Almond Hulls Research Articles

Nutritional characteristics of almond hulls treated with sodium hydroxide and urea or supplemented with polyethylene glycol as an alternative feed resource for ruminant nutrition in Mediterranean area: in vitro study

Nutritional characteristics of almond hulls treated with sodium hydroxide and urea or supplemented with polyethylene glycol as an alternative feed resource for ruminant nutrition in Mediterranean area: in vitro study

Almond Hulls and Shells Extract Characterized as a High-Performance Eco-Friendly Antioxidant and Corrosion Inhibitor

Almond Hulls and Shells Extract Characterized as a High-Performance Eco-Friendly Antioxidant and Corrosion Inhibitor

The effects of almond hulls and soil amendments on soil nutrients and microbial community within mature almond orchards

The effects of almond hulls and soil amendments on soil nutrients and microbial community within mature almond orchards

Feeding almond hulls to light lambs: Effects on growth performance, digestive utilization and blood metabolites

The effects of including almond hulls (AH) in the concentrate fed to light lambs on animal performance, diet utilization, and blood metabolites. Three isonitrogenous and isoenergetic concentrates were formulated with either 0 (control), 6 (AH6) or 12 (AH12) g of AH per 100 g (fresh matter basis). Thirty Manchega breed lambs (15 males and 15 females; 12.3 ± 0.18 kg body weight (BW)) were distributed into six homogeneous groups according to BW (3 groups of each sex), which were randomly assigned within sex to each experimental concentrate. Lambs were fed concentrate and barley straw ad libitum until reaching about 23.0 kg BW. There were no differences (P ≥ 0.182) between groups in final BW, intake of concentrate and straw, and feed conversion rate. Average daily gain and digestibility of dry matter and crude protein tended (P < 0.10) to decrease by the AH inclusion in the concentrate. Lambs fed AH12 showed greater (P < 0.05) urinary losses than those fed the control concentrate (15.4 and 11.5 g per 100 g of N intake, respectively), despite the similar N intake in all groups. Feeding AH did not affect (P ≥ 0.213) blood concentrations of albumin, globulins, urea, creatinine, glucose, total bilirubin and cholesterol or blood activities of hepatic enzymes. The post-mortem analysis revealed no differences among groups in pH and total volatile fatty acids (VFA) concentrations in the rumen of lambs, but NH3-N concentrations were lower (P < 0.05) in the lambs fed the concentrates with AH. In addition, lambs fed AH12 diet had lower (P < 0.05) molar proportions of propionate and greater (P < 0.05) proportions of butyrate compared with lambs fed control and AH6 concentrate. In general, no concentrate x sex interactions were observed, and sex had no effect on the measured parameters except for some differences in ruminal VFA profile. In conclusion, AH can be included at in light lambs’ concentrate up to 12 g per 100 g of concentrate without impairing animal growth.

Organic soil amendment effects on soil hydrology in an almond orchard evaluated using time-lapse electrical resistivity tomography

Adding organic amendments to soils in orchards has been suggested as a climate-smart agricultural practice that can increase resilience to extremes such as drought. The benefits of adding almond hulls and shells to soil include releasing potassium into the soil, improving water infiltration, reducing soil water evaporation, and enhancing water-holding capacity. In this study, soil infiltration and root water uptake (RWU) patterns of almond trees in amended and control soil treatments were investigated. An almond orchard was mulched with a mixture of almond hulls and shells used as surface-applied organic matter amendments. The combined use of time-lapse electrical resistivity tomography (ERT), stem water potential (SWP) and leaf water potential (LWP) measurements were used to evaluate RWU, soil infiltration patterns, and tree water status at different times during the study. The results of the ERT showed that the RWU patterns for the almond trees are distinct between the amended and the control treatments after the irrigation was applied. Compared to the control treatment, the amended treatment allowed the soil to store more water. Regardless of treatment, the majority of RWU patterns were observed in the top 0.5–1 m root zone depth. Almond trees began to recover from stress, as indicated by the SWP and LWP values, four hours after the start of irrigation. In addition, this was demonstrated by the ERT measurements, which revealed the RWU activity four hours after the irrigation had been applied. This research reveals that time-lapse ERT surveys combined with soil and tree water status data can infer patterns of RWU in almond trees grown with organic soil amendments and under controlled conditions. Furthermore, it was concluded that using almond hulls and shells as organic matter amendments can help almond growers improve infiltration, making almond production more resilient to climate change-related extremes such as droughts.

