Avocado Waste Research Articles

Comprehensive Utilization of Avocado in Biorefinery: A Bibliometric and Co-Occurrence Approach 2003–2023

In recent years, the consumption of avocado, both fresh and processed, has experienced a significant worldwide increase due to its recognized nutritional value and beneficial health effects. However, this industrial processing generates a substantial amount of underutilized byproducts, primarily the peel and seed, leading to significant environmental and economic challenges. Fortunately, these residues are rich in bioactive phytochemicals, making their recovery an excellent opportunity to enhance the sustainability and profitability of the modern avocado industry. This bibliometric analysis utilizes data from the Scopus platform to explore the comprehensive utilization of avocado waste. By employing a biorefinery approach and computational tools, the study aims to identify and extract value-added compounds with potential applications in the food, pharmaceutical, chemical, and cosmetic industries. The results highlight that the most relevant research topics are currently focused on sustainable and comprehensive biotransformation of avocado byproducts. Additionally, there is a growing emphasis on methods for extracting valuable products, characterizing their properties, and identifying potentially exploitable active compounds. Furthermore, research is increasingly exploring the environmental and economic factors associated with new research advancements, such as emerging environmental regulations, certifications, substitutes, and technological applications. One key gap identified in recent research advancements is the lack of a sustainable diagnostic framework for avocado utilization processes in a cascade system (multiple high-value consumer products and by-products such as bioplastic). This suggests a crucial area for future research efforts.

Enhanced extraction of procyanidins from avocado processing residues by pulsed electric fields pre-treatment.

The waste generated by the global production of avocado (Persea americana Mill), which includes peels, seeds, and pulp, poses environmental challenges. The principles of circular economy offer a sustainable solution by valorizing this waste and transforming it into valuable products. This study investigates the potential of avocado by-products, particularly peels and seeds, as a source of procyanidins. Pulsed electric field (PEF) technology has been shown to increase the extraction yield of valuable compounds from food waste/losses. In our study, we optimized the PEF treatment of avocado peels and seeds for the extraction of procyanidins by using Box-Behnken designs with response surface methodology and desirability functions. The effects evaluated were the frequency (1,50,100 Hz), the electric field strength (0.8, 1.1, 1.5 kV/cm) and the number of pulses (100, 150, 200) for avocado peel, while for the avocado seeds were the frequency (50, 100, 150 Hz), the electric field (0.6, 0.7, 0.8 kV/cm) and the total operating time (1, 5, 10 s). Our study showed that the procyanidin content measured by HPLC-FLD significantly increased in PEF-pretreated avocado peel and seeds. The optimized treatment conditions include a frequency of 50 Hz, an electric field strength of 1.31 kV/cm, and 175 electric pulses for the avocado peels, resulting in a procyanidin content of 9798.32 ± 103.83 μg CE/g d.w. For avocado seeds, the optimal conditions include a frequency of 100 Hz, an electric field strength of 0.75 kV/cm, and total operating time of 5.5 s, resulting in a procyanidin content of 21103.12 ± 234.76 μg/g d.w. The precision and validity of the mathematical models confirmed the reliability of these optimal conditions. These results emphasize the potential of PEF technology for the extraction of procyanidin from avocado waste and contribute to environmentally friendly extraction techniques in the food industry.

Nanoporous carbons from hydrothermally pre-treated avocado waste: experimental design, hydrogen storage behavior, and energy distribution analysis

AbstractAvocado waste, which includes the peel and seed, is a promising biomass source for highly porous materials crucial to establishing an economical and efficient hydrogen economy. Hydrothermally pre-treated avocado waste was explored as a precursor for biocarbon optimized for hydrogen storage, employing the design of experiment to vary activation temperature and impregnation ratio. The resulting optimized biocarbon, synthesized at 800 °C with a 1:3 impregnation ratio, exhibited appreciable hydrogen uptake at 77 K and 1 bar, surpassing some reported literature values. Notably, the optimized biocarbon (AC200), hydrothermally pretreated at 200 °C, demonstrated a remarkable 3.07 wt% hydrogen uptake, attributed to its narrower micropores facilitating extensive adsorption. The study employed a modified Langmuir model incorporating homotattic patch approximation for a universal isotherm model, providing insights into the surface characteristics of the optimized biocarbon in terms of adsorption site availability and energy distribution. The modeling offers insight into the heterogeneous surface characteristics, specifically regarding the availability of adsorption sites, elucidating the distinct behavior exhibited by each optimized biocarbon.

