Abstract
As the global almond industry expands rapidly, large quantities of by-products are generated during processing (such as green hulls, shells, and skins), which are rich in functional constituents including polyphenols, flavonoids, dietary fibers, and volatile aroma compounds. This review summarizes the compositional characteristics and extraction technologies of these by-products, while elucidating their potential applications in food and biomaterials, with a specific focus on their antioxidant properties, bioactivities, and structural features. Furthermore, in light of recent research advances, the review further discusses poor stability, low bioavailability, challenges in processing compatibility, and other problems, proposing enhancement strategies such as nano-delivery, structural modification, and combined utilization.
Publication Date
9-20-2026
First Page
227
Last Page
233
DOI
10.13652/j.spjx.1003.5788.2025.80858
Recommended Citation
Jingyi, Xie; Wanqing, Wang; Xinyi, Wang; Chunle, Yuan; Yuna, Li; and Wei, Hua
(2026)
"Functional components and food application progress of almond by-products,"
Food and Machinery: Vol. 42:
Iss.
8, Article 28.
DOI: 10.13652/j.spjx.1003.5788.2025.80858
Available at:
https://www.ifoodmm.cn/journal/vol42/iss8/28
References
[1] Fornés Comas J,Socias I Company R,Alonso Segura J M.Shell hardness in almond:cracking load and kernel percentage [J].Scientia Horticulturae,2019,245:7-11.
[2] Esfahlan A J,Jamei R,Esfahlan R J.The importance of almond (Prunus amygdalus L.) and its by-products [J].Food Chemistry,2010,120(2):349-360.
[3] Calle A,Aparicio-Durán L,Batlle I,et al.Review of agronomic and kernel quality traits of 273 almond cultivars [J].Genetic Resources and Crop Evolution,2025,72(4):3 783-3 828.
[4] Calderón-Pavón A,García-Tejero I F,Noguera-Artiaga L,et al.Linking almond yield and quality to the production system and irrigation strategy considering the plantation age in a mediterranean semiarid environment [J].Agronomy,2025,15(6):1 448.
[5] Silva V,Oliveira I,Pereira J A,et al.Almond by-products:a comprehensive review of composition,bioactivities,and influencing factors [J].Foods,2025,14(6):1 042.
[6] Cao L,El Mashad H M,Pan Z L,et al.Production of filamentous fungal biomass (Aspergillus awamori) in pellet form from almond hull extract [J].Food and Bioprocess Technology,2025,18(10):8 735-8 750.
[7] Pascuzzi S,Santoro F.Analysis of the almond harvesting and hulling mechanization process:a case study [J].Agriculture,2017,7(12):100.
[8] Yao Y Y,Liu J E,Miao Q M,et al.Evaluation of the genotoxicity of almond hull:implications for its use as a novel food ingredient [J].Foods,2024,13(9):1 404.
[9] Liu J E,Yao Y Y,Cheng Y L,et al.Acute oral toxicity evaluation of almond hull powders in BALB/c mice [J].Foods,2023,12(22):4 111.
[10] Li X M,Liu Y N,Hao J X,et al.Study of almond shell characteristics [J].Materials,2018,11(9):1 782.
[11] Valdés A,Mondragon G,Garrigós M C,et al.Microwave-assisted extraction of cellulose nanocrystals from almond (Prunus amygdalus) shell waste [J].Frontiers in Nutrition,2023,9:1071754.
[12] Ledbetter C A.Shell cracking strength in almond (Prunus dulcis [Mill.] D.A.Webb.) and its implication in uses as a value-added product [J].Bioresource Technology,2008,99(13):5 567-5 573.
[13] Seeler D P,Kerr W L,Kerrihard A L,et al.Statistical modelling of sensory,physical,and chemical changes in almonds during prolonged storage at different conditions:Effect of shelling on shelf life [J].Postharvest Biology and Technology,2024,209:112713.
[14] Oliver Chen C Y,Milbury P E,Blumberg J B.Polyphenols in almond skins after blanching modulate plasma biomarkers of oxidative stress in healthy humans [J].Antioxidants,2019,8(4):95.