Sustainable and Biomimetic Methodology for Extraction of High-Value-Added Compounds in Almond Hulls.

Almond trees are the most cultivated nut tree in the world. The production of almonds generates large amounts of by-products, much of which goes unused. Herein, this study aimed to develop a green chemistry approach to identify and extract potentially valuable compounds from almond by-products. Initially, a screening was performed with 10 different Natural Deep Eutectic Solvents (NADESs). The mixture lactic acid/glycerol, with a molar ratio 1:1 (1:50 plant material to NADES (w/v) with 20% v/v of water) was identified as the best extraction solvent for catechin, caffeoylquinic acid, and condensed tannins in almond hulls. Subsequently, a method was optimized by a Design of Experiment (DoE) protocol using a miniaturized extraction technique, Microwave-Assisted Extraction (MAE), in conjunction with the chosen NADESs. The optimal conditions were found to be 70 °C with 15 min irradiation time. The optimal extraction conditions determined by the DoE were confirmed experimentally and compared to methods already established in the literature. With these conditions, the extraction of metabolites was 2.4 times higher, according to the increase in total peak area, than the established literature methods used. Additionally, by applying the multiparameter Analytical Greenness Metric (AGREE) and Green Analytical Process Index (GAPI) metrics, it was possible to conclude that the developed method was greener than the established literature methods as it includes various principles of green analytical chemistry.

Chemical Composition and Nutritive Value of Almond Hulls from Two Almond Varieties and Influence of Including Almond Hulls in the Diet on In Vitro Ruminal Fermentation and Methane Production.

Almond hulls (AH) are frequently used in dairy ruminant feeding, but information on variability of their nutritive value and their potential effects on CH4 production is still scarce. The influence of almond variety (Guara vs. Soleta) on chemical composition and energy value of AH was investigated using 10 samples per variety collected in 2 consecutive years. Guara-AH had greater (p ≤ 0.015) ash, protein, and fat content, but lower (p ≤ 0.001) fiber than Soleta-AH. The metabolizable energy content estimated from chemical composition and in vitro gas production was 8.5% greater for Guara than for Soleta samples. Harvesting year significantly affected most of the chemical fractions. The in vitro ruminal fermentation of diets for dairy ruminants including increasing amounts of dried AH (8, 16 and 24% of the total diet; fresh matter basis) indicated that AH can be included up to 16% of the diet, partially substituting corn, wheat bran and sugar beet pulp without detrimental effects on in vitro volatile fatty acid (VFA) production. In contrast, when AH replaced alfalfa hay and corn, VFA production was reduced at all levels of AH inclusion. No antimethanogenic effects of AH were detected in the in vitro incubations.

Evaluation of Almond Hull and Shell Amendments across Organic Matter Management of Orchard Soils

