Proteine di frumento (Triticum spp.)

Descrizione

• Proteine vegetali derivate dal frumento, impiegate soprattutto come glutine vitale di frumento (vital wheat gluten), **proteine idrolizzate di frumento (**HWP — hydrolyzed wheat protein ) e, meno spesso, isolato proteico di frumento.

• Razionale funzionale: la rete glutinica (glutenine elastiche + gliadine estensibili) fornisce struttura, ritenzione di gas, film-forming e masticabilità in impasti e sistemi plant-based.

• Profilo sensoriale: cereale neutro–delicato; le HWP a basse dosi aggiungono umami e leggere note fermentate.

Valore calorico (per 100 g, polveri secche)

• Glutine vitale di frumento: ~360–380 kcal, proteine 70–80 g, carboidrati 10–15 g, grassi 4–8 g.

• HWP / isolati: in genere 360–390 kcal, proteine 80–90 g (dipende dal grado), grassi ≤3 g.

Principali sostanze contenute

• Proteine del glutine: glutenine (polimeriche, elasticità) e gliadine (monomeriche, viscoelasticità).

• Peptidi/amminoacidi (nelle HWP) con maggiore solubilità e attività superficiale.

• Minerali/vitamine: solo tracce (la lavorazione rimuove gran parte dei solidi non proteici).

Processo di produzione

• Macinazione → lavaggio dell’impasto per rimuovere l’amido → separazione del glutine, disidratazione, essiccazione → macinazione (glutine vitale).

• Idrolisi (enzimatica/acida) del glutine → HWP, quindi neutralizzazione, filtrazione e spray drying.

• Opzionali frazionamento/filtrazione per modulare peso molecolare/solubilità; instantizzazione/agglomerazione per migliorare disperdibilità.

• Controlli qualità: % proteine (Kjeldahl/Dumas), umidità, ceneri, granulometria/flussibilità, curva di solubilità (pH), cariche microbiche, micotossine (es. DON), metalli.

Proprietà sensoriali e tecnologiche

• Struttura e tenuta gas: crea reti elastiche per oven spring e crumb sviluppati.

• Gestione dell’acqua: aumenta assorbimento e tolleranza d’impasto; con ricetta adeguata migliora la resistenza al freeze–thaw.

• Emulsionante/schiumogene: più marcate con HWP (peptidi più piccoli, più attivi all’interfaccia).

• Heat set & film-forming: migliora legame e affettabilità in analoghi carne/ibridi e paste ripiene.

• Sensibilità a pH/sali/ossidoriduzione: la funzionalità varia con forza ionica e bilancio redox dell’impasto.

Impieghi alimentari

• Bakery: pane, panini, flatbread, pane ad alto tenore proteico, pasta/noodles (fermezza), sfogliati.

• Analoghi di carne ed estensori: seitan, sistemi patty/loaf; binder in insaccati cotti ove consentito.

• Snack/estrusione: migliora elasticità e struttura cellulare.

• Bevande/cucina: HWP per stabilità di schiuma, mouthfeel e umami in zuppe/salse (verificare i claim gluten-free).

Nutrizione e salute

• Alta densità proteica; profilo limitato in lisina → complementare con legumi/soia per copertura di amminoacidi essenziali.

• Fibre minime negli isolati/glutine; sodio intrinsecamente basso.

• Disturbi correlati al glutine: non idonee per celiachia o allergia al frumento; anche le HWP restano allergenic per i sensibilizzati.

Profilo dei grassi

• Grassi totali bassi; i lipidi residui sono soprattutto PUFA — grassi polinsaturi (es. linoleico n-6: potenzialmente benefici se bilanciati, più ossidabili) e MUFA — grassi monoinsaturi (es. oleico n-9: spesso neutri/favorevoli), con SFA — grassi saturi minimi (da moderare nella dieta complessiva). TFA — acidi grassi trans trascurabili; MCT — trigliceridi a media catena non significativi.

Qualità e specifiche (temi tipici)

• % proteine (s.s.), umidità/ceneri, gluten index o wet gluten, Alveografo/Estensografo (es. W, P/L), assorbimento acqua (Farinografo), solubilità (HWP), colore/odore.

• Microbiologia: basse cariche, patogeni assenti/25 g.

• Contaminanti: DON (deossinivalenolo) e metalli entro limiti.

Conservazione e shelf-life

• Conservare fresco/asciutto/ermetico, lontano da odori; shelf-life tipica 12–24 mesi per polveri a bassa aw.

• Impasti/miscele idratate: trattare come deperibili, ≤4 °C e uso secondo ricetta.

Allergeni e sicurezza

• Contiene allergene maggiore: frumento (glutine). Etichettatura obbligatoria nella maggior parte dei mercati.

