant starch and cellulose in the seeds were determined. The radial diffusion method was used to detect carbohydrate-degrading enzymes in the seed extracts. Guava seeds were rich in cellulose (402.2 mg/g), which decreased progressively during germination, probably through the action of cellulase. Winter wheat contained the highest starch content (412.2 mg/g) and also distinct quantities of α-amylase and cellulase. The starch contents of all the seeds decreased, but the soluble carbohydrate contents in red beans and guava seeds increased significantly by the end of germination, suggesting the transient oversupply of reserve metabolites. The content of hydrolyzed polysaccharides increased in the germinated seeds with detectable amounts of cellulose-degrading enzymes present, indicating improved value as feed. Further research is warranted to explore the potential of guava seeds as a source of low-cost animal feed supplements.
The capsicum seed core and cabbage outer leaves are common wastes generated in the vegetable processing industry. We explored the in vitro health-promoting activity of these waste products for valorization. Freeze-dried and pulverized cabbage wastes had a high bile acid binding capacity and the capsicum wastes inhibited glucose dialysis more effectively. Methanolic extracts prepared with conventional solvent extraction and ultrasound-assisted extraction were analyzed to determine their 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging capacity, in vitro α-amylase inhibitory, in vitro lipase inhibitory, and prebiotic activity. Crude extracts of cabbage and capsicum wastes were screened using GC-MS analysis. The cabbage waste extracts showed high antioxidant activities but did not inhibit α-amylase. The capsicum waste extracts inhibited both lipase and α-amylase activities and supported the growth of the probiotic bacterium, Lactobacilli brevis. Volatile compounds of the vegetables consisted mainly of phenols and fatty acid esters. In all assays except the α-amylase inhibition assay, the extracts prepared with ultrasound-assisted solvent extraction showed higher activity than those prepared using the conventional method. The capsicum seed core and cabbage outer leaves are potential sources of phytochemicals and antioxidant fibers. Capsicum waste extract supported probiotic bacterial growth without a lag phase. These waste products may be processed into high-value functional ingredients.
Developing novel fish gelatin films with better mechanical properties than mammalian gelatin is a challenging but promising endeavor. Studies were undertaken to produce fish gelatin films by combining treatments with different sugars (ribose and lactose) followed 'by' 'and' ultraviolet (UV) radiation, as possible cross-linking agents. Increase in tensile strength and percent elongation at break was recorded, which was more significant in films without sugars that were exposed to UV radiation. Films with added ribose showed decreased solubility after UV treatment and exhibited higher swelling percentage than films with added lactose, which readily dissolved in water. FTIR spectra of all the films showed identical patterns, which indicated no major changes to have occurred in the functional groups as a result of interaction between gelatin, sugars and UV irradiation. The results of this study could be explored for commercial use, depending on industrial needs for either production of edible films or for food packaging purposes.
Time and temperature parameters of superheated steam (SHS) treatment were optimised using response surface methodology (RSM) for specific lipoxygenase (LOX) activity in soya beans and crude protein content in soya milk. The optimal SHS treatment was obtained at 9.3 min and 119 °C. The predicted values of specific LOX activity and crude protein content by RSM were 0.0098 μmol/(min mg protein) and 3.2%, respectively. These values were experimentally verified to be 0.0081 ± 0.0002 μmol/(min mg protein) and 3.0 ± 0.1%, respectively. Sensory evaluation showed that the beany flavour of soya milk produced from SHS treated soya beans was significantly weaker (P
The global trend in increasing plant-based protein diets due to health and ideological reasons, has created an increased demand for food legumes that exceeds current production. To meet this demand, it is timely to reduce relying solely on soybean, and explore the potential of the underutilised legumes that are cultivated regionally. Underutilised legumes are rich in protein, carbohydrates and other nutrients that are essential for consumer. However, relatively little is known about their anti-nutritional properties and processing methods. Anti-nutritional factors (ANFs) such as enzyme inhibitors are prevalent in legumes and may interfere with digestibility and nutrient absorption. Nevertheless, an optimised food processing method will overcome this challenge and warrant a safe inclusion of legume in plant-based protein diets. Hence current study aimed to optimise the food processing methods (soaking, wet heating, autoclaving and freezing) and evaluate their efficiency in eliminating the enzyme inhibitors [trypsin, chymotrypsin (CIA) and α-amylase (AIA) inhibitors] present in seven underutilised legumes. Current study showed that autoclaving at 121 °C for 15 min reduced the AIA in all underutilised legumes tested. The AIA and CIA of bambara groundnut were successfully inactivated by wet heating at 50 °C for 60 min, and by autoclaving at 121 °C for 15 min. While the CIA of chickpea was successfully inactivated by freezing at - 80 °C for 24 h.
