Lycopene and total phenolics of pink guava puree industry by-products (refiner, siever and decanter)
were evaluated after steam blanching at selected temperatures and times. Lycopene content was in the order of decanter > siever > refiner (7.3, 6.3 and 1.5 mg/100 g, respectively), and the content of total phenolics was in the order of refiner > siever > decanter (4434.1, 2881.3 and 1529.3 mg GAE/100 g, respectively). Regression coefficients for temperatures (x1) and times (x2) from multiple linear regression models of siever and decanter showed significant (p
Quality degradation is normally judge by monitoring independently the loss of a certain quality
attribute during storage. However, the rate of degradation for each of the quality attributes
present in a food product is not the same. This study focus on deterioration of vitamin C,
lycopene, total phenolics and antioxidant activity of ready-to-drink pink guava juice (PGJ)
during storage at elevated temperatures. Kinetic order, rate constant (k), activation energy
(Ea) and temperature coefficient (Q10) of the degradation were derived by applying Arrhenius
equation. The results obtained showed that freshly made PGJ contain 39.79±2.18 mg/100 mL
of vitamin C, 3.17±0.27 mg/L of lycopene, 28.08±4.11 mgGAE/100 mL of total phenolic
content (TPC) and 13.20±1.91 mMTE/100 mL of ferric reducing antioxidant power (FRAP).
All quality attributes measured in this study showed zero-order kinetic reaction. The results
also showed that FRAP has the highest Ea of 49.52 KJ/mol and Q10 of 1.80, followed by
vitamin C (Ea=41.49 KJ/mol; Q10=1.64), lycopene (Ea=31.75 KJ/mol; Q10=1.46), and lastly
TPC (Ea=14.11 KJ/mol; Q10=1.18). The predicted total depletion of each quality attribute
at refrigerated storage (5o
C) were 266 days for antioxidant activity, 158 days for vitamin C
and lycopene, and 63 days for total phenolics. This study provide useful information on the
degradation rate and availability of health beneficial and bioactive compounds present in fruit
juice beverage during storage.
A study has been conducted on pink guava juice (PGJ) fouling deposit. Several ex-situ experimental rigs were set-up to obtain PGJ fouling deposit, while the best ex-situ experimental rig was also selected. PGJ was heated at 93°C and its fouling deposit was obtained after 1 hour of heating. Then, it was used for the ex-situ cleaning study at 1 litre min-1, at several temperatures (70, 80 and 90°C), and in some chemical concentrations (1.6 v/v% of Maxiclean CP6 or 0.325 % OH-; 1.8 v/v% of Maxiclean CP6 or 0.369 % OH-; 2.0 v/v% of Maxiclean CP6 or 0.44 % OH-). The best cleaning combinations were investigated. Carbohydrate is the main content in the fouling deposit. The morphology of the deposit was studied using SEM and it showed an aggregated structure. The cleaning process improved as the temperature increased with the increasing of the chemical solution concentration. The shortest cleaning time was 40 minutes, for cleaning using 2.0 v/v % of Maxiclean CP6 (0.44 % OH-) at 90°C.
A novel aqueous two-phase system composed of a surfactant and sorbitol was employed for the first time to purify pectinase from Psidium guajava. The influences of different parameters, including the type and concentration of the surfactant and the concentration and composition of the surfactant/sorbitol ratio, on the partitioning behavior and recovery of pectinase were investigated. Moreover, the effects of system pH and the crude load on purification fold and the yield of purified pectinase were studied. The experimental results indicated that the pectinase was partitioned into surfactant-rich top phase, and the impurities were partitioned into the sorbitol-rich bottom phase with the novel method involving an ATPS composed of 26% (w/w) Triton X-100 and 23% (w/w) sorbitol at 54.2% of the TLL crude load of 20% (w/w) at pH 6.0. The enzyme was successfully recovered by this method with a high purification factor of 15.2 and a yield of 98.3%, whereas the phase components were also recovered and recycled at rates above 96%. This study demonstrated that this novel ATPS method can be used as an efficient and economical alternative to the traditional ATPS for the purification and recovery of the valuable enzyme.
