Acetic acid buffer as extraction medium for free and bound phenolics from dried blackcurrant (Ribes nigrum L.) skins

The aim of this study was to investigate the effects of different solvent and extraction temperatures on the free and bound phenolic compounds and antioxidant activity of dried blackcurrant skins (DBS). Apart from acetic acid buffer solution, different solvent systems including water, methanol, and mixtures of methanol/water were also employed and the effects of solvent and temperature (30 °C and 50 °C) on the free and bound forms of anthocyanins, hydroxycinnamic acids and flavonols yield were assessed. The results showed that amongst all solvents, acetic acid buffer resulted in the highest free anthocyanin content (1712.3 ± 56.1 mg/100 g) (p < 0.05) after 2 h extraction at 50 °C from DBS, while lower amounts of bound anthocyanins and anthocyanidins were detected after acid hydrolysis. Acetic acid buffer extracts exhibited the highest free hydroxycinnamic acid content (268.0 ± 4.5 mg/100 g), total phenolic content (3702.2 ± 259.3 mg GAE/100 g) and DPPH activity (60.7 ± 2.0 % of inhibition). However, their free flavonol content was slightly lower (60.2 ± 0.8 mg/100 g) compared to 100% methanol at 30 °C and 50 °C, 71.4 ± 1.5 mg/100 g and 71.5 ± 6.2 mg/100 g, respectively. Two-way ANOVA indicated interactions between solvent and temperatures (p < 0.05), which suggested that the relationship between solvent and phenolic compounds depends on the extraction temperature

Stability enhancement of anthocyanins from blackcurrant (Ribes nigrum L.) pomace through intermolecular copigmentation

Intermolecular copigmentation describes the interaction between coloured anthocyanins and colourless copigment, which is not bound covalently to the anthocyanins molecule. This is the first study to investigate the effect of intermolecular copigmentation on the stability of individual anthocyanins from dried blackcurrant pomace (DBP) using four pure phenolic acids as copigments (ferulic, caffeic, chlorogenic and rosmarinic acid). Studies were performed at pH 3.0 and pH 6.0, with copigment/ anthocyanin extract molar ratio of 5:1, during storage at 20°C. At both pH 3.0 and 6.0, rosmarinic acid showed the strongest hyperchromic and bathochromic effect (p < 0.05) at day 0. However, rosmarinic acid showed low stability during storage. At pH 3.0, chlorogenic acid and control samples were capable of maintaining very high levels of total anthocyanin stability during storage (p < 0.05). On the other hand, ferulic acid and control samples had the longest estimated half-life during storage at pH 6.0. Intermolecular copigmentation successfully increased the half-life, colour retention and antioxidant activity of anthocyanins solution, with cya-nidin-3-O-glucoside (C3G) exhibiting the highest stability at both pH values. Overall, anthocya-nins from DBP in combination with chlorogenic or ferulic acid showed potential for commercial food applications

Production and properties of spray dried Clinacanthus nutans using modified corn starch as drying agent

Clinacanthus nutans leaves is a medicinal plant with promising therapeutic effect. The objective of this study was to produce C. nutans powder using a spray dryer and to evaluate its physicochemical properties, followed by physical observation after 3 months of storage at room temperature (21±1°C). C. nutans juice with and without the addition of 5% (w/v) of modified corn starch (MCS) was spray dried at a feed flow rate of 23 rpm, inlet air temperature of 160°C and outlet air temperature of 100°C. Results showed that significantly lower (p <0.05) values of water activity, moisture content, flowability, particle size, solubility, wettability and dispersibility times, while significantly higher (p<0.05) values of hygroscopicity, bulk and tapped densities were recorded as compared to the spray dried powder without the addition of MCS. These indicated that MCS as drying agent has significantly improved the powder properties and the physical appearance during storage. Furthermore, produced C. nutans powder had a significantly higher (p<0.05) IC50 values, percentage of inhibition and total phenolics content. Also, a strong correlation was observed between total phenolic and antioxidant activity, indicated that encapsulation using MCS successfully protected the thermally sensitive compounds which contributed to high antioxidant activity