We evaluated the phenolic content and antioxidant capacities of pod and seed extracts (in methanol, ethanol, and water) of an underutilized legume, Clitoria fairchildiana (Howard). The antioxidant capacity of the extracts was determined using the ferric reducing antioxidant potential assay, and the free radical-scavenging capacity was evaluated using 2,2-diphenyl-1-picrylhydrazyl radical-scavenging and ABTS assays. In addition, the total flavonoids, flavonols, and tannin contents were also determined. Overall, the methanol extracts of the pod contained high concentration of phenolics and showed high antioxidant capacities compared to seed extracts. In addition, a positive correlation was found between total phenol and tannin versus antioxidant capacity. Results of the present study indicate pods and seeds of C. fairchildiana to possess rich amount of natural antioxidants, and can be further explored for their possible use as a natural additive in food or in pharmaceutical industries.
The main objective of this study was to use heating method (HM) to prepare liposome without employing any chemical solvent or detergent. Plackett-Burman design (PBD) was applied for the screening of significant process variables including the lecithin proportion, the cholesterol/lecithin ratio, the pH of solution for liposome preparation, the enzyme/lecithin ratio, the stirring time, the process temperature, the speed of stirrer, the ratio of stirrer to the tank diameter, the application of homogenization, the method of adding enzyme and centrifugation conditions on the encapsulation efficiency (EE %) of liposome and the activity of liposomal Flavourzyme (LAPU(-1)) (P
The aim of this study was to characterize chicken skin gelatin/tapioca starch composite films with varying concentrations (0-5%) of zinc oxide nanoparticles using the casting technique. The incorporation of 5% zinc oxide nanoparticles increased the water vapor permeation (1.52-1.93 × 10-7 gmm/cm2hPa) and melting temperature of the films. The tensile strength (22.96-50.43 MPa) was increased, while elongation at break decreased with increasing concentrations of zinc oxide nanoparticles. The structures of the films were also investigated via Fourier transform infrared spectroscopy. The inhibitory zones for both the gram-positive (Staphylococcus aureus) (16-20 mm) and gram-negative (Escherichia coli) (15-20 mm) bacteria were larger in the film with 5% zinc oxide. Overall, chicken skin gelatin-tapioca starch composite films with 3% zinc oxide nanoparticles were found to have the optimal formulation, demonstrating good physical, mechanical and antibacterial properties. Gelatin-based composite films with nanoparticle incorporation show strong potential for use in biodegradable food packaging materials.
Aflatoxins (AFs) are secondary metabolites produced by aflatoxigenic strains of Aspergillus flavus and A. parasiticus, the most toxic being aflatoxin B1 (AFB1). The purpose of the present work was to investigate the effects of industrial-grade packaging materials (low-density polyethylene, polypropylene, polyethylene-laminated aluminium); temperatures (25 °C, 30 °C); and water activities (0.74 a w, 0.85 a w) on AFB1 production by A. flavus and A. parasiticus in stored peanut kernels. Commercially-obtained samples were segregated into packaging materials, separately inoculated with the aflatoxigenic Aspergillus spp., and stored for 1 month under various °C + a w regimes. AFB1 production was quantified by high performance liquid chromatography with fluorescence detector (HPLC-FLD). For A. flavus in PELA, no AFB1 was detected (100% reduction) at 25 °C for both a w tested. For A. parasiticus in PELA, no AFB1 was detected at 25 °C (0.85 a w) and 30 °C (0.74 a w). Highest concentration of AFB1 was detected in LDPE for both A. flavus (46.41 ppb) and A. parasiticus (414.42 ppb), followed by PP (A. flavus 24.29 ppb; A. parasiticus 386.73 ppb). In conclusion, storing peanut kernels in PELA in a dry place at room temperature has been demonstrated as an adequate and inexpensive method in inhibiting growth of Aspergillus spp. and lowering AFB1 contamination in peanuts.
