Bio-based films prepared with apple pomace: Volatiles compound composition and mechanical, antioxidant and antibacterial properties

Selected fruit pomaces: Nutritional profile, health benefits, and applications in functional foods and feeds

The utmost objective of every nation is to achieve zero hunger and ensure the health and well-being of its population. However, in impoverished nations, particularly in rural areas, such issues persist on a daily basis. Currently, there is a growing demand for fruit consumption due to their potential health benefits. Surprisingly, their most prevalent by-product is pomace, which is produced in millions of tonnes and is usually discarded as waste after processing or consumption. Even food produced with these kinds of raw resources can contribute to the objective of eradicating world hunger. Owing to these advantages, scientists have begun evaluating the nutritional content of various fruit pomace varieties as well as the chemical composition in different bioactive constituents, which have significant health benefits and can be used to formulate a variety of food products with notable nutraceutical and functional potential. So, the purpose of this review is to understand the existing familiarity of nutritional and phytochemical composition of selected fruit pomaces, those derived from pineapple, orange, grape, apple, and tomato. Furthermore, this article covers pre-clinical and clinical investigations conducted on the selected fruit pomace extracts and/or powder forms and its incorporation into food products and animal feed. Adding fruit pomaces reduces the glycemic index, increases the fibre content and total polyphenolic contents, and reduces the cooking loss, etc. In animal feeds, incorporating fruit pomaces improves the antioxidant enzyme activities, humoral immune system, and growth performance and reduces methane emission.

Multipurpose arrowroot starch films with anthocyanin-rich grape pomace extract: Color migration for food simulants and monitoring the freshness of fish meat

Extraction of anthocyanins from grape pomace, is a way of valuing these abundant by-products with low added value. Its integration into films may allow it to be used in bioactive packaging, which creates new color and solubility properties for food and smart food packaging which tracks the freshness of fish. Films of arrowroot starch added with different concentrations of grape pomace extract (GPE) were flexible to handle, reddish and presented a high content of anthocyanins. The water vapor permeability increased by 17 %, while the tensile strength of arrowroot starch film decreased by 79 % with the addition of 40 % GPE. The addition of GPE increased the solubility of the starch film in aqueous and lipid food simulants by 121 and 119 %. The GPE pigment preferentially migrated to the aqueous simulant due to the hydrophilic nature of anthocyanins and starch. The GPE film showed distinguishable color changes in different pH buffer solutions from pink at pH 2 to light blue at pH 7 and slightly yellowish green at pH 10. When the composite films were monitored for fish meat freshness, the change in color of the film from reddish pink to slightly green after 96 h of storage at 25 °C was evident.

Chemical profile and biological properties of the Piper corcovadense C.DC. essential oil

The essential oil from Piper corcovadense D.DC. (EOPc), an important plant belonging to the Piperaceae family, which is commonly found in the northern region of Brazil and poorly explored scientifically, was used in this study. Thus, the EOPc was characterized chemically by Gas Chromatography/Mass Spectrometry (GC/MS) and the antioxidant and antimicrobial activities and their potential effects on cutaneous melanoma (SK-MEL-28) and healthy peripheral blood mononuclear (PBMC) cells were determined. The major compounds identified in the EOPc were: trans-sesquisabinene hydrate, trans-caryophyllene, β-pinene, trans-β-farnesene, 14-hydroxycaryophyllene, limonene and p-cymene. The EOPc demonstrated antioxidant activity as evaluated by Folin-Ciocalteu reagent (FC) reducing capacity, DPPH, and ABTS methods. The values found were respectively 5.41 ± 0.17 mg GAE mL-1 (GAE: Gallic acid equivalent), 2.88 ± 0.17 µmol TE mL-1 (TE: Trolox equivalent) and 6.26 ± 0.02 µmol TE mL-1. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined for different bacterial strains. The EOPc at a concentration of 2.61 µg mL-1 exhibited both bactericidal and bacteriostatic properties against Escherichia coli. The EOPc showed potential antitumor activity as it reduced the cell viability of human cutaneous melanoma cells SK-MEL-28. Besides, the EOPc did not exhibit cytotoxic activity against healthy PBMCs, indicating that it does not harm healthy cells at the tested concentrations. The EOPc increased the levels of ROS at concentrations of 250 µg mL-1. The EOPc also did not stimulate the mobilization of endogenous antioxidant defenses, as assessed by total thiol (PSH) and non-protein thiols (NPSH). Thus, the study suggests that the EOPc has antioxidant and antimicrobial properties due to the presence of specific compounds. It also exhibits antitumor potential against cutaneous melanoma cells while showing no cytotoxicity to healthy PBMCs. It directly influenced ROS levels at the highest tested concentration in the cells, suggesting an antitumor effect related to the intrinsic apoptosis pathway. Nevertheless, while the study has initial findings, the results are promising and indicate an attractive biological potential of P. corcovadense, mainly in human cutaneous melanoma cells.