The guava processing industry in Malaysia produces by-products in the form of seed core and peel. These by-products can be regarded as underused resources but there are concerns about their composition that prevent their use in the food and feed industries. This study aims to analyze the respective effects of heat treatments (boiling or autoclaving) and germination periods on the nutritional composition and phytochemical content of guava seeds. The guava seeds were found to contain 618, 78, 72, and 5 mg/g dry weight total dietary fiber, fat, protein, and ash, respectively. The tannin and saponin contents, but not the phytic acid content, were below the respective anti-nutritional thresholds. The heat treatments did not affect the total dietary fiber and ash contents but reduced all other chemical components to different extents (15-91%). Boiling did not reduce the phytic acid content substantially but autoclaving caused a reduction of 91% to a level below the anti-nutritional threshold. Germination for 14 days caused a significant reduction in nutrient contents in the range of 16-79%. Germination also reduced the phytic acid content by 90% in the seed but did not significantly affect the saponin content. Thus, guava seed can be treated thermally or germinated to manipulate its chemical composition to enable its use in the food and feed industries.
The effect of leaf extracts of Psidium guajava and Piper betle on prolonging vase life of cut carnation flowers was studied. "Carola" and "Pallas Orange" carnation flowers, at bud stage, were pulsed 24 hours with a floral preservative. Then, flowers were placed in a vase solution containing sprite and a "germicide" (leaf extracts of P. guajava and P. betle, 8-HQC, or a copper coin). Flowers treated with 8-HQC, copper coin, and leaf extracts had longer vase life, larger flower diameter, and higher rate of water uptake compared to control (tap water). The leaf extracts of P. guajava and P. betle showed highest antibacterial and antifungal activities compared to the other treatments. Both showed similar effects on flower quality as the synthetic germicide, 8-HQC. Therefore, these extracts are likely natural germicides to prolong vase life of cut flowers.
Guava (Psidium guajava) leaves are commonly used in the treatment of diseases. They are considered a waste product resulting from guava cultivation. The leaves are very rich in essential oils (EOs) and volatiles. This work represents the detailed comparative chemical profiles of EOs derived from the leaves of six guava varieties cultivated in Egypt, including Red Malaysian (RM), El-Qanater (EQ), White Indian (WI), Early (E), El-Sabahya El-Gedida (ESEG), and Red Indian (RI), cultivated on the same farm in Egypt. The EOs from the leaves of guava varieties were extracted by hydro-distillation and analyzed with GC-MS. The EOs were categorized in a holistic manner using chemometric tools. The hydro-distillation of the samples yielded 0.11-0.48% of the EO (v/w). The GC-MS analysis of the extracted EOs showed the presence of 38 identified compounds from the six varieties. The sesquiterpene compounds were recorded as main compounds of E, EQ, ESEG, RI, and WI varieties, while the RM variety attained the highest content of monoterpenes (56.87%). The sesquiterpenes, β-caryophyllene (11.21-43.20%), and globulol (76.17-26.42%) were detected as the major compounds of all studied guava varieties, while trans-nerolidol (0.53-10.14) was reported as a plentiful compound in all of the varieties except for the RM variety. A high concentration of D-limonene was detected in the EOs of the RM (33.96%), WI (27.04%), and ESEG (9.10%) varieties. These major compounds were consistent with those reported for other genotypes from different countries. Overall, the EOs' composition and the chemometric analysis revealed substantial variations among the studied varieties that might be ascribed to genetic variability, considering the stability of the cultivation and climate conditions. Therefore, this chemical polymorphism of the studied varieties supports that these varieties could be considered as genotypes of P. guajava. It is worth mentioning here that the EOs, derived from leaves considered to be agricultural waste, of the studied varieties showed that they are rich in biologically active compounds, particularly β-caryophyllene, trans-nerolidol, globulol, and D-limonene. These could be considered as added value for pharmacological and industrial applications. Further study is recommended to confirm the chemical variations of the studied varieties at a molecular level, as well as their possible medicinal and industrial uses.
