Comparative elucidation of garlic peeling methods and positioning of quality characteristics using principal component analysis

Abstract

Background. Garlic ( Allium sativum ) peeling is one of the crucial steps in its use and is a significant chal - lenge for maintaining the peeled garlic’s quality. The peeling of garlic on a mass scale is required to produce dehydrated garlic flakes, powder, grits, paste, garlic pickle, and for use as a critical wet spice in various processed products. Materials and methods. Manual peeling (MP), normal water peeling (NWP), hot water peeling (HWP), flame peeling (FP), and lye peeling (LP) methods were assessed for the quality characteristics of peeled garlic cloves based on antioxidant activities (AOA), total phenolic content (TPC), total flavonoid content (TFC), anti-nutritional properties, ascorbic acid (AA), reducing sugar, allicin, and pyruvic acid content. Principal component analysis (PCA) was used to develop the correlations between the garlic peeling methods and the measured parameters. Morphological and Energy Dispersive X-Ray (EDX) analyses were used to verify the difference between the optimized method of peeled garlic over the manually peeled garlic. Results. All peeling methods of garlic resulted in the respective peeled garlic having a pH in the acidic range (6.08–6.14). Reducing sugar is an important component affecting the color of the dehydrated garlic, which was found to be minimal in NWP (275.64 mg/g, fresh weight) and LP (335.26 mg/g, fresh weight). Allicin content, pyruvic acid, TPC, TFC, and AOA were similar for manually and lye-peeled garlic. MP garlic had the highest levels of anti-nutritional factors, such as saponin, phytic acid, and tannin. Whereas, the minimum level of saponin was found in HWP garlic. Phytic acid and tannin content were found to be minimum in LP and FP garlic. Multivariate analysis showed that the estimated chemical attributes were found to have the maximum number of positive correlations with the LP methods of garlic. At the same time, it also showed less correlation with anti-nutritional properties and a negative correlation with reducing sugar. Thus, the lye peeling (LP) method may be applied commercially for garlic peeling on a commercial scale due to it main - taining the quality characteristics; the morphological and EDX analyses also support this finding. Conclusions. LP method was found to be the best method of peeling since it maintained the allicin content, antioxidant properties, and reduced anti-nutritional properties and doesn’t reduce sugar.