Fruit pomace as a promising source to obtain biocompounds with antibacterial activity

The demand for natural compounds to replace synthetic additives has aroused the interest of different sectors of society, especially the scientific community, due to their safety, biocompatibility, biodegradability and low toxicity. Alternative sources for antimicrobial compounds have been explored, such as fruit pomace. These by-products have essential compounds in their composition with different potential for application in food and packaging. In this context, this review systematizes the use of pomace from different fruits as a source of antibacterial compounds. Also, it summarizes the extraction methods and the applications of these compounds. Grape pomace, cranberry, and apple extracts are the most explored for antibacterial control, especially against genus Listeria, Salmonella, Staphylococcus, and Escherichia. In addition, phenolic acids, anthocyanins, flavonoids, and proanthocyanins are the main compounds identified in the studied fruit pomace extracts. In the reviewed articles, the biocompounds recovery is performed by methods with the absence of high temperatures (>80 °C); in some studies, the solid-liquid extraction method at mild temperatures (<30 °C) was well explored, using ethanol and water as solvent. The use of fruit processing by-products for bacterial control highlights the possibility of favoring the three pillars of sustainability (social, economic, and environmental) in the food industry.

Fruit waste: a current perspective for the sustainable production of pharmacological, nutraceutical, and bioactive resources

Fruits are crucial components of a balanced diet and a good source of natural antioxidants, that have proven efficacy in various chronic illnesses. Various kinds of waste generated from fruit industries are considered a global concern. By utilizing this fruit waste, the international goal of "zero waste" can be achieved by sustainable utilization of these waste materials as a rich source of secondary metabolites. Moreover, to overcome this waste burden, research have focused on recovering the bioactive compounds from fruit industries and obtaining a new strategy to combat certain chronic diseases. The separation of high-value substances from fruit waste, including phytochemicals, dietary fibers, and polysaccharides which can then be used as functional ingredients for long-term health benefits. Several novel extraction technologies like ultrasound-assisted extraction (UAE), pressurized liquid extraction (PLE), and supercritical fluid extraction (SFE) could provide an alternative approach for successful extraction of the valuable bioactives from the fruit waste for their utilization as nutraceuticals, therapeutics, and value-added products. Most of these waste-derived secondary metabolites comprise polyphenols, which have been reported to have anti-inflammatory, insulin resistance-treating, cardiovascular disease-maintaining, probiotics-enhancing, or even anti-microbial and anti-viral capabilities. This review summarizes the current knowledge of fruit waste by-products in pharmacological, biological, and probiotic applications and highlights several methods for identifying efficacious bioactive compounds from fruit wastes.

Evolution of physico-chemical parameters, microorganism diversity and volatile organic compound of apple pomace exposed to ambient conditions

In apple processing, waste material known as apple pomace amounts to 45% of production volumes. When this residue is stored in open-air for its stabilization and potential uses, Volatile Organic Compounds (VOCs) are produced, resulting in environmental and odor pollution, and must be managed to avoid their impact. This work aims to study the emission of VOCs utilizing TD-GC/MS and its relationship with changes in physico-chemical (moisture, pH, proteins, among others) and biological (bacteria and fungi using Illumina MiSeq) parameters under three environmental conditions: open-air (outdoors), under-roof (indoors) and oxygen-free. The 8-month study results showed a gradual increase in odorous VOCs and microbial diversity, a product of chemical and biological transformation processes in the samples. A 30% increase in odorant compounds responsible for the unpleasant smell was observed, especially esters, aldehydes and hydrocarbons in samples stored in oxygen-free and Open-air conditions. Increases in VOCs over time were associated with changes in physico-chemical and biological parameters, as well as fluctuations in environmental variables (temperature, relative humidity, and precipitation). The results of this research allow establishing a relationship between storage conditions and the production of VOCs. In addition, recommendations for waste storage time are provided for the most common uses of apple pomace based on the physico-chemical parameters observed, in order to avoid the generation of odorous compounds. Of all storage methods analyzed, under-roof is the most adequate in practice. This study's findings are pertinent for managing agribusiness waste and its potential environmental pollution.