Effect of acidified water on phenolic profile and antioxidant activity of dried blackcurrant (Ribes nigrum L.) pomace extracts

This study investigated the effect of acidified water at different pH values and extraction time on the phenolic profile (anthocyanins, hydroxycinnamic acids and flavonols), antioxidant activity and colour characteristics of dried blackcurrant pomaces (DBP) extracts. Extractions were carried out using acetic acid in water (pH 1.5, 2.0, 2.5 and 3.0) for 2 and 6 h at 30℃. Phenolics concentration in DBP extracts were influenced by the pH of acidified water (p<0.05), while extraction pH, extraction time and their combination had significant impact on total phenols, antioxidant activity and colour of DBP extracts (p<0.05). Regardless of the extraction time, very low pH (1.5) was positively associated with high amounts of anthocyanins, hydroxycinnamic acids and flavonols in DPB extracts. Also, extracts obtained at pH 1.5 had the highest amount of total phenols and antioxidant activity. Overall, acetic acid in water as extraction medium may influence greatly the phenolic profile and colour of DBP extracts, which could be utilised as alternative to synthetic food colourants

Effect of preharvest treatment using jasmonic acid and methyl jasmonate on the physicochemical properties and antioxidant activities of red-fleshed dragon fruit (Hylocereus polyrhizus L.)

This study investigated the effect of exogenous plant growth regulators (PGR), namely jasmonic acid (JA) and methyl jasmonate (MeJA), on the physicochemical properties of flesh and peels of red-fleshed dragon fruit (Hylocereus polyrhizus). The fruit was sprayed with 100 and 1,000 ppm of JA and MeJA at 15 and 22 days of anthesis and harvested after 35 days. Then, the flesh and peels were analyzed for total soluble solids (TSS), total betacyanins, betanin, total phenolics (TP), total flavonoids (TF), and color characteristics. The fruit peels contained significantly higher (p<0.05) TP and antioxidant activities compared to flesh. No significant difference was detected between the variables in the peels, except for significantly higher (p<0.05) of total betacyanins (~295.6 and ~299.9 mg/100 g) and TP (~614.1 and 566.1 mg GAE/100 g) were recorded in control and 100 ppm MeJA, respectively. In the flesh, 1,000 ppm MeJA-treated fruit possessed the highest total betacyanins (~139.2 mg/100 g), betanin (~356.0 mg/g), TP (~244.9 mg GAE/100 g), TF (~329.0 mg CE/100 g), Trolox equivalent antioxidant capacity (TEAC) (63.2 µmol TE/g) and reducing power (~21.5 µmol TE/g). Overall, 1,000 ppm MeJA was more effective in enhancing the accumulation of bioactive compounds and antioxidant activities in the flesh of red-fleshed dragon fruit compared to other PGR treatments

Optimisation of extrusion conditions for production of antioxidant-rich extruded breakfast cereals from purple sweet potato (Ipomoea batatas l.) and red rice using response surface methodology

Purple sweet potato powder (PSPP) is rich in anthocyanins and other polyphenols that provide excellent antioxidant and other biological activities with potential health benefits. In the present work, the response surface methodology (RSM) was used to optimise the extrusion processing conditions to develop healthy breakfast cereals. The independent variables studied included barrel temperature, screw speed, and feed moisture. The linear terms of barrel temperature and feed moisture content were found to be the significant (p &amp;lt; 0.05) factors affecting the product&#039;s functional and physicochemical properties. The expansion property of extrudate significantly (p &amp;lt; 0.001) increased at low temperature, high screw speed, and low feed moisture. The recommended optimum extrusion conditions of barrel temperature, screw speed, and feed moisture content were at 157.0°C, 126.0 rpm, and 13.0%, respectively; and under these optimum conditions, significantly high retention (75.0%) of anthocyanin content was detected. Furthermore, scanning electron micrographs depicted that the optimised breakfast cereals had a better cell structure with smoother and thinner cell walls than the non-optimised samples