• Rischio di cross-contact con altri allergeni in impianti misti: mantenere piani allergeni con CCP convalidati.

Funzioni INCI in cosmesi (ove applicabile)

• INCI: Hydrolyzed Wheat Protein, Wheat Gluten, Wheat Amino Acids.

• Ruoli: film-forming, skin conditioning, lieve umettanza, stabilizzazione di emulsioni (nel rispetto di limiti d’uso/sicurezza).

Troubleshooting

• Pane denso/basso volume: sotto-impasto o glutine debole → aumentare impasto/ossidanti (es. acido ascorbico), regolare idratazione, incrementare glutine vitale.

• Strappi/bassa estensibilità: rete troppo ossidata/stretta → ridurre tempo di impasto/ossidanti, usare agenti riducenti (es. L-cisteina ove consentita), aumentare riposi.

• Impasto appiccicoso/scarsa lavorabilità: iper-idratazione o sale basso → riequilibrare acqua/sale, raffreddare l’impasto, aggiungere grassi/emulsionanti.

• Burger sbriciolati (analoghi): alzare idratazione/leganti (amidi/fibre), incorporare olio emulsionato, ottimizzare coagulazione termica.

Sostenibilità e filiera

• Il frumento è ampiamente ruotato, a supporto della salute del suolo; GHG per unità di proteina inferiori rispetto a molte fonti animali.

• Operare sotto GMP/HACCP; gestire le acque verso target BOD/COD; usare pack riciclabili; verificare controllo micotossine a monte.

Etichettatura

• Indicare “vital wheat gluten”, “hydrolyzed wheat protein (HWP)” o “wheat protein isolate” secondo il caso; evidenziare l’allergene frumento/glutine.

• Claim proteici (es. “alto contenuto di proteine”) solo se i tenori rispettano la normativa.

Conclusione

Le proteine di frumento offrono struttura di riferimento per la panificazione e robusto binding/film-forming in cucina e negli analoghi carne. La scelta della forma (glutine vs HWP) e la messa a punto di idratazione, bilancio ossidoriduttivo, pH e sali consentono alto volume, buon morso e texture stabili con aroma pulito.

Mini-glossario

• HWP — hydrolyzed wheat protein: proteine di frumento idrolizzate, più solubili e attive all’interfaccia.

• WHC/OHC — water/oil-holding capacity: capacità di legare acqua/olio; guida resa, succosità e ritenzione di grasso.

• PUFA — grassi polinsaturi: potenzialmente benefici se bilanciati; più suscettibili a ossidazione.

• MUFA — grassi monoinsaturi: spesso neutri/favorevoli e relativamente stabili.

• SFA — grassi saturi: da moderare nella dieta complessiva; quota bassa qui.

• TFA — acidi grassi trans: trascurabili negli ingredienti non idrogenati.

• MCT — trigliceridi a media catena: non significativi nelle proteine di frumento.

• GMP/HACCP — good manufacturing practice / hazard analysis and critical control points: sistemi igienico–preventivi con punti critici convalidati.

• BOD/COD — domanda biochimica/chimica di ossigeno: indicatori dell’impatto dei reflui e dell’efficienza di trattamento.

Bibliografia__________________________________________________________________________

Johnson VA. Wheat protein. Basic Life Sci. 1976 Mar 1-7;8:371-85. doi: 10.1007/978-1-4684-2886-5_33. 

Abstract. Results from AID-supported Nebraska research to improve the nutritional quality of wheat indicate that substantial genetic variation for grain protein content exists in wheat. Experimental lines with 5% higher protein in their grain than ordinary varieties have been selected from a high-protein X high-protein cross. Genetic variablity for lysine in wheat grain is limited. The genetic component of total lysine variability among 12,6000 wheats in the USDA World Collection was only 0.5%. Genetic increases in lysine ranging from 0.4 to 0.7% lysine have been identified in selections from a high-lysine X high-lysine cross. Lysine per unit protein is negatively correlated with protein content. In contrast, lysine per unit weight of grain is positively correlated with protein content suggesting that increasing the protein content of wheat can effectively increase the amount of lysine in the grain. Seed fractionation studies have determined that high protein in whole wheat results mainly from increased protein content of the starchy endosperm. Lysine differences were detected both in the endosperm and nonendosperm fractions. A new productive high-protein hard winter wheat variety derived from Atlas-66, with genetic potential for 2% higher grain protein content was released to growers by the Agricultural Research Service, USDA and the Nebraska Agricultural Experiment Station in 1975.

Alomari DZ, Schierenbeck M, Alqudah AM, Alqahtani MD, Wagner S, Rolletschek H, Borisjuk L, Röder MS. Wheat Grains as a Sustainable Source of Protein for Health. Nutrients. 2023 Oct 17;15(20):4398. doi: 10.3390/nu15204398. 