Production of trans-fat-free margarine prepared using catfish oil and palm stearin with the addition of avocado waste oil for tocopherol enrichment

Catfish oil (CFO) is rich in unsaturated fatty acids (UFA) which are potentially produced into margarine through the blending method with palm stearin (PS) addition. The high UFA content of CFO causes margarine to be susceptible to oxidative damage, which can also trigger the formation of trans fatty acids (TFA). An antioxidant compound in the form of avocado waste oil (AWO) that contains tocopherol is added during margarine production to inhibit oxidative damage and TFA formation in the final product. Thus, the temperature and duration of CFO extraction, avocado peel and seed ratio of AWO extraction, and CFO:PS:AWO ratio of margarine production were analyzed for their effect on CFO, AWO, and margarine characteristics. This study was conducted by several stages; CFO extraction with temperature (50, 70 and 90oC) and duration (1 and 2 hrs) treatment, AWO extraction with avocado peel and seed ratio treatment (100:0, 75:25, 50:50, 25:75, 0:100), and margarine production with CFO:PS:AWO ratio treatment (41:40:0, 36:40:5, 31:40:10, 26:40:15, 21:40:20). The results showed that the increasing extraction temperature and duration caused the decrease of CFO hydrolytic-oxidative stability. The best CFO extraction treatment was 50oC and 1 hr of extraction. The increasing avocado peel ratio in AWO extraction led to the increase of AWO antioxidant potential. The best AWO extraction treatment was the ratio of peel:seed = 75:25. The addition of AWO in margarine production for tocopherol enrichment was proven to suppress oxidative damage and TFA formation. The best margarine production treatment was the 3rd formulation (10% of AWO) with UFA-rich and trans-fat-free margarine characteristics. It was selected as the most preferred color, taste and flavor of margarine. These studies’ results are beneficial for the product development of UFA-rich and transfat-free margarine with good oxidative stability prepared using freshwater fish oil and plant byproduct oil.

Special Issue “Pretreatment and Bioconversion of Crop Residues II”—Introduction to the Collection

Bioconversion in biorefineries is a way to valorize residues from agriculture and food processing. Pretreatment is an important step in the bioconversion of lignocellulosic materials, including crop residues. This Special Issue includes nine articles on several pretreatment and bioconversion approaches applied to different agricultural residues and food-processing by-products. The materials addressed in this collection cover straw from wheat, rye, and miscanthus, olive tree pruning residue, almond shells and husks, avocado waste, sweet sorghum bagasse, soybean meal, and residues of non-edible oilseeds.

How to reduce waste using black soldier fly larvae and produce a high-quality product

Abstract With the growing human population the demand for protein is rising and waste production is increasing. Insects can provide a sustainable solution for both problems and produce food (protein and fat) from waste. Our study tested the ability of the black soldier fly (BSF) to reduce agricultural waste and produce a high-value product rich in unsaturated fatty acids. Initially, we tested the diet limitations of the larvae. We tested the composition of the agricultural wastes (brewery and avocado wastes) and the ability of the larvae to grow on them. A mixed diet based on brewery and avocado wastes was composed to increase larval weight and improve their fatty acid composition. The larvae were limited by the protein and water content of the diet (7% and 70%, respectively). The mixed diet that met the requirements of a minimal ratio of protein (7%) and optimal water content (70%), did not improve larval weight but increased the unsaturated fatty acid content. Therefore, using BSF larvae to reduce waste and produce protein is feasible; however, the end product should be considered when composing their diet from a waste mixture.