Characterisation of local ikan pekasam and development of process for production of ikan pekasam from black pomfret (Parastromateus niger bloch)

Ikan pekasam is a fermented fish product produced in Malaysia. It is usually made from freshwater fish, and the main source of carbohydrate for the fermentation process is ground roasted rice. In this study, the sensory and physicochemical properties including pH, titratable acidity, salt concentration, amino acids, biogenic amines, trans- and cisurocanic acid (UCA), and organic acids of 15 commercially available samples were determined. The samples comprised ikan pekasam made from two types of commonly used freshwater fish, namely lampam jawa (Puntius gonionotus) and black tilapia (Oreochromis mossambicus), that had undergone either natural or acid-assisted fermentation. Acid-assisted fermented samples are those that included either tamarind pulp (Tamarindus indica) or Garcinia atroviridis dried slices as an ingredient in the fermentation process. The result showed that there were significant differences (p ≤ 0.05) in pH values, total UCA (trans- plus cis-UCA) and cis-UCA contents between naturally and acid-assisted fermented ikan pekasam samples. However, there were many similarities including titratable acidity, salt concentration, biogenic amine contents namely histamine, tyramine, putrescine, cadaverine, 2-phenylethylamine, spermidine, and tryptamine. Other than that, there was also no difference in organic acid contents including for lactic, acetic, succinic, formic, malic, oxalic, citric, L-pyroglutamic, and fumaric acids between naturally and acid-assisted fermented ikan pekasam samples. However, there were significant differences (p ≤ 0.05) in amino acid contents namely leucine, isoleucine, valine, phenylamine, tyrosine, methionine and cysteine between naturally and acid-assisted fermented ikan pekasam samples. Garcinic and tartaric acids were detected in all samples fermented with added G. artroviridis slices and tamarind pulp, respectively. In general, biogenic amine, UCA, and organic acid contents varied greatly in both natural and acid-assisted fermented ikan pekasam samples. Sensory evaluation of the fifteen samples based on 9-hedonic scale indicated that there was no difference (p > 0.05) between natural and acid-assisted fermented ikan pekasam. Based on the sensory acceptability results of commercial ikan pekasam samples, ikan pekasam was then prepared from black pomfret (Parastromateus niger) using two separate processes used in natural and acid-assisted fermentation. In the first part, the fish were naturally fermented after they were mixed with 20% (w/w) salt for 3 days, washed after which equal proportion (w/w) of ground roasted rice and 10% (v/w) water were added to each batch and then mixed. For acid-assisted fermentation in the second part, black pomfret (P. niger) was mixed 100% salt (w/w). After salting for 1 week, 50% (w/w) of ground roasted rice, 3% (w/w) tamarind pulp, and 150% (v/w) water were added to each batch and also mixed. After mixing, all of batches were allowed to ferment for up to five weeks at ambient temperature for further analysis. According to the results of analysis, there were significant differences (p ≤ 0.05) in physicochemical properties between different fermentation periods in both fermentation processes (natural and acid-assisted). For examples, pH value was significantly lower (p ≤ 0.05) in five weeks fermented black pomfret compared to two and zero weeks fermented black pomfret. Other than that, biogenic amine, trans- and cis-UCA, and organic acid contents were significantly higher (p ≤ 0.05) in five weeks fermented black pomfret compared to two and zero weeks fermented black pomfret. Furthermore, there were only slight differences in physicochemical and sensory properties between ikan pekasam made from black pomfret, a marine fish, and ikan pekasam made from freshwater fish (black tilapia and lampam jawa). For example, there were significant differences (p ≤ 0.05) in total biogenic amine, total UCA (transplus cis-UCA), total organic acid including lactic, acetic, malic, and formic acids contents. However, there were many similarities between ikan pekasam from marine and freshwater fish including pH values, titratable acidity, salt content, and especially biogenic amine concentrations, namely histamine, tyramine, putrescine, cadaverine, 2- phenylethylamine, spermidine, and tryptamine. Based on the sensory evaluation using quantitative descriptive analysis (QDA), the intensity of attributes in two and five weeks naturally fermented black pomfret such as sourness odor, cohesiveness of fish flesh, sourness, saltiness, fishy, and fermented flavors were significantly higher (p ≤ 0.05) than two and five weeks acid-assisted fermented black pomfret, respectively. Furthermore, the panelists could detect significant (p ≤ 0.05) differences in five weeks naturally and acid-assisted fermented black pomfret samples, whereas the intensity of color, roughness of fish skin, sourness odor, sourness flavor, saltiness flavor, bitterness flavor, fishy flavor, fermented flavor, crispiness of fish skin, and oiliness texture increased as the fermentation time was increased. Also, there was no significant difference (p > 0.05) in overall acceptability scores between naturally and acid-assisted fermented ikan pekasam from freshwater fish (black tilapia and lampam jawa) and marine fish (black pomfret). It could be concluded that Malaysian traditional fermented freshwater fish (black tilapia and lampam jawa) and marine fish (black pomfret) can be consumed without any health risks. In general, there was no difference in most of the physicochemical and sensory properties between naturally and acid-assisted fermented fish even from different type of fish or fermentation process. However, there were significant differences (p ≤ 0.05) in physicochemical properties between different fermentation periods in naturally and acid-assisted fermented black pomfret, respectively