Diabetes mellitus (DM) and its complications are a severe public health concern due to the high incidence, morbidity, and mortality rates. The present study aims to synthesize and characterize silver nanoparticles (AgNPs) using the aqueous leaf extract of Psidium guajava (PGE) for investigating its antidiabetic activity. Psidium guajava silver nanoparticles (PGAg NPs) were prepared and characterized by various parameters. The in vivo study was conducted using PGE and PGAg NPs in Streptozotocin (STZ)-induced diabetic rats to assess their antidiabetic properties. STZ of 55 mg/kg was injected to induce diabetes. The PGE, PGAg NPs at a dose of 200 and 400 mg/kg and standard drug Metformin (100 mg/kg) were administered daily to diabetic rats for 21 days through the oral route. Blood glucose level, body weight changes, lipid profiles, and histopathology of the rats' liver and pancreas were examined. In the diabetic rats, PGE and PGAg NPs produced a drastic decrease in the blood glucose level, preventing subsequent weight loss and ameliorating lipid profile parameters. The histopathological findings revealed the improvements in pancreas and liver cells due to the repercussion of PGE and PGAg NPs. A compelling effect was observed in all doses of PGE and PGAg NPs; however, PGAg NPs exhibited a more promising result. Thus, from the results, it is concluded that the synthesized PGAg NPs has potent antidiabetic activity due to its enhanced surface area and smaller particle size of nanoparticles.
A study was carried out to compare the cookie dough properties and cookie quality made out
of pink guava oil-palm stearin blends and lard (LD). Since LD is prohibited under religious
restrictions, plant shortenings were prepared by mixing pink guava seed oil with palm stearin
(PGO/PS) in different ratios: PGO-1, 40:60; PGO-2, 45:55; PGO-3, 50:50; PGO-4; 55:45 as
replacement. The effect of these formulated plant-based shortenings and LD shortening were
compared on dough rheological properties and cookie quality. Rheology and hardness of the
cookie dough were evaluated using Texture Analyser (TA). Cookie hardness was evaluated
with TA while cookie surface colors were measured using the CIE L*a*b* colorimetric system.
Among the samples, cookies made out of PGO-2 with the ratio 45:55 (PGO:PS) performed the
best substitute for LD to be used as shortening in cookies. PGO-2 also displayed the closest
similarity to LD in cookies for hardness, size and thickness, cracking size as well as colour.
As PGO-2 was a shortening formulated with plant-based ingredients, it could comply with the
halal and toyyiban requirements.
Plant extracts mixture (PEM) and its individual constituent plant extracts(Psidium sp., Mangifera sp., Mentha sp.) are known to have an anti-adhering effect towards oral bacteria in the single-species biofilm. To date, the adhering ability of the early and late plaque colonisers (Streptococcus sanguinis and Streptococcus mutans) to PEM-treated experimental pellicle have not been investigated in dual-species biofilms.
The steady-state flow test was conducted on pink-fleshed guava, pink-fleshed pomelo and soursop juice concentrates using a rheometer to understand its rheological behaviour. The power law model was used and a master-curve was created using the shear rate-temperature-concentration superposition technique to predict rheological properties from a wide range of temperatures and concentrations. All three juice concentrates undergo a double horizontal shift whilst the pink-fleshed guava required an additional vertical shift. The final equations show shear-thinning behaviour of pink-fleshed guava, pink-fleshed pomelo and soursop with flow behaviour index of 0.2217, 0.7507 and 0.6347, respectively. The final master-curve predicts shear stress at wide range of shear rates, i.e. between 10-2 and 106 s-1 for the pink-fleshed guava, 100 and 106 s-1 for the pink-fleshed pomelo and 100 and 107 s-1 for the soursop. The results provide useful information and effective technique to predict fruit juice concentrates behaviour affected by heat changes during processing.