[15] Valdés A,Vidal L,Beltrán A,et al.Microwave-assisted extraction of phenolic compounds from almond skin byproducts (Prunus amygdalus):a multivariate analysis approach [J].Journal of Agricultural and Food Chemistry,2015,63(22):5 395-5 402.
[16] Tungmunnithum D,Abid M,Elamrani A,et al.Almond skin extracts and chlorogenic acid delay chronological aging and enhanced oxidative stress response in yeast [J].Life,2020,10(6):80.
[17] 戴昊昕,杨大伟.显齿蛇葡萄叶提取物黄酮化合物鉴定及抗氧化活性研究 [J].食品与机械,2026,42(1):139-144.Dai H X,Yang D W.Flavonoid identification and antioxidant activity of Ampelopsis grossedentata leaf extract [J].Food & Machinery,2026,42(1):139-144.
[18] Prgomet I,Gonçalves B,Domínguez-Perles R,et al.Irrigation deficit turns almond by-products into a valuable source of antimicrobial (poly)phenols [J].Industrial Crops and Products,2019,132:186-196.
[19] Charalabidis A,Sfouni M,Bergström C,et al.The biopharmaceutics classification system (BCS) and the biopharmaceutics drug disposition classification system (BDDCS):beyond guidelines [J].International Journal of Pharmaceutics,2019,566:264-281.
[20] Murathan Z T,Kaya A,Erbil N,et al.Comparison of bioactive components,antimicrobial and antimutagenic features of organically and conventionally grown almond hulls [J].Erwerbs-Obstbau,2020,62(4):463-472.
[21] Qureshi M N,Numonov S,Aisa H A.Chemical and pharmacological evaluation of hulls of prunus dulcis nuts [J].International Journal of Analytical Chemistry,2019,2 019(1):5861692.
[22] Sang S M,Lapsley K,Jeong W S,et al.Antioxidative phenolic compounds isolated from almond skins (Prunus amygdalus Batsch) [J].Journal of Agricultural and Food Chemistry,2002,50(8):2 459-2 463.
[23] Tlili N,Kirkan B,Sarikurkcu C.LC-ESI-MS/MS characterization,antioxidant power and inhibitory effects on α-amylase and tyrosinase of bioactive compounds from hulls of Amygdalus communis:the influence of the extracting solvents [J].Industrial Crops and Products,2019,128:147-152.
[24] Ben Khadher T,Sassi-Aydi S,Aydi S,et al.Phytochemical profiling and biological potential of Prunus dulcis shell extracts [J].Plants,2023,12(14):2 733.
[25] Bolling B W,Dolnikowski G,Blumberg J B,et al.Quantification of almond skin polyphenols by liquid chromatography-mass spectrometry [J].Journal of Food Science,2009,74(4):C326-C332.
[26] An J,Liu J E,Liang Y Y,et al.Characterization,bioavailability and protective effects of phenolic-rich extracts from almond hulls against pro-oxidant induced toxicity in Caco-2 cells [J].Food Chemistry,2020,322:126742.
[27] Fabroni S,Trovato A,Ballistreri G,et al.Almond [Prunus dulcis (mill.) DA Webb] processing residual hull as a new source of bioactive compounds:phytochemical composition,radical scavenging and antimicrobial activities of extracts from Italian cultivars ('tuono','pizzuta','romana') [J].Molecules,2023,28(2):605.
[28] Takeoka G R,Dao L T.Antioxidant constituents of almond [Prunus dulcis (Mill.) D.A.Webb] hulls [J].Journal of Agricultural and Food Chemistry,2003,51(2):496-501.
[29] 徐小锦,熊向源,高洪霞,等.蛋白质基复合纳米递送体系的构建策略与应用研究进展 [J].食品与机械,2026,42(1):202-212.Xu X J,Xiong X Y,Gao H X,et al.Research progress on construction strategies and applications of protein-based composite nanodelivery systems [J].Food & Machinery,2026,42(1):202-212.