Sustainable Electricity Production Using Avocado Waste

Agroindustry waste has exponentially increased in recent years, generating economic losses and environmental problems. In addition, new ways to generate sustainable alternative electrical energy are currently being sought to satisfy energy demand. This investigation proposes using avocado waste as fuel for electricity generation in single-chamber MFCs. The avocado waste initially operated with an ambient temperature (22.4 ± 0.01 °C), DO of 2.54 ± 0.01 mg/L, TDS of 1358 ± 1 mg/L and COD of 1487.25 ± 0.01 mg/L. This research managed to generate its maximum voltage (0.861 ± 0.241 V) and current (3.781 ± 0.667 mA) on the fourteenth day, operating at an optimal pH of 7.386 ± 0.147, all with 126.032 ± 8.888 mS/cm of electrical conductivity in the substrate. An internal resistance of 67.683 ± 2.456 Ω was found on day 14 with a PD of 365.16 ± 9.88 mW/cm2 for a CD of 5.744 A/cm2. Micrographs show the formation of porous biofilms on both the anodic and cathodic electrodes. This study gives preliminary results of using avocado waste as fuel, which can provide outstanding solutions to agro-industrial companies dedicated to selling this fruit.

Avocado leaf‐waste management: drying technology and quality of leaf herbal teas of different varieties cultivated in the Mediterranean area

SummaryAvocado production is globally increasing, and wastes and by‐products are becoming an emergent problem for its sustainability. The research aims to valorise the avocado waste leaves, giving them new challenges and opportunities in the herbal tea sector. In this regard, leaves of different avocado varieties cultivated in the Mediterranean area and different drying technologies were considered for the preparation of herbal teas; chemical and sensory analyses have been carried out. The results demonstrated differences in the composition, antioxidant activity, aroma volatiles, sensory features, and thus on the consumers' acceptability of the avocado herbal teas in relation to the variety and the drying technology. Herbal teas prepared with microwave‐dried leaves of Fuerte and Bacon varieties were the most appreciated by consumers for their sweet taste and anise‐like odour. The data showed the possibility of using avocado leaf waste for new herbal teas, evidencing the influence of the drying technology and variety on the functional and sensory features of the developed product. In this context, the approach here applied resulted fundamental to orientate the development of new sustainable and healthy herbal tea that meets consumers' demands.

Equation-Oriented Modeling and Optimization of a Biorefinery Based on Avocado Waste

Due to the growth in the consumption of avocado in recent years, the amount of waste caused by avocado peel and seed has increased. Avocado waste can be transformed into valuable products such as energy, biofuels, and biological products using integrated processes in a biorefinery. This paper considers the detailed modeling, simulation, and optimization of a biorefinery for the production of phenolic compounds, bioethanol, biological xylitol, syngas, and electrical power from avocado seed and peel, using Aspen Plus in equation-oriented mode as a process simulation tool. For a biorefinery in nominal conditions, it is possible to achieve a gross profit of approximately 30×106 USD/year for capital costs of USD 31.4×106, while the combined effect of process optimization and heat integration allows reaching a gross profit of 37×106 USD/year for capital costs of USD 30.7×106. These results of the optimized plant show its potential to take advantage of avocado seed and peel in a profitable and sustainable way. This detailed equation-based model paves the way for superstructure optimization of a biorefinery for avocado waste processing.

Valorization of avocado peels by conventional extraction and hydrothermal carbonization for cosmeceutical applications