In this work, potato slices were exposed to different doses of UV-C irradiation (i.e. 2.28, 6.84, 11.41, and 13.68 kJ m(-2)) with or without pretreatment [i.e. ascorbic acid and calcium chloride (AACCl) dip] and stored at 4 ± 1 °C. Changes in enzymatic activities of polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonia lyase (PAL), as well as total phenolic content (TPC) were investigated after 0, 3, 7 and 10 days of storage. Results showed that untreated and UV-C treated potato slices at 13.68 kJ m(-2) dosage level showed significantly higher PPO, POD and PAL activities. Conversely, untreated potato slices showed the lowest TPC during storage period. Potato slices subjected to AACCl dip plus UV-C at 6.84 kJ m(-2) produced lower PPO, POD and PAL activities, as well as maintained a high TPC during storage.
The effects of flow rate, different pressures and temperatures on cocoa butter extracted from cocoa nib using supercritical carbon dioxide (scCO2) were investigated. The yield was analyzed for total fat content, triacylglycerol (TG) profile, and fatty acid (FA) profile. Extractions were carried out at pressures of 20 and 35 MPa, temperatures of 50 and 60 °C, and CO2 flow rates of 0.5, 1, 2, 4 mL min(-1). The result shows that the yield of cocoa butter extract increased with increasing pressure, temperature, and flow rate and the optimum conditions for the maximum cocoa butter extraction were 35 MPa, 60 °C and 2 mL min(-1), repectively. TGs and FAs were found to be similar in composition to those of cocoa butter obtained by conventional methods. The lower molecular weight TGs and FAs showed higher selectivity compared to higher molecular weight TGs and FAs.
Arabinoxylans (AXs) are major dietary fibre in cereals. Recently, AXs have attracted a great deal of attention because of their biological activities. These activities have been suggested to be related to the content of low molecular weight (Mw) AXs, in particular those with Mw below 32 kDa. Rice bran is a rich source of AXs. However, water extraction of AXs is difficult and often gives low yield. Extrusion processing has been used to increase the solubility of cereal dietary fibre. The aim of this research was to study the effect of extrusion screw-speeds (80 and 160) rpm on the extraction yield and Mw of water extractable AXs from rice bran. It was found that the extraction of AXs increased significantly with an increase in screw speed and was accompanied by a significant decrease in the Mw of AXs from extruded rice bran. The percentage of very low molecular weight AXs (0.79-1.58 kDa) significantly increased with increasing screw speed.
In the present study, gelatin-carboxymethyl cellulose blend film was synthesized, characterized and applied for the first time to preserve cherry tomatoes (Solanum lycopersicum var. cerasiforme) and grapes (Vitis vinifera). Gelatin (Gel) film forming solution was incorporated with carboxymethyl cellulose (CMC) at three volume per volume (Gel:CMC) ratios, namely 75:25, 50:50 and 25:75. CMC treatment has improved the transparency, tensile strength (TS), elongation at break (EAB), water vapor permeability and oxygen permeability of gelatin films. A pronounced effect was obtained for 25Gel:75CMC film. The TS and EAB values were increased from 25.98 MPa and 2.34% (100Gel:0CMC) to 37.54 MPa and 4.41% (25Gel:75CMC), respectively. A significant improvement in antimicrobial property of gelatin films against two food pathogens, namely Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was obtained in the presence of CMC. The effectiveness of gelatin-CMC blend films to extend the shelf life of agricultural products was evaluated in a 14-day preservation study. The gelatin-CMC films were successfully controlled the weight loss and browning index of the fruits up to 50.41% and 31.34%, respectively. Overall, gelatin-CMC film is an environmental friendly film for food preservation.