Antioxidant properties of both fresh and convection oven-dried guavas (Psidium guajava L.) were determined. Guava slices of 1.0 cm wide, 3.0 cm long and 0.5cm thick (20 g) were subjected to convection drying at 40°C for 9, 12 and 14 hours, respectively, and their water activity, total phenolic content (TPC) and antioxidant activities were measured. Guavas that had been subjected to drying for 9, 12 and 14 hours were shown to achieve the water activity of 0.36-0.49. Ascorbic Acid Equivalent Antioxidant Capacity (AEAC) of guava was found to decrease for all the drying durations. Convection oven-drying of guava for 12 and 14 hours showed a significant decrease in TPC (p < 0.01) and Ferric Reducing Power Assay (FRP) (p < 0.01). Nine hours of convection oven-drying was shown to retain most of the TPC, AEAC and FRP of guava.
The redfleshed pulp discarded from pink guava puree industry is a rich source of lycopene and pectin. In this study, we developed a facile extraction process employing water as the primary extraction medium to isolate the lycopene and pectin from pink guava decanter. When the decanter was suspended in water, the complexation of lycopene and pectin formed the cloudy solution, where the colloidal complexes were recovered through centrifugation. The presence of lycopene and pectin in the complex was confirmed by the spectroscopic, microscopic and chromatographic analyses. The lycopene fractionated from the complexes had a purity level of 99% and was in all-trans configuration. The colloidal complexes yielding the highest concentration of lycopene was obtained at pH 7, 1% (w/v) solid loading and 25 °C. The experimental data of time-course extraction of lycopene-pectin complex were best fitted with two-site kinetic model, hinting the fast- and slow-release phases in the extraction process.
In this study, the bacteriostatic effect of Piper betle and Psidium guajava extracts on selected early dental plaque bacteria was investigated based on changes in the doubling time (g) and specific growth rates (micro). Streptococcus sanguinis, Streptococcus mitis and Actinomyces sp. were cultured in Brain Heart Infusion (BHI) in the presence and absence of the extracts. The growth of bacteria was monitored periodically every 15 min over a period of 9 h to allow for a complete growth cycle. Growth profiles of the bacteria in the presence of the extracts were compared to those in the absence and deviation in the g and micro were determined and analyzed. It was found that the g and mu were affected by both extracts. At 4 mg mL(-1) of P. betle the g-values for S. sanguinis and S. mitis were increased by 12.0- and 10.4-fold, respectively (p < 0.05). At similar concentration P. guajava increased the g-value by 1.8- and 2.6 -fold, respectively (p < 0.05). The effect on Actinomyces sp. was observed at a much lower magnitude. It appears that P. betle and P. guajava extracts have bacteriostatic effect on the plaque bacteria by creating a stressed environment that had suppressed the growth and propagation of the cells. Within the context of the dental plaque, this would ensure the attainment of thin and healthy plaque. Thus, decoctions of these plants would be suitable if used in the control of dental plaque.
Modelling studies of guava drying and quality are presented using theoretical and statistical models by varying temperature from 55 to 75 °C and slice thickness from 3 to 9 mm. The quality of dried fruit was measured for its water activity, colour, vitamin C, and texture. The superposition technique with Midilli-Kucuk model showed efficiency in modelling the drying process with R (2) = 0.9991. The second-order polynomial equations adequately described the quality of dried guava with regression coefficient, R (2) > 0.7. Drying time was a good function of temperature and thickness (P
Presently, functional foods and nutraceuticals are gaining immense importance in the prevention of various maladies through dietary regimen module. Consumption of fruits and vegetables based diet has pursuit a range of bioactive components, especially phytochemicals targeting life threatening ailments. In this context, lycopene is an extensively studied antioxidant potentially present in watermelon, tomato, pink guava etc. Watermelon is one of the unique sources having readily available cis-isomeric lycopene. The distinctive aroma of watermelon is imparted by medium- and short-chain fatty acids along with geranial, ß-ionone and neral. Its consumption has been escalated owing to rich nutritional profile and allied health benefits. It is effective in reducing the extent of cancer insurgence, cardiovascular disorders, diabetes and macular diseases. The structural characteristics, physiochemical properties and therapeutic effects of lycopene are the limelight of the manuscript. However, further research investigations are still needed to address the health enhancing potential of watermelon lycopene.