Avocado peels (APs) are an agro-industrial non-edible residue from avocado processing industries that lack commercially valuable applications despite their content of bioactive molecules. This work investigates for the first time the combined use of conventional extraction with hydrothermal carbonization (HTC) as a new strategy to maximize the bioactive fractions obtained from APs for potential cosmeceutical applications. APs were extracted by maceration, while the extracted biomass was subjected to HTC at 200, 250, and 300 °C. The ethanolic extract (EEPA), liquid phases (LBOs), and heavy bio-oils (HBOs) were characterized by FTIR, and their content of total phenol, hydroxycinnamic acids, flavonoids, and proanthocyanidins were further determined. The antioxidant properties of all fractions and their effects on tyrosinase and elastase activities were spectrophotometrically analyzed, whereas the most promising fractions were examined by GC-MS. LBOs were rich in total phenols, hydroxycinnamic acids, and flavonoids, whereas EEPA showed the highest content of proanthocyanidins. EEPA and LBOs exhibited the highest antioxidant ability. In contrast, HBOs had significant inhibitory effects on tyrosinase and elastase activities, higher than those of kojic acid and epigallocatechin gallate, used in the cosmeceutical industry to counteract hyperpigmentation and skin flaccidity, respectively. Esters (42 %) were the dominant molecules identified in EEPA, while phenols prevailed in LBO 250 °C (45 %) and HBO 250 °C (22%). These results open the way to apply conventional extraction and HTC as a new strategy for recycling avocado waste to develop sustainable cosmeceutical products.

Avocado Waste Biorefinery: Towards Sustainable Development

The increasing demand for avocado consumption has led to a vast generation of waste products. Despite the high nutritional value of avocados, the waste generated from their processing poses a significant environmental challenge. Therefore, the development of a sustainable approach to avocado waste management is a major concern. Biorefinery presents a promising approach to the valorization of avocado waste components, including the seed, peel, and pulp residues. This paper explores the potential of avocado waste biorefinery as a sustainable solution to produce bio-based products. Several approaches, including extraction, hydrolysis, fermentation, and biodegradation, to obtain valuable products such as starch, oil, fiber, and bioactive compounds for food or feed goods have been proposed. The review also highlights the approaches towards addressing challenges of energy security and climate change by utilizing avocado waste as a source to produce biofuels such as biogas, biodiesel, and bioethanol. In conclusion, the development of avocado waste biorefinery presents a promising avenue for sustainable development. This process can efficiently convert the avocado waste components into valuable bio-based products and clean energy sources, contributing to the attainment of a circular economy and a more sustainable future.

Alternatives for the Valorization of Avocado Waste Generated in the Different Links of the Value Chain Based on a Life-Cycle Analysis Approach

This work evaluates the sustainability of small-scale biorefineries as a potential enterprise alternative to be introduced in rural areas based on experimental and simulation data. Four scenarios were evaluated: the first scenario involves the production of guacamole, the second involves the production of animal feed, and the third and fourth scenarios involve the extraction of bioactive compounds and the production of avocado oil or animal feed, respectively. In addition, all scenarios produce biogas and fertilizer. Each of the scenarios were evaluated considering the technical, economic, environmental, and social aspects. As a main result, the first scenario showed the lowest operating and investment costs, as well as the lowest economic profitability (profit margin 35%). On the other hand, the third and fourth scenarios present the highest investment and operating expenses (OpEx USD 6.2 million per year and CapEx USD 1.0 million), but their profit margins are in the 60–70% range. Furthermore, a life-cycle assessment (LCA) was carried out and allows inferring that the transformer link presents the highest environmental impact of the entire value chain and that the carbon footprint for all scenarios ranges between 1.01–2.41 kg CO2 eq per kg avocado. Similarly, the social impact methodology shows that the proposed scenarios do not present any social risk. Thus, the biorefinery for animal feed, bioactive compounds, biogas, and fertilizer was selected as the best option to be implemented in Caldas.

Effects on Growth Performance Parameters, Carcass Traits, Meat Nutrimental Quality and Intramuscular Fatty Acid Profile of Rabbits Fed with Diets with Avocado Waste (Persea americana Mill)

The objective of this paper was to evaluate the effect of four levels (0%, 4.32%, 8.39% or 12.25%) of avocado waste (AW) included in the diets on productive performance, carcass characteristics and meat nutritional quality of fattening rabbits. For that, one hundred and twenty male rabbits (New Zealand × California; 945 ± 47 g initial body weight) were fed over 28 days, randomly distributed to one of the four treatments (T) (T1 = 0, T2 = 4.32, T3 = 8.39 and T4 = 12.25% AW as fed). The chemical and fatty acids profiles were evaluated in the Longissimus thoracis et lumborum (LTL) muscle. The rabbits fed with 8.39% of AW reported the best productive parameters (p < 0.05), the greater (p < 0.05) dissectible adipose tissue and higher polyunsaturated fatty acids (PUFAs) n-3 content (p < 0.05) than control meat. It is concluded that the inclusion of AW in the growing–finishing rabbit’s diet can modify the nutritional quality of the meat, reducing the n-6/n-3 ratio and the thrombogenic index.

