Sustainable papaya plant waste and green tea residue composite films integrated with starch and gelatin for active food packaging applications

This study explores the sustainable utilization of wastes from a papaya plant (papaya peels (PP), papaya seeds (PS), leaf-stem (PL)) and dried green tea residues (GTR) for the synthesis of bioplastics. The dried GTR were individually blended with each papaya waste extract and then boiled in water to get three composite papaya plant waste-green tea supernatants. Potato starch and gelatin-based functional films were prepared by integrating each with the composite papaya waste-green tea supernatant liquid. This work introduces a dissolved organic matter (DOM) study to the field of bioplastics, with the goal of identifying the organic components and macromolecules inherent in the PW supernatants. When compared with the films prepared solely from papaya waste (PW) supernatants, PW-GTR composite supernatant films prevent UV light transmission with superior antioxidant and mechanical properties. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction spectroscopy (XRD), and atomic force microscopy (AFM) were utilized to characterize the starch and gelatin PW-GTR films. Owing to the exceptional antioxidant, UV barrier, and remarkable biodegradable properties of the starch/PW/GTR and gelatin/PW/GTR composite films, make them ideal for use in food packaging applications.

A novel approach to increase calcium and fiber content in pasta using kadamb fruit (Neolamarckia cadamba) powder and study of functional and structural characteristics

Kadamb is a unique and underutilized fruit having rich nutritional profile. The utilization of kadamb fruit in value addition is very limited. In this study, pasta was made using kadamb fruit powder (KFP). The effect of fortification of KFP on the quality parameters (color, solid loss, percent expansion, hardness, bulk density, and overall acceptability) of pasta was studied. Pasta was prepared using semolina as the base ingredient, and various proportions of KFP (ranging from 0 to 20%) were added for fortification. Dietary fiber and calcium contents of dry pasta were increased from 5.21 ± 0.02 to 15.36 ± 0.02 and 17.57 ± 0.15 to 37.97 ± 0.03, respectively. As the proportion of KFP increased, the cooking time, hardness, and percent solid loss of the cooked pasta also increased. The highest values for overall acceptability, hardness, cooking solid loss, and bulk density were achieved with 10% KFP and 90% semolina were 7.93 ± 0.41, 19.92 ± 0.21 N, 6.30 ± 0.46%, and 331.67 ± 9.60 kg/m3 respectively. Percent expansion of the pasta was noted to be around 98.33 ± 6.5%. The optimal proportion of KFP was found to be 10% for achieving the best overall quality attributes. FTIR (Fourier-transform infrared spectroscopy) and SEM (scanning electron microscopy) analyses were conducted on the pasta, confirming the presence of functional groups and revealing structural changes due to fiber content of KFP. KFP can be used to create functional and nutritious food products, and further research could explore its application in other food formulations as well.

Physical and Chemical Properties of Vegetable Films Based on Pumpkin Purée and Biopolymers of Plant and Animal Origin

Highly methylated apple pectin (HMAP) and pork gelatin (PGEL) have been proposed as gelling agents for pumpkin purée-based films. Therefore, this research aimed to develop and evaluate the physiochemical properties of composite vegetable films. Granulometric analysis of film-forming solutions showed a bimodal particle size distribution, with two peaks near 25 µm and close to 100 µm in the volume distribution. The diameter D_4.3, which is very sensitive to the presence of large particles, was only about 80 µm. Taking into account the possibility of creating a polymer matrix from pumpkin purée, its chemical characteristic was determined. The content of water-soluble pectin was about 0.2 g/100 g fresh mass, starch at the level of 5.5 g/100 g fresh mass, and protein at the level of about 1.4 g/100 g fresh mass. Glucose, fructose, and sucrose, the content of which ranged from about 1 to 1.4 g/100 g fresh mass, were responsible for the plasticizing effect of the purée. All of the tested composite films, based on selected hydrocolloids with the addition of pumpkin purée, were characterized by good mechanical strength, and the obtained parameters ranged from about 7 to over 10 MPa. Differential scanning calorimetry (DSC) analysis determined that the gelatin melting point ranged from over 57 to about 67 °C, depending on the hydrocolloid concentration. The modulated differential scanning calorimetry (MDSC) analysis results exhibited remarkably low glass transition temperature (Tg) values, ranging from -34.6 to -46.5 °C. These materials are not in a glassy state at room temperature (~25 °C). It was shown that the character of the pure components affected the phenomenon of water diffusion in the tested films, depending on the humidity of the surrounding environment. Gelatin-based films were more sensitive to water vapor than pectin ones, resulting in higher water uptake over time. The nature of the changes in water content as a function of its activity indicates that composite gelatin films, with the addition of pumpkin purée, are characterized by a greater ability to adsorb moisture from the surrounding environment compared to pectin films. In addition, it was observed that the nature of the changes in water vapor adsorption in the case of protein films is different in the first hours of adsorption than in the case of pectin films, and changes significantly after 10 h of the film staying in an environment with relative humidity RH = 75.3%. The obtained results showed that pumpkin purée is a valuable plant material, which can form continuous films with the addition of gelling agents; however, practical application as edible sheets or wraps for food products needs to be preceded with additional research on its stability and interactions between films and food ingredients.