[30] 尤婷婷,马永强,赵若冰,等.叶黄素纳米脂质体的制备及体外消化特性研究 [J].食品与机械,2025,41(12):28-36.You T T,Ma Y Q,Zhao R B,et al.Preparation and in vitro digestion characteristics of lutein nanoliposomes [J].Food & Machinery,2025,41(12):28-36.
[31] Qin K M,Sun X Y,Liu J M,et al.A rosmarinic acid-fish skin protein-chitosan hybrid nano-delivery system with excellent sustained-release and antioxidant performances [J].Food Chemistry,2025,491:145316.
[32] Cui Q C,Song X X,Li M S,et al.Obtention,interaction,and characterization of the soy protein isolate-glycyrrhizin nano complex for encapsulating naringenin [J].Food Hydrocolloids,2023,145:109110.
[33] Dai Z J,Yin W T,Li J H,et al.Zein and trimethyl chitosan-based core-shell nanoparticles for quercetin oral delivery to enhance absorption by paracellular pathway in obesity mice [J].Biomaterials Research,2025,29:193.
[34] Wei Y J,Xiao C G,Lu W J,et al.Fabrication,characterization and in vitro controlled-releasing of naringin nano-particles encapsulated by chitosan-carboxymethyl konjac glucomannan[J].LWT-Food Science and Technology,2024,200:116191.
[35] Wang F,Zhao C Y,Tian G F,et al.Naringin alleviates atherosclerosis in ApoE-/- mice by regulating cholesterol metabolism involved in gut microbiota remodeling [J].Journal of Agricultural and Food Chemistry,2020,68(45):12 651-12 660.
[36] Pan Y K,Li R,Jing N N,et al.Isorhamnetin-lignin nanoparticles:green preparation,characterization,remarkable bioavailability and long-lasting bioactivity in vivo [J].Food Bioscience,2025,69:106931.
[37] Wu L P,Huang W S,Peng K J,et al.Enhancing the stability,BBB permeability and neuroprotective activity of verbascoside in vitro using lipid nanocapsules in combination with menthol[J].Food Chemistry,2023,414:135682.
[38] Barahuie F,Dorniani D,Saifullah B,et al.Impacts of designed vanillic acid-polymer-magnetic iron oxide nanocomposite on breast cancer cells [J].Heliyon,2024,10(12):e32863.
[39] Wang X Y,Tang H,Chen M J,et al.Bigels as capsaicin and Gallic acid co-delivery systems:controlled release and enhanced bioavailability [J].Journal of Food Science,2025,90(3):e70147.
[40] Kahlaoui M,Dalla Vecchia S B,Giovine F,et al.Characterization of polyphenolic compounds extracted from different varieties of almond hulls (Prunus dulcis L.) [J].Antioxidants,2019,8(12):647-663.
[41] Ma X,Zhou X Y,Qiang Q Q,et al.Ultrasound-assisted extraction and preliminary purification of proanthocyanidins and chlorogenic acid from almond (Prunus dulcis) skin [J].Journal of Separation Science,2014,37(14):1 834-1 841.
[42] Clifford M N,Kerimi A,Williamson G.Bioavailability and metabolism of chlorogenic acids (acyl-quinic acids) in humans[J].Comprehensive Reviews in Food Science and Food Safety,2020,19(4):1 299-1 352.
[43] Wu M S,Brown A C.Applications of catechins in the treatment of bacterial infections [J].Pathogens,2021,10(5):546.
[44] Deuchande T,Fundo J F,Pintado M E,et al.Protocatechuic acid as an inhibitor of lipid oxidation in meat [J].Meat Science,2024,213:109519.
[45] Yao Y Y,Liu J E,Miao Q M,et al.Inhibition and effect of almond hull extract on activities of α-amylase and α-glucosidase,and postprandial glucose in normal SD rats [J].Journal of Functional Foods,2024,123:106624.