Abstract. Protein deficiency is recognized among the major global health issues with an underestimation of its importance. Genetic biofortification is a cost-effective and sustainable strategy to overcome global protein malnutrition. This study was designed to focus on protein-dense grains of wheat (Triticum aestivum L.) and identify the genes governing grain protein content (GPC) that improve end-use quality and in turn human health. Genome-wide association was applied using the 90k iSELECT Infinium and 35k Affymetrix arrays with GPC quantified by using a proteomic-based technique in 369 wheat genotypes over three field-year trials. The results showed significant natural variation among bread wheat genotypes that led to detecting 54 significant quantitative trait nucleotides (QTNs) surpassing the false discovery rate (FDR) threshold. These QTNs showed contrasting effects on GPC ranging from -0.50 to +0.54% that can be used for protein content improvement. Further bioinformatics analyses reported that these QTNs are genomically linked with 35 candidate genes showing high expression during grain development. The putative candidate genes have functions in the binding, remobilization, or transport of protein. For instance, the promising QTN AX-94727470 on chromosome 6B increases GPC by +0.47% and is physically located inside the gene TraesCS6B02G384500 annotated as Trehalose 6-phosphate phosphatase (T6P), which can be employed to improve grain protein quality. Our findings are valuable for the enhancement of protein content and end-use quality in one of the major daily food resources that ultimately improve human nutrition.

Wang D, Li F, Cao S, Zhang K. Genomic and functional genomics analyses of gluten proteins and prospect for simultaneous improvement of end-use and health-related traits in wheat. Theor Appl Genet. 2020 May;133(5):1521-1539. doi: 10.1007/s00122-020-03557-5. 

Abstract. Recent genomic and functional genomics analyses have substantially improved the understanding on gluten proteins, which are important determinants of wheat grain quality traits. The new insights obtained and the availability of precise, versatile and high-throughput genome editing technologies will accelerate simultaneous improvement of wheat end-use and health-related traits. Being a major staple food crop in the world, wheat provides an indispensable source of dietary energy and nutrients to the human population. As worldwide population grows and living standards rise in both developed and developing countries, the demand for wheat with high quality attributes increases globally. However, efficient breeding of high-quality wheat depends on critically the knowledge on gluten proteins, which mainly include several families of prolamin proteins specifically accumulated in the endospermic tissues of grains. Although gluten proteins have been studied for many decades, efficient manipulation of these proteins for simultaneous enhancement of end-use and health-related traits has been difficult because of high complexities in their expression, function and genetic variation. However, recent genomic and functional genomics analyses have substantially improved the understanding on gluten proteins. Therefore, the main objective of this review is to summarize the genomic and functional genomics information obtained in the last 10 years on gluten protein chromosome loci and genes and the cis- and trans-factors regulating their expression in the grains, as well as the efforts in elucidating the involvement of gluten proteins in several wheat sensitivities affecting genetically susceptible human individuals. The new insights gathered, plus the availability of precise, versatile and high-throughput genome editing technologies, promise to speed up the concurrent improvement of wheat end-use and health-related traits and the development of high-quality cultivars for different consumption needs.

Yahata E, Maruyama-Funatsuki W, Nishio Z, Tabiki T, Takata K, Yamamoto Y, Tanida M, Saruyama H. Wheat cultivar-specific proteins in grain revealed by 2-DE and their application to cultivar identification of flour. Proteomics. 2005 Oct;5(15):3942-53. doi: 10.1002/pmic.200402103. 

Abstract. Wheat flour proteins were studied to identify the cultivar-specific proteins and use them to identify cultivars in flours. Proteins extracted from flours of Japanese wheat (cultivars Hokushin, Horoshirikomugi, Kitanokaori and Kachikei 33) and Canadian wheat (Canada Western Red Spring Wheat No. 1; 1CW) were analyzed by 2-DE with IEF gels over three pH ranges: pH 4-7, pH 5-8, and pH 6-11. This system enabled detection of more than 1600 protein spots. We recognized that among 50 protein spots showing cultivar-dependent qualitative changes, 25 proteins were wheat cultivar specific. These 50 protein spots were analyzed by N-terminal Edman degradation microsequencing and MALDI-TOF-MS; 21 protein spots were storage proteins, such as gliadin and low-molecular mass glutenin subunit. Five protein spots were identified as dehydroascorbate reductase (Triticum aestivum), triticin precursor (T. aestivum), alpha-amylase inhibitor (Oryza sativa), DNA-binding with one finger (Dof) zinc family protein (O. sativa), and nonphototropic hypocotyl 1 (NPH1) protein (Avena sativa). The other protein spots appeared to be hypothetical proteins (O. sativa or Arabidopsis thaliana) or functional unknown proteins. These specific proteins can be used as markers to identify wheat cultivars in blended flour composed of two or three flours.