Effect of cellulose and gum derivatives on physicochemical, microstructural and prebiotic properties of foam-mat dried red banana powder

Fruit sugars are gaining attention for their nutraceutical benefits. High sugar in ripe and over-ripe bananas makes them difficult for convective drying. In this study, red banana (RB) pulp was added with different gum derivatives as foaming agent (FA) (4 % w/w) viz., acacia gum(GA), carrageenan (CG) and gelatine(GE). Maltodextrin and carboxymethyl-cellulose were added as foam-stabilizers (FS). FA addition resulted in low density foam (RBGE-50 % reduction) with improved foam stability (RBGA-94.42 %). Powders were low in hygroscopicity (RBGA-18.62 g 100 g ^-1) with optimum flowability. The particle size (54.95 to 69.86 μm) of RB powder increased with gum derivatives addition. Secondary metabolites varied significantly in powder samples. Positive correlation of secondary metabolites with DPPH assay was observed. RBGA showed higher prebiotic activity (0.68) and supported the growth of tested Lactobacillus strain. Therefore, foam-mat dried RB powder with GA could be used in food formulation as low-cost alternative fruit sugar with higher nutritional, functional and prebiotic properties.

Hygroscopic Properties of Sweet Cherry Powder: Thermodynamic Properties and Microstructural Changes

Understanding sorption isotherms is crucial in food science for optimizing the drying processes, enhancing the shelf-life of food, and maintaining food quality during storage. This study investigated the isotherms of sweet cherry powder (SCP) using the static gravimetric method. The experimental water sorption curves of lyophilized sweet cherry powder were determined at 30°C, 40°C, and 50°C. The curves were then fitted to six isotherm models: Modified GAB, Halsey, Smith, Oswin, Caurie, and Kühn models. To define the energy associated with the sorption process, the isosteric sorption heat, differential entropy, and spreading pressure were derived from the isotherms. Among the six models, the Smith model is the most reliable in predicting the sorption of the cherry powder with a determination coefficient (R2) of 0.9978 and a mean relative error (MRE) ≤1.61. The values of the net isosteric heat and differential entropy for the cherry increased exponentially as the moisture content decreased. The net isosteric heat values varied from 10.63 to 90.97 kJ mol−1, while the differential entropy values varied from 27.94 to 273.39 J. mol−1K−1. Overall, the enthalpy-entropy compensation theory showed that enthalpy-controlled mechanisms could be used to regulate water adsorption in cherry powders.