A Review of Avocado Waste Valorization and Integrated Biorefinery System

A Review of Avocado Waste Valorization and Integrated Biorefinery System

Phenolic Compounds Profiling and Their Antioxidant Capacity in the Peel, Pulp, and Seed of Australian Grown Avocado.

Avocados (Persea americana M.) are highly valued fruits consumed worldwide, and there are numerous commercially available varieties on the market. However, the high demand for fruit also results in increased food waste. Thus, this study was conducted for comprehensive profiling of polyphenols of Hass, Reed, and Wurtz avocados obtained from the Australian local market. Ripe Hass peel recorded the highest TPC (77.85 mg GAE/g), TTC (148.98 mg CE/g), DPPH (71.03 mg AAE/g), FRAP (3.05 mg AAE/g), RPA (24.45 mg AAE/g), and ABTS (75.77 mg AAE/g) values; unripe Hass peel recorded the highest TFC (3.44 mg QE/g); and Wurtz peel recorded the highest TAC (35.02 mg AAE/g). Correlation analysis revealed that TPC and TTC were significantly correlated with the antioxidant capacity of the extracts. A total of 348 polyphenols were screened in the peel. A total of 134 compounds including 36 phenolic acids, 70 flavonoids, 11 lignans, 2 stilbenes, and another 15 polyphenols, were characterised through LC-ESI-QTOF-MS/MS, where the majority were from peels and seeds of samples extract. Overall, the hierarchical heat map revealed that there were a significant amount of polyphenols in peels and seeds. Epicatechin, kaempferol, and protocatechuic acid showed higher concentrations in Reed pulp. Wurtz peel contains a higher concentration of hydroxybenzoic acid. Our results showed that avocado wastes have a considerable amount of polyphenols, exhibiting antioxidant activities. Each sample has its unique value proposition based on its phenolic profile. This study may increase confidence in utilising by-products and encourage further investigation into avocado by-products as nutraceuticals.

The Impact of Replacement of Concentrates with Fermented Tithonia (Tithonia diversifolia) and Avocado Waste (Persea americana miller) in Fermented Sugarcane Shoots (Saccharum Officinarum) Based Rations on Consumption, Digestibility, and Production Perform

The Impact of Replacement of Concentrates with Fermented Tithonia (Tithonia diversifolia) and Avocado Waste (Persea americana miller) in Fermented Sugarcane Shoots (Saccharum Officinarum) Based Rations on Consumption, Digestibility, and Production Perform

Conical spouted bed combustor to obtain clean energy from avocado waste

The advantages of spouted bed technology for waste treatment are linked to the high excess of renewable biomass waste generated by the large worldwide consumption of avocado. Therefore, the applicability of avocado waste as fuel in a novel conical spouted bed combustor was investigated. The solid cyclic movement in this reactor innovatively promotes better mass and heat transfer, as well as better energy exploitation of the waste. Local heat transfer coefficients were experimentally determined in the beds of avocado waste in the combustor to assess their heat transfer and determine their value as biofuels. The combustion of the avocado beds in the spouted bed regime was performed at 300–600 °C in a conical reactor at the minimum spouting velocity. The exhaust gas evolution was monitored over time, and the emission ratios were calculated. The combustion efficiencies of avocado seeds, skin, and their binary mixtures, determined from flue gas concentrations, were compared, and the effects of temperature and bed composition on combustion efficiency were analyzed.