This study was conducted to screen the most suitable coating material for the production of microencapsulated fish oil powder using ternary blends of maltodextrin (15, 25 % w/w), Arabic gum (2.5, 7.5 % w/w), and methylcellulose (0.5, 1.5 % w/w). The physical properties of fish oil emulsion and encapsulated powders were evaluated. Arabic gum (5 % w/w) showed the most significant (p
Encapsulation has been used to overcome the problem of instability of functional pigments such as carotenoids from natural sources. In this study, β-carotene in carrot juice was spray dried with four different wall materials namely maltodextrin, resistant maltodextrin, octenyl succinate anhydride (OSA) starches Capsul (CAP) and HICAP-100 (HCAP). The objective of this research was to study the effects of various wall materials on physicochemical properties and stability of β-carotene powders along with its stability after incorporation into sugar confection. All four wall materials produced powders of acceptable quality in terms of moisture content, water activity, hygroscopicity, solubility as well as onset glass transition temperature. OSA starches exhibited better pigment retention post spray drying where juices encapsulated with HCAP showed the highest retention (94.34%). This was also represented in more orange Hue values (H°) in powders produced with CAP (53.93) and HCAP (53.33). Powders produced with HCAP also showed the longest half-life after storage at 4 °C, 25 °C, and 40 °C, as well as under exposure to light. Similarly, carrot powders produced with OSA starches also exhibited better β-carotene retention after production of hard candy confection. Though candies with HCAP encapsulated juices showed the highest β-carotene retention post candy processing, candies with CAP encapsulated carrot juices exhibited better long term stability after storage at 25 °C and 40 °C as well as under exposure to light.
Anthocyanins are considered as the largest group of water-soluble pigments found in the vacuole of plant cells, displaying range of colors from pink, orange, red, purple and blue. They belong to flavonoids, a polyphenolic subgroup. Application of anthocyanins in food systems as natural food colourants is limited due to the lack of stability under different environmental conditions such as light, pH, heat etc. Anthocyanins esterified with one or more acid groups are referred as acylated anthocyanins. Based on the presence or absence of acyl group, anthocyanins are categorized as acylated and nonacylated anthocyanins. Acylated anthocyanins are further classified as mono, di, tri, tetra acylated anthocyanins according to the number of acyl groups present in the anthocyanin. This review classifies common anthocyanin sources into non-acylated, mono-, di-, tri- and tetra-acylated anthocyanins based on the major anthocyanins present in these sources. The relative stabilities of these anthocyanins with respect to thermal, pH and photo stress in beverage systems are specifically discussed. Common anthocyanin sources such as elderberry, blackberry, and blackcurrant mainly contain nonacylated anthocyanins. Red radish, purple corn, black carrot also mainly contain mono acylated anthocyanins. Red cabbage and purple sweet potato have both mono and diacylated anthocyanins. Poly acylated anthocyanins show relatively higher stability compared with nonacylated and monoacylated anthocyanins. Several techniques such as addition of sweeteners, co-pigmentation and acylation techniques could enhance the stability of nonacylated anthocyanins. Flowers are main sources of polyacylated anthocyanins having higher stability, yet they have not been commercially exploited for their anthocyanins.
Understanding the water sorption characteristics of cereal is extremely essential for optimizing the drying process and ensuring storage stability. Water relation of rough rice was studied at 20, 30, 40 and 50 °C over relative humidity (RH.) between 0.113 and 0.976 using the gravimetric technique. The isotherms displayed the general sigmoid, Type II pattern and exhibited the phenomenon of hysteresis where it was more pronounced at lower temperatures. The sorption characteristics were temperature dependence where the sorption capacity of the paddy increased as the temperature was decreased at fixed (RH). Among the models assessed for their ability to fit the sorption data, Oswin equation was the best followed by the third order polynomial, GAB, Smith, Chung-Pfost, and Henderson models. The monolayer moisture content was higher for desorption than adsorption and tend to decrease with the increase in temperature. Given the temperature dependence of the sorption isotherms the isosteric heats of sorption were calculated using Claussius-Clapeyron equation. The net isosteric heats decreased as the moisture content was increased and heats of desorption were greater than that of adsorption.