Hulls and shells are an abundant by-product from almond production with potential as an organic matter amendment (OMA). A combination of incubation study and field research was conducted in 2019–2021 to evaluate the impacts of three practices in combination on orchard soils’ C and N cycling, including a 210-day period of laboratory incubation with hulls and shells, and field sampling of orchard soils with and without historic applications of green waste compost as an OMA; with hulls and shells and with and without off-ground harvest where orchard soils remain undisturbed year round. Hulls and shells increased microbial biomass carbon in the field study by 248 μg g−1 dry soil after one year (p &lt; 0.001) and during incubation, and increased cumulative respiration in soils with and without historic OMA (p &lt; 0.001). Historic OMA resulted in double the total soil organic carbon (SOC) and total nitrogen (TN) compared to soil without resulting in significantly higher respiration and N mineralization when amended with hulls and shells. The decomposition of hull and shell biomass following surface application progressed at similar rates in the laboratory and field (1.7 g kg−1 d−1 during incubation (R2 = 0.84) and 1.3 g kg−1 d−1 in the field trial (R2 = 0.91). Our results highlight the suitability of hulls and shells as a by-product source of OMA for improving soil health in orchards with historic OMA and transitioning to organic matter management.

Evaluation of the Genotoxicity of Almond Hull: Implications for Its Use as a Novel Food Ingredient.

Almond hull, a substantial byproduct comprising more than half of almond fresh weight, has recently gained attention due to its functionality and sustainability benefits. Despite heightened interest, information regarding its toxicity remains limited. In order to assess its genotoxic potential, we conducted Good Laboratory Practice-compliant in vitro and in vivo studies following Organization for Economic Co-operation and Development (OECD) guidelines. No evidence of toxicity or mutagenicity was observed in a bacterial reverse mutation assay using five tester strains, evaluating almond hull at concentrations up to 5 mg/plate, with or without metabolic activation. Almond hull did not induce chromosome structural damage in a chromosome aberration assay using Chinese hamster ovary cells, nor did it cause any spermatogonial chromosomal aberration in tested male BALB/c mice. To evaluate its ability to induce DNA damage in rodents, a combined micronucleus assay was conducted in KM mice of both sexes. Almond hull was administered at doses of 1250, 2500, and 5000 mg/kg/day via gavage once daily for 2 days. No adverse effects of almond hull were observed in the micronucleus assay. Our results indicate no evidence of the genotoxic potential of almond hull administered up to the maximum concentrations of 5 g/kg, as recommended by OECD guidelines.

Almond hull in lactation sows diet: impact on reproduction, nutrient digestibility, fecal score, milk content, and suckling piglet growth.

Almond hull in lactation sows diet: impact on reproduction, nutrient digestibility, fecal score, milk content, and suckling piglet growth.

Dietary inclusion of almond hull on growth performance, nutrient digestibility, faecal microbiome, faecal score, and noxious gas emissions in weaning pigs

Dietary inclusion of almond hull on growth performance, nutrient digestibility, faecal microbiome, faecal score, and noxious gas emissions in weaning pigs

Recent Innovations on the Reuse of Almond and Hazelnut By-Products: A Review

Nuts consumption has increased significantly in the last 10 years, especially driven by the stimulated awareness of their possible beneficial health effects. Increased nuts consumption is linked to an obvious accumulation of by-products and waste. With the view of the circular economy, the aim of this review is to analyse the recent and innovative approaches able to valorise the by-products derived from almonds and hazelnuts, two important nut products of the Italian scene, with historical and traditional importance. The most important solutions are concerned with reuse of almond hull, shell, skin, oil cake, and hazelnut shell; skin and oil cake are often considered waste or by-products. Many interesting implications in the feed and food sectors have been detected in the last ten years, aimed at designing innovative materials developed from by-products and extraction of bioactive molecules for different purposes. The perspective chosen to discuss the topic is related to the sustainability of these processes, in terms of both the environment and economy. The circular economy supports a zero-waste approach, which should not also be meant as a zero-cost process in terms of the level of technology that has been partially developed.

Green recovery of phenolic compounds from almond hull waste using ultrasound-assisted extraction: phenolics characterization and antimicrobial investigation.

The online version contains supplementary material available at 10.1007/s13197-024-05969-3.