The effects of heat treatment and modified atmosphere packaging on the storage stability of noni (Morinda citrifolia L.) fruit

Noni fruit (Morinda citrifolia L.) is a herbal remedy known for its therapeutic and nutritional value. However, it is perishable and subject to rapid postharvest deterioration that shortens its shelf life during storage. Therefore, this study investigated whether hot water dipping (HWD; 60°C, 1 min) and Modified Atmosphere Packaging (MAP; carbon dioxide and nitrogen) could prolong noni's shelf life. The noni physicochemical properties such as colour, firmness, weight loss, total soluble solids, titratable acidity and scopoletin content were monitored during six days of storage at room temperature. During storage, the noni skin colour changed from greenish-yellow to translucent yellow, but HWD storage was stopped on day 2 due to black spots' formation. The reduction of weight loss was significantly lowest in both MAP treatments (1.39–1.74%). Among these, N2-based had a significantly higher scopoletin content (27.12 mg/g) and firmness (0.8 N) compared to CO2-based, suggesting that it was the most effective postharvest treatment to efficiently prolong the shelf life and retained the quality and stability of noni during storage

Co-solvent selection for tocotrienol extraction from palm fatty acid distillate using supercritical carbon dioxide

A predictive model was devised for the estimation of the Kamlet-Taft (KT) dipolarity/polarisability (π*) parameter for binary mixtures of supercritical carbon dioxide (scCO2) and co-solvent. The model allows the selection of the best co-solvent for the extraction of tocotrienols from palm fatty acid distillate (PFAD). Ethanol, acetone, and isopropanol were separately used as co-solvents in the range of 0.05 – 0.15 mL/g for the experimental set-up at 20 MPa and 53°C for 300 min and a CO2 flow rate of 32 ± 5 g/min. The model’s estimations of π* for all these binary mixtures followed the trends for the extraction of tocotrienols. The π* values increased with the concentration of co-solvent in the binary system and tocotrienol extraction was directly proportional to the π* value, but only up to a particular value. Of the three co-solvents tested, ethanol was predicted to be the best to enhance tocotrienol extraction. With a 0.075 mL/g of ethanol, the extraction yield was 30.03a ± 0.03 mg/g, more than that achieved with pure scCO2 (16.45b ± 2.02 mg/g)