Optimization of Gluten-Free Bread Formulation with Quercus pubescens Acorn Flour, Whey Proteins and Xanthan Gum Using Response Surface Methodology and Computer Vision Analysis

Abstract

U ovom radu istražen je utjecaj dodatka koncentrata proteina sirutke i ksantan gume na fizikalna, strukturna, teksturalna i senzorska svojstva kruha bez glutena pripremljenog na osnovi mješavine rižinog brašna i brašna žira hrasta medunca (Quercus pubescens). Primjenom metode odzivnih površina (RSM) ispitani su odgovori: svjetlina i kromatske komponente boje (L*, a*, b*), teksturalni parametri (otpornost na žvakanje, elastičnost, kohezivnost), broj i veličina šupljina, ukupna poroznost, specifični volumen i senzorska prihvatljivost. Rezultati su pokazali da oba dodatka imaju značajan, često nelinearan i međusobno ovisan utjecaj na navedena svojstva. Proteini sirutke povećali su svjetlinu (L*), veličinu šupljina i ukupnu poroznost, ali smanjili broj šupljina, kohezivnost i elastičnost. Ksantan guma je povećala broj šupljina, otpornost na žvakanje, elastičnost, kohezivnost i senzorsku prihvatljivost, no u višim koncentracijama djelovala je negativno na teksturalna svojstva. Kvadratni i linearni modeli imali su visoke vrijednosti koeficijenata determinacije (R² > 0,9), a računalna analiza slike omogućila je objektivnu kvantifikaciju strukturnih promjena. Optimalna formulacija (15 % proteina sirutke, 1,47 % ksantan gume) rezultirala je najvišom senzorskom ocjenom (7,83/9), dobrom poroznošću (33,12 %) i minimalnim otporom žvakanju. Statistički modeli i provedena optimizacija pokazali su visoku pouzdanost i primjenjivost u razvoju i industrijskoj validaciji bezglutenskih formulacija.This study investigated the effects of whey protein concentrate and xanthan gum on the physical, structural, textural, and sensory properties of gluten-free bread formulated from a mixture of rice flour and downy oak (Quercus pubescens) acorn flour. Using response surface methodology (RSM), key quality parameters were evaluated, including crumb color (L*, a*, b*), textural attributes (chewiness, elasticity, cohesiveness), pore number and size, total porosity, specific volume, and sensory acceptability. The results showed that both additives exerted significant, often nonlinear and interactive effects on the measured responses. Whey protein increased crumb brightness (L*), pore size, and porosity, but decreased the number of pores, elasticity, and cohesiveness. Xanthan gum enhanced pore number, chewiness, elasticity, cohesiveness, and sensory quality, but at higher concentrations, it negatively affected texture. The statistical models showed high predictive reliability (R² > 0.9), and image analysis was successfully used to objectively quantify crumb structure. The optimal formulation (15% whey protein, 1.47% xanthan gum) achieved the highest sensory score (7.83/9), favorable porosity (33.12%), and minimal chewiness. The RSM models and optimization confirmed the potential for application in the development and industrial validation of gluten-free formulations