Potential of utilizing almond hull extract for filamentous fungi production by submerged cultivation

AbstractAlmond hulls can be used as an inexpensive source of nutrients for producing fungi that can be used as nontraditional foods such as alternative protein, probiotics, and food ingredients. Nutrients were extracted from almond hulls using hot water and their utility in cultivating filamentous fungus Aspergillus awamori (A. awamori) in submerged cultivation was investigated using batch fermentation in flasks with passive aeration. The almond hulls extract supplied all the nutrients required for A. awamori growth. The uptake preference of various sugars was investigated and the growth kinetic parameters of A. awamori were determined. Utilization of sugars by A. awamori grown in almond hull extract proceeded sequentially with preference for glucose followed by sucrose, fructose, and then xylose. Compared to potato dextrose broth medium, the fungal biomass produced using almond hull extract as growth medium had higher protein (19.59%) and lower fat (1.50%) contents. The modified Gompertz model described the kinetics of A. awamori well with a lag phase of 0.18 days and a specific growth rate of 1.77 d−1.

Almond By-Products Substrates as Sustainable Amendments for Green Bean Cultivation.

Almond processing generates a high quantity of by-products, presenting the untapped potential for alternative applications and improved sustainability in production. This study aimed to evaluate whether the incorporation of almond by-products (hulls/shells) can improve the biochemical characteristics of green bean pods when used as an alternative to traditional growing media in green bean plants. Four substrates were prepared: the Control substrate (C): 70% peat + 30% perlite; substrate (AS): 70% peat + 30% shells; substrate (AH): 70% peat + 30% perlite + 1 cm hulls as mulch; substrate (MIX): 70% peat + 15% shells + 15% hulls. Plants were grown in each of these substrates and subjected to two irrigation levels, 100% and 50% of their water-holding capacity. Biochemical parameters (photosynthetic pigments, total phenolics, flavonoids, ortho-diphenols, soluble proteins, antioxidant capacity) and color were evaluated in the harvested pods. Results showed that pods from plants growing in AH substrate presented statistically significant higher values in their total phenolic content, while AS and MIX substrates did not reveal significant benefits. Summarily, this study highlights the potential of almond hulls as a promising medium for green bean cultivation, particularly when employed as mulch. Further research is recommended to gain a more comprehensive understanding of the application of almond by-products as natural fertilizers/mulch.

Almond hulls and shells as an alternative fiber source in limit-fed growing beef cattle diets.

Almond hulls and shells are a by-product of almond production that can be incorporated as a feed ingredient in beef cattle diets. Three experiments were conducted to determine the effects of hammermill screen size on almond hull and shell bulk density and inclusion of ground or non-ground almond hulls and shells in limit-fed growing diets on growth performance, diet digestibility, and ruminal fermentation characteristics of beef cattle. In experiment 1, almond hulls and shells were ground with a laboratory-scale hammermill using no screen, a 11.1-mm screen, a 19.1-mm screen, or a 25.4-mm screen. Each screen-size treatment was ground at three separate time points (n= 3 replications/treatment). Grinding almond hulls and shells with no screen increased bulk density by 111% and minimized proportions of fine particles; therefore, almond hulls and shells ground using no screen were included as a treatment in the following experiments. In experiment 2, 364 steers (initial body weight [BW]: 257± 20.7kg) were blocked by truckload (n = 4), stratified by BW, and assigned to pen within block. Pens were randomly assigned to 1 of 4 experimental diets (n= 10 pens/treatment). The control diet (CON) contained (DM basis) 39.5% dry-rolled corn, 7.5% supplement, 40% wet-corn gluten feed, and 13% prairie hay. Non-ground (13AH) or ground (13GAH) almond hulls and shells replaced prairie hay and were fed at 13% of diet DM or non-ground almond hulls and shells were fed at 26% of diet DM and replaced 13% prairie hay and 13% dry-rolled corn (26AH). Diets were limit-fed at 2.2% of BW daily (DM basis) for 56 d. Overall average daily gains (ADG) were greater (P ≤ 0.05) for CON, 13AH, and 13GAH compared with 26AH. In addition, ADG from days 14 to 56 were greater (P= 0.03) for 13GAH and tended to be greater (P = 0.09) for 13AH compared with CON. Experiment 3 was a 4 × 4 replicated Latin square in which 8 ruminally cannulated heifers (initial BW = 378 ± 44.0kg) were fed diets from experiment 2. Apparent dry matter digestibility did not differ (P = 0.21) among treatments. Total ruminal volatile fatty acid concentrations were greater (P ≤ 0.03) for 13GAH and 13AH compared with 26AH and tended (P = 0.06) to be greater for 13GAH compared with CON. Overall, almond hulls and shells can be utilized as an alternative to prairie hay in limit-fed growing diets without negatively influencing rates of gain or diet digestibility.