This study aimed to investigate the effects of the ultrasound-assisted extraction conditions on the yield, specific activity, temperature, and storage stability of the pectinase enzyme from guava peel. The ultrasound variables studied were sonication time (10-30 min), ultrasound temperature (30-50 °C), pH (2.0-8.0), and solvent-to-sample ratio (2:1 mL/g to 6:1 mL/g). The main goal was to optimize the ultrasound-assisted extraction conditions to maximize the recovery of pectinase from guava peel with the most desirable enzyme-specific activity and stability. Under the optimum conditions, a high yield (96.2%), good specific activity (18.2 U/mg), temperature stability (88.3%), and storage stability (90.3%) of the extracted enzyme were achieved. The optimal conditions were 20 min sonication time, 40 °C temperature, at pH 5.0, using a 4:1 mL/g solvent-to-sample ratio. The study demonstrated that optimization of ultrasound-assisted process conditions for the enzyme extraction could improve the enzymatic characteristics and yield of the enzyme.
The optimization of pink guava was executed using central composite face-centred design to optimize the spray drying parameters of inlet temperature, maltodextrin concentration (MDC) and feed flow (FF). The experimental results were significantly (p<0.01) fitted into second-order polynomial models to describe and predict the response quality in terms of the final moisture, particle size and lycopene with R2 of 0.9749, 0.9616, and 0.9505, respectively. The final moisture content significantly (p<0.01) decreased with increasing inlet temperature and MDC, whereas the particle size increased. In contrast, the lycopene content significantly (p<0.01) decreased with the higher temperature and increased with increasing MDC. However, according to multiple response optimization, the optimum conditions of 150°C inlet temperature, 17.12% (w/v) MDC and 350 mL/h FF-predicted 3.10% moisture content, 11.23 μm particle size and 58.71 mg/100 g lycopene content. The experimental observation satisfied the predicted model within the acceptable range of the responses.
This study aimed to determine the biofilm formation ability by Salmonella Typhi on cucumber, mango and guava surface, as well as to determine the relationship between time contact and biofilm formation. Crystal violet assay was performed to quantify the biofilm formation based on the value of optical density at 570 nm of the destaining crystal violet at the specific interval time. The result showed that the attachment of the bacterial cells on the fresh produce surface increased with the contact time. The readings of OD570at time 12 h for cucumber, mango and guava surfaces were 0.824, 0.683 and 0.598, respectively, indicating that the biofilm formation by Salmonella Typhi on different fresh produce surface varied with time. Since the result showed that Salmonella Typhi formed biofilm on fresh produce surfaces, hygienic practice from farm to fork including handling, processing, distribution and storage of the fresh produce should be of concern.
Guava is a climacteric fruit which has high nutritional content. It is a highly perishable fruit, undergoes rapid postharvest ripening in a few days under ambient condition. This paper aims to determine the effect of palm stearin and palm kernel olein blends on maintaining the quality of guava during storage. Two different coating formulations of palm stearin (PS) and palm kernel olein (PKOo) blends (1:1 and 3:2) were analysed for their slip melting point (SMP), cohesiveness, viscosity and density. Beeswax was used as a commercial coating for comparison whiles the uncoated guava was used as control. These coatings were applied onto guavas by hand-wipe technique using a sponge. Guavas were dried in corrugated fibre board boxes and stored in an air-conditioned room maintained at 20°C while a chiller maintained at 10°C was used for chilled temperature. Coating pick up, thickness and surface area were measured while guava properties were analysed for coating effect on weight loss, O2 and CO2 gases, firmness and glossiness during storage at ambient temperature (20°C) for 21 days and chilled temperature (10ºC) for 30 days. Microstructure analysis was conducted within 2 days of coating at ambient temperature (20ºC). The results obtained indicated that 1:1 PSPKOo blends had higher cohesiveness compared to beeswax. Both PSPKOo blends significantly (p