Bioelectricity through microbial fuel cells using avocado waste

The dumping of organic waste in the areas surrounding food supply centers and the excessive use of fossil fuels for energy generation have generated major pollution problems worldwide. One of the novel solutions is the use of organic waste for electricity generation through the use of microbial fuel cell technology. In this research, low-cost, laboratory-scale, double-chamber microbial fuel cells were fabricated using zinc and copper as electrodes and avocado waste as fuel. Current and voltage values of 3.7326 ± 0.05568 mA and 0.74 ± 0.02121 V were achieved on the seventh day, with an optimum operating pH of 5.98 ± 0.16 and a maximum electrical conductivity of 94.46 ± 5.12 mS/cm. The cells showed a very low operating resistance of 71.480 Ω, indicating the good electrical conductivity of the electrodes. Likewise, a power density of 566.80 ± 13.48 mW/cm2 at a current density of 5.165 A/cm2 was generated. This research provides an eco-friendly solution to farmers and companies dedicated to the export and import of this fruit because it shows the benefits of using their own waste for the generation of electricity, reducing costs.

Effect of biopolymer coatings made of zein nanoparticles and ε-polylysine as postharvest treatments on the shelf-life of avocados (Persea americana Mill. Cv. Hass)

Avocados (Persea americana) are a popular fruit produced and consumed all around the world. Due to their climacteric nature, they are predisposed to rapid loss of moisture and firmness after harvest and prior to sale. The prevalence of the fungal phytopathogen Colletotrichum spp. Exacerbates the rate of decay by causing anthracnose, resulting in relatively short shelf-lives, increased waste, and economic losses. The objective of this study was to assess the effect of coatings made of zein nanoparticles (ZNP), zein and ε-polylysine nanoparticles (ZPL), zein solution (ZS), and ε-polylysine solution (PL) on the weight loss, respiration rate, firmness, color, and fungal decay of avocados compared to a control (C). By day 15 in ambient storage, control avocados had scarred surfaces, significant color change, overripe pulp, and clear signs of fungal decay. At this time, avocados treated with ZPL lost the least weight, 20.14%, compared to the control, 28.05%. The lowest respiration rates were seen in ZPL treatment with values of 107.83 mg of CO2/kg/h. The flesh of the ZPL- and ZNP- treated fruit remained firmer, 5.01 and 4.07 N, respectively, compared to the control, 3.67 N. For pulp color, ZPL-treated fruit showed the smallest color difference as measured by total color change, ΔE, 3.67 compared to the control, 15.45. At the conclusion of a 15-day Colletotrichum spp. inoculation study, ZPL treated avocados had the significantly lowest fungal severity score of 3.33, while ZNP-treated fruit and the control had scores of 4 and 4.7, respectively. The results of this project support biopolymeric coatings as a novel technique with the potential to extend shelf-life and reduce avocado waste both at retail and household levels to possibly mitigate economic losses.

Avocado Peels and Seeds: Processing Strategies for the Development of Highly Antioxidant Bioplastic Films.

The industrial processing of avocados annually generates more than 1.2 million tons of avocado peels (APs) and avocado seeds (ASs) that have great potential in the production of active bioplastics, although they have never been considered for this aim until now. Separately, the APs and ASs, as well as a combination of avocado peels and seeds (APSs), were evaluated here for the first time for the preparation of antioxidant films, with application in food packaging. Films were prepared by casting, after their processing by three different methods: (1) hydrolysis in acid media, (2) hydrolysis followed by plasticization, and (3) hydrolysis and plasticization followed by blending with pectin polymers in different proportions (25 and 50 wt %). The results indicate that the combination of hydrolysis, plasticization, and pectin blending is essential to obtain materials with competitive mechanical properties, optical clarity, excellent oxygen barrier properties, high antioxidant activity, biodegradability, and migration of components in TENAX suitable for food contact applications. In addition, the materials prepared with APSs are advantageous from the point of view of the industrial waste valorization, since the entire avocado wastes are used for the production of bioplastics, avoiding further separation processes for their valorization.