Effect of Dietary Almond Hull on Growth Performance, Nutrient Digestibility, Organ Weight, Caecum Microbial Counts, and Noxious Gas Emission in Broilers.

Effect of Dietary Almond Hull on Growth Performance, Nutrient Digestibility, Organ Weight, Caecum Microbial Counts, and Noxious Gas Emission in Broilers.

Effect of torrefaction pretreatment on combustion behaviour of different agricultural wastes

In this study, which was carried out to investigate the effect of the torrefaction process on the combustion behaviour of agricultural wastes, almond hulls and shells, olive seeds and corn stalks were used. The samples, dried in a laboratory atmosphere, were torrified at 300 5ºC for 41 minutes. The change in fuel properties was determined by making proximate analyses of the solid product obtained after the process and compared with the raw sample. The effects of the torrefaction process on the combustion behaviour of agricultural wastes of different structures were investigated by burning the 1 0.15 g weighted raw and torrefied samples at 700ºC furnace initial temperature in a fixed bed system. Biochars containing higher fixed carbon were obtained with the torrefaction process applied to agricultural waste, and it was determined that this caused biochars to burn more efficiently and for a longer time than raw biomass. As a result, it was determined that biochar with better properties was produced by the torrefaction process applied to agricultural wastes and it was suitable for burning in solid fuel combustion systems. Thus, biochar obtained will both contribute to the country's economy and add value to agricultural wastes that cause problems during storage, transportation, loading into the burning system, and combustion.

Effect of dietary almond hull on growth performance, nutrient digestibility, fecal microbial, fecal score, and noxious gas emission in growing pigs

In a 42-day study, 195 growing pigs (Landrace × Yorkshire × Duroc) weighing 23.83 ± 1.95 kg were randomly divided into three treatments, each with 13 replicates and 5 pigs (3 barrows and 2 gilts) per pen. The treatments were control (CON)—basal diet, and basal diet with 3% and 6% almond hull as treatment (TRT) 1 and 2, respectively. The results show a significant increase ( p &lt; 0.05) in average daily gain (ADG) and average daily feed intake (ADFI) for both treatment 1 and treatment 2 by week 6 when compared to the control group. This improvement in ADG and ADFI exhibits a consistent trend ( p &lt; 0.10) throughout the overall trial period in comparison to the control group. Additionally, there is a tendency for enhanced gain-to-feed ratio (G:F) at the end of week 6 ( p &lt; 0.10) in comparison to the control group and remained constant ( p &gt; 0.05). No significant impact ( p &gt; 0.05) on nutrient digestibility and fecal microbiota was observed. However, NH3 gas showed a tendency to decrease ( p &lt; 0.10). Results suggested that almond hulls could improve growth and reduce ammonia gas without adverse effects on digestion, microbiota, and fecal score.

Green Strategies for Recovery of Bioactive Phenolic Compounds from Agro-Industrial Wastes (Pomegranate Peels, Almond Hulls, and Elderberry Pomace) Using Natural Deep Eutectic Solvents

Green Strategies for Recovery of Bioactive Phenolic Compounds from Agro-Industrial Wastes (Pomegranate Peels, Almond Hulls, and Elderberry Pomace) Using Natural Deep Eutectic Solvents