[46] D'Arcangelo S,Santonocito D,Messina L,et al.Almond hull extract valorization:from waste to food recovery to counteract Staphylococcus aureus and Escherichia coli in formation and mature biofilm [J].Foods,2024,13(23):3 834.
[47] Wang F J,Yuan H T,Shen J,et al.Nanozymes with broad-spectrum scavenging of reactive oxygen species (ROS) alleviate inflammation in acute liver injury [J].ACS Materials Letters,2024,6(4):1 304-1 316.
[48] Picerno P,Crascì L,Iannece P,et al.A green bioactive by-product almond skin functional extract for developing nutraceutical formulations with potential antimetabolic activity[J].Molecules,2023,28(23):7 913.
[49] 中华人民共和国国家卫生健康委员会,国家市场监督管理总局.GB 2760—2024 食品安全国家标准 食品添加剂使用标准 [S].北京:中国标准出版社,2025:2.General Administration of Quality Supervision,Inspection and Quarantine of the People's Republic of China.GB 2760—2024 National Food Safety Standards Standards for the use of food additives [S].Beijing:Standards Press of China,2025:2.
[50] Oliveira I,Marinho B,Szymanowska U,et al.Chemical and sensory properties of waffles supplemented with almond skins[J].Molecules,2023,28(15):5 674.
[51] Garcia C,Dias M I,Henriques M H F,et al.Pterospartum tridentatum liqueur using spirits aged with almond shells:chemical characterization and phenolic profile [J].Molecules,2023,28(11):4 455.
[52] Vuono L F,Sicari V,Mincione A,et al.Reuse of almond skin to formulate a new gluten- and lactose-free bakery product [J].Foods,2024,13(23):3 796.
[53] 韩林学,张续,邱天,等.对羟基苯甲酸酯类防腐剂的环境和人体暴露研究进展 [J].环境化学,2023,42(8):2 563-2 575.Han L X,Zhang X,Qiu T,et al.Research progress in the study of environmental and human exposure to paraben preservatives[J].Environmental Chemistry,2023,42(8):2 563-2 575.
[54] Loizzo M R,Tundis R,Leporini M,et al.Almond (Prunus dulcis cv.casteltermini) skin confectionery by-products:new opportunity for the development of a functional blackberry (Rubus ulmifolius schott) jam [J].Antioxidants,2021,10(8):1 218.
[55] Dhankhar J,Yadav M,Kundu P,et al.Storage stability of almond paste fortified with almond skin as antioxidants [J].Journal of Food Processing and Preservation,2022,46(3):e16410.
[56] Schevey C T,Brewer M S.Effect of natural antioxidants and lipid model system on lipid oxidation [J].Journal of Food Quality,2015,38(1):40-52.
[57] 杜鹏.食品包装设计理论与美术创意应用研究 [J].食品与机械,2026,42(1):253-254.Du P.Research on food packaging design theory and application of artistic creativity [J].Food & Machinery,2026,42(1):253-254.
[58] Chen Z,Azizt,Sunh Y,et al.Advances and applications of cellulose bio-composites in biodegradable materials [J].Journal of Polymers and the Environment,2023,31(6):2 273-2 284.
[59] Martin-Perez L,Contreras C,Chiralt A,et al.Active polylactic acid (PLA) films incorporating almond peel extracts for food preservation [J].Molecules,2025,30(9):1 988.
[60] Selvamurugan T S,Balasubramanian P.Development of almond shell powder and palm kernel fibre-reinforced cardanol oil toughened epoxy resin hybrid composites:mechanical,wear,and antimicrobial properties [J].Biomass Conversion and Biorefinery,2024,14(20):26 509-26 519.
[61] VÁzquez-Loureiro P,Lestido-Cardama A,Sendón R,et al.Investigation of migrants from can coatings:occurrence in canned foodstuffs and exposure assessment [J].Food Packaging and Shelf Life,2023,40:101183.
[62] Valdés A,Garrigós M C,Jiménez A.Extraction and characterization of antioxidant compounds in almond (Prunus amygdalus) shell residues for food packaging applications [J].Membranes,2022,12(8):806.