Fabricating a visibly colorimetric film via self-releasing of anthocyanins from distributed mulberry pomace particles in hydrophilic sodium carboxymethyl starch-based matrix to monitor meat freshness

A highly distinguishable indicator film was developed based on sodium carboxymethyl starch, κ-carrageenan, carboxylated cellulose nanocrystals and mulberry pomace particles (MPPs). As the content of MPPs increased from 0 % to 6 %, the tensile strength decreased from 11.71 MPa to 5.20 MPa, the elongation at break increased from 26.84 % to 43.76 %, respectively, and the haze increased from 34.12 % to 52.10 %. The films accurately exhibit a color change from purple to blue-green under alkaline conditions. The enhanced haze improved the visible resolution of the films during the color-changing process. The films with the size of 7.50 mm × 7.50 mm and 10.0 mm × 10.0 mm exhibited obvious color changes when the total volatile basic nitrogen reached 14.60 mg/100 g and 19.04 mg/100 g, respectively, which accurately indicated the quality of pork and fish. This study will offer a simplified path to improve both accurate sensitivity and distinguishability for smart films.

Brazilian native fruit pomace as a source of bioactive compounds on starch-based films: Antimicrobial activities and food simulator release

The bioactive compounds extraction from fruit pomace is an ecological alternative for these abundant and low-added-value by-products. This study aimed to evaluate the antimicrobial potential of pomace extracts from Brazilian native fruits (araçá, uvaia, guabiroba and butiá) and the effect on physicochemical, mechanical properties and the migration of antioxidants and phenolic compounds from starch-based films. The film with butiá extract had the lowest mechanical resistance (1.42 MPa) but the highest elongation (63 %). In comparison, uvaia extract had less impact on film mechanical properties (3.70 MPa and 58 %) compared to the other extracts. The extracts and films showed antimicrobial activity against Listeria monocytogenes, L. inoccua, B. cereus and S. aureu. Approximately 2 cm inhibition halo was noticed for the extracts, while films ranged from 0.33 to 1.46 cm inhibition halo. Films with guabiroba extract had the lowest antimicrobial activity (0.33 to 0.5 cm). The phenolic compounds were released from the film matrix in the first hour at 4 °C with maintenance in the stability. The fatty-food simulator showed a controlled release of antioxidant compounds, which can assist in controlling food oxidation. Brazilian native fruit has shown to be a viable alternative to isolate bioactive compounds and produce film packaging with antimicrobial and antioxidant activities.

Drying and rehydration kinetics of peeled and unpeeled green apple slices (Granny Smith cv)

In this work, the kinetics of drying and rehydration of green apple slices peeled and unpeeled (Granny Smith cv) were studied. The apple slices were dried at 50, 60, and 70 °C, and after that, rehydrated at ambient (T_a) and boiling temperature (T_b). The drying kinetics were adjusted with the Dincer and Dost model, giving a good fit. Effective diffusivity (D_eff) and the convective mass transfer coefficient (h_m) were also determined, both coefficients increase with drying temperature, being 1.25 × 10^-9 m² s^-1 and 9.53 × 10^-7 m² s^-1 the highest values obtained for the peeled apple slices respectively. Peleg and Weibull models were adjusted to the rehydration experimental data obtaining a good fit (R² > 0.99). D_eff values increase significantly with rehydration temperature but take similar values between peeled and unpeeled samples. Acidity, pH, moisture content, solid soluble content, and equivalent diameter were determined to compare the fresh apple slices with those after dehydration and the post-rehydration process. The apple slices rehydrated at boiling temperature better preserved the characteristics of fresh samples due to the short immersion times in water, no significant differences were observed between peeled and unpeeled apples. According to the results, it is convenient to dry the apple slices unpeeled at 70 °C and rehydrate them at T_b.

Providing Stability to High Internal Phase Emulsion Gels Using Brewery Industry By-Products as Stabilizers

The modern brewing industry generates high amounts of solid wastes containing biopolymers-proteins and polysaccharides-with interesting technological and functional properties. The novelty of this study was to use raw by-product from the brewing industry in the development of high internal phase emulsion (HIPE) gels. Thus, the influence of the emulsion's aqueous phase pH and the by-product's concentration on structural and physical stability of the emulsions was studied. The microstructure was analyzed using cryo-field emission scanning electron microscopy. To evaluate the rheological behavior, oscillatory tests (amplitude and frequency) and flow curves were conducted. Moreover, the physical stability of the emulsions and the color were also studied. The increase in by-product concentration and the pH of the aqueous phase allowed development of HIPE gels with homogeneously distributed oil droplets of regular size and polyhedral structure. The data from the rheology tests showed a more stable structure at higher pH and higher by-product concentration. This study widens the possibilities of valorizing the brewing industry's by-products as stabilizers when designing emulsions.