A freeze-thaw PVA hydrogel loaded with guava leaf extract: physical and antibacterial properties

A polyvinyl alcohol (PVA) hydrogel loaded with guava leaf extract (GLE) has potential applications as a wound dressing with good antibacterial activity. This study succeeded in fabricating a PVA hydrogel containing GLE using the freeze–thaw (FT) method. By varying the GLE concentration, we can adjust the physical properties of the hydrogel. The addition of GLE results in a decrease in cross-linking during gelation and an increase in the pore size of the hydrogels. The increase of the pore size made the swelling increase and the mechanical strength decrease. The weight loss of the hydrogel also increases because the phosphate buffer saline (PBS) dissolves the GLE. Increasing the GLE concentration caused the Fourier-transform infrared (FTIR) absorbance peaks to widen due to hydrogen bonds formed during the FT process. The crystalline phase was transformed into an amorphous phase in the PVA/GLE hydrogel based on the X-ray diffraction (XRD) spectra. The differential scanning calorimetry (DSC) characterization showed a significant decrease in the hydrogel weight over temperatures of 30–150 °C due to the evaporation of water from the hydrogel matrix. The zone of inhibition of the PVA/GLE hydrogel increased with antibacterial activity against Staphylococcus aureus of 17.93% per gram and 15.79% per gram against Pseudomonas aeruginosa.

A polyvinyl alcohol (PVA) hydrogel loaded with guava leaf extract (GLE) has potential applications as a wound dressing with good antibacterial activity.

Physicochemical and Thermal Characteristics of Onion Skin from Fifteen Indian Cultivars for Possible Food Applications

Every year tons of onion waste is produced worldwide. The dried outer onion skin contributed up to 70% of this waste. Outer-dried skins of fifteen prominent onion cultivars from India were selected for the study. A comparative study was done for proximate profiling, thermal characteristics, functional grouping, and mineral contents. Skin of cv. “NHRDF Red” contained the highest amount of crude protein (5.97 ± 0.15 g/100 g), ash (12.24 ± 0.59 g/100 g), and fiber (8.28 ± 0.20 g/100 g), whereas cv. “Pusa Red” possessed the highest amount of total fat (0.47 ± 0.02 g/100 g) and the maximum carbohydrates (76.66 ± 0.56 g/100 g) were found in “Pusa Riddhi.” Mineral analysis showed that cv. “NHRDF Red” had the maximum concentration of all 9 minerals along with sulphur content. Fourier transform infrared spectroscopy analysis explored the various metabolites present in each cultivar. The thermal analysis explored cv. “Agrifound Dark Red” as highly thermally stable having 70.98% residual mass. The lowest Tg temperature range was found between 64.4°C and 90.6°C for “Agrifound Dark Red.” Skin of cv. “NHRDF Red” was reported as the best source of protein, fiber, and minerals, which may be utilized for developing a food product.

Production of spray-dried enzyme-liquefied papaya (Carica papaya L.) powder

Abstract Water removal during drying process consumes energy and lead to high production cost. Hence, enzymatic mash treatment was proposed to reduce the usage of water to produce feed concentration that is suitable for drying. In this study, papaya powder was prepared from papaya puree treated with 1.0% v/w of Pectinex® Ultra SP-L, a pectinase enzyme, with incubation under 50 °C up to 2 hours. The liquefied papaya puree was spray-dried at selected maltodextrin concentrations (10% to 50% w/w of papaya puree) and inlet temperatures (140 °C to 180 °C). The physico-chemical properties of papaya puree, spray-dried powder, and reconstituted powder were assessed. Results showed that an increase in maltodextrin concentration led to lower process yield, lower moisture content and hygroscopicity, and better solubility. The powder produced was brighter in colour (L*) and less yellowish (b*). The papaya puree added with 20% maltodextrin achieved the highest process yield (74.91% ± 9.15%) and better solubility (69.60 ± 0.48 s/g) with optimal moisture content (5.21% ± 0.15% dry basis) and hygroscopicity (24.79% ± 0.58%) which was selected as optimal concentration. Meanwhile, increasing spray drying inlet temperatures led to a reduction in moisture content (26%) but did not significantly affect (p > 0.05) water activity, hygroscopicity, bulk density and colour of spray-dried papaya powders. The inlet temperature of 150 °C achieved the highest solubility (48.17 ± 4.51 s/g) with moderate process yield (74.01% ± 7.69%) and moisture content (5.91% ± 0.70% dry basis) which was considered as optimal drying temperature. The reconstituted powder showed no significant effect in viscosity, pH, and colour regardless of the different maltodextrin concentrations and inlet temperatures used. The optimized spray powder showed no significant difference with initial spray drying feed in total soluble solids, pH, and b* value.