Zilić S, Barać M, Pešić M, Dodig D, Ignjatović-Micić D. Characterization of proteins from grain of different bread and durum wheat genotypes. Int J Mol Sci. 2011;12(9):5878-94. doi: 10.3390/ijms12095878. 

Abstract. The classical Osborne wheat protein fractions (albumins, globulins, gliadins, and glutenins), as well as several proteins from each of the four subunits of gliadin using SDS-PAGE analyses, were determined in the grain of five bread (T. aestivum L.) and five durum wheat (T. durum Desf.) genotypes. In addition, content of tryptophan and wet gluten were analyzed. Gliadins and glutenins comprise from 58.17% to 65.27% and 56.25% to 64.48% of total proteins and as such account for both quantity and quality of the bread and durum wheat grain proteins, respectively. The ratio of gliadin/total glutenin varied from 0.49 to 1.01 and 0.57 to 1.06 among the bread and durum genotypes, respectively. According to SDS-PAGE analysis, bread wheat genotypes had a higher concentration of α + β + γ-subunits of gliadin (on average 61.54% of extractable proteins) than durum wheat (on average 55.32% of extractable proteins). However, low concentration of ω-subunit was found in both bread (0.50% to 2.53% of extractable proteins) and durum (3.65% to 6.99% of extractable proteins) wheat genotypes. On average, durum wheat contained significantly higher amounts of tryptophan and wet gluten (0.163% dry weight (d.w.) and 26.96% d.w., respectively) than bread wheat (0.147% d.w. and 24.18% d.w., respectively).

Day L, Bhandari DG, Greenwell P, Leonard SA, Schofield JD. Characterization of wheat puroindoline proteins. FEBS J. 2006 Dec;273(23):5358-73. doi: 10.1111/j.1742-4658.2006.05528.x. 

Abstract. Puroindoline proteins were purified from selected UK-grown hexaploid wheats. Their identities were confirmed on the basis of capillary electrophoresis mobilities, relative molecular mass and N-terminal amino acid sequencing. Only one form of puroindoline-a protein was found in those varieties, regardless of endosperm texture. Three allelic forms of puroindoline-b protein were identified. Nucleotide sequencing of cDNA produced by RT-PCR of isolated mRNA indicated that these were the 'wild-type', found in soft wheats, puroindoline-b containing a Gly-->Ser amino acid substitution (position 46) and puroindoline-b containing a Trp-->Arg substitution (position 44). The latter two were found in hard wheats. Microheterogeneity, due to short extensions and/or truncations at the N-terminus and C-terminus, was detected for both puroindoline-a and puroindoline-b. The type of microheterogeneity observed was more consistent for puroindoline-a than for puroindoline-b, and may arise through slightly different post-translational processing pathways. A puroindoline-b allele corresponding to a Leu-->Pro substitution (position 60) was identified from the cDNA sequence of the hard variety Chablis, but no mature puroindoline-b protein was found in this or two other European varieties known to possess this puroindoline-b allele. Wheats possessing the puroindoline-b proteins with point mutations appeared to contain lower amounts of puroindoline protein. Such wheats have a hard endosperm texture, as do wheats from which puroindoline-a or puroindoline-b are absent. Our results suggest that point mutations in puroindoline-b genes may confer hard endosperm texture through accumulation of allelic forms of puroindoline-b proteins with altered functional properties and/or through lower amounts of puroindoline proteins.

Bancel E, Bonnot T, Davanture M, Branlard G, Zivy M, Martre P. Proteomic Approach to Identify Nuclear Proteins in Wheat Grain. J Proteome Res. 2015 Oct 2;14(10):4432-9. doi: 10.1021/acs.jproteome.5b00446.

Abstract. The nuclear proteome of the grain of the two cultivated wheat species Triticum aestivum (hexaploid wheat; genomes A, B, and D) and T. monococcum (diploid wheat; genome A) was analyzed in two early stages of development using shotgun-based proteomics. A procedure was optimized to purify nuclei, and an improved protein sample preparation was developed to efficiently remove nonprotein substances (starch and nucleic acids). A total of 797 proteins corresponding to 528 unique proteins were identified, 36% of which were classified in functional groups related to DNA and RNA metabolism. A large number (107 proteins) of unknown functions and hypothetical proteins were also found. Some identified proteins may be multifunctional and may present multiple localizations. On the basis of the MS/MS analysis, 368 proteins were present in the two species, and in two stages of development, some qualitative differences between species and stages of development were also found. All of these data illustrate the dynamic function of the grain nucleus in the early stages of development.