Classification of commercial Omani Halwa by physico-chemical properties and instrumental texture profile analysis (TPA)

Commercially available Omani halwa from the local market was classified based on its composition and instrumental texture profile. The products were grouped into four classes based on cluster analysis. None of the attributes of the instrumental Texture Profile Analysis (TPA) were correlated significantly with the ash, colour and pH values (p<0.05), while specific attributes did correlate with specific aspects of the chemical composition. All TPA attributes were significantly correlated with specific types of fatty acid. Hardness was correlated significantly with the moisture and sugar contents, while adhesiveness was correlated significantly with the moisture, sugar and non-sugar carbohydrate contents (p<0.05). Springiness was correlated with sugar and non-sugar carbohydrate. The firmness and chewiness were correlated with moisture and the total fat, saturated and unsaturated fat contents (p<0.05). Cohesiveness-1 was correlated only with the protein, total fat, saturated and un-saturated fat contents, while cohesiveness-2 was correlated with sugar, total fat, saturated and unsaturated fat (p<0.05). The resilience was correlated with the total fat, saturated and unsaturated fatty acids, while gumminess was only correlated with the moisture content. The link between TPA and physico-chemical characteristics was established using multivariate matrix correlations and revealed that the pattern of texture attributes was mostly linked to the moisture and fat contents. Principal component analysis was carried out to identify the main physico-chemical properties and TPA attributes of the four classes of halwa as determined by cluster analysis. The four classes of halwa could be characterised as soft-resilient, soft-springy-cohesive, soft-springy and hard-chewy.