International Multidimensional Authenticity Specification (IMAS) Algorithm for Detection of Commercial Pomegranate Juice Adulteration

Abstract

The pomegranate fruit ( Punica granatum ) has become an international high-value crop for the production of commercial pomegranate juice (PJ). The perceived consumer value of PJ is due in large part to its potential health benefits based on a significant body of medical research conducted with authentic PJ. To establish criteria for authenticating PJ, a new International Multidimensional Authenticity Specifications (IMAS) algorithm was developed through consideration of existing databases and comprehensive chemical characterization of 45 commercial juice samples from 23 different manufacturers in the United States. In addition to analysis of commercial juice samples obtained in the United States, data from other analyses of pomegranate juice and fruits including samples from Iran, Turkey, Azerbaijan, Syria, India, and China were considered in developing this protocol. There is universal agreement that the presence of a highly constant group of six anthocyanins together with punicalagins characterizes polyphenols in PJ. At a total sugar concentration of 16 degrees Brix, PJ contains characteristic sugars including mannitol at >0.3 g/100 mL. Ratios of glucose to mannitol of 4-15 and of glucose to fructose of 0.8-1.0 are also characteristic of PJ. In addition, no sucrose should be present because of isomerase activity during commercial processing. Stable isotope ratio mass spectrometry as > -25 per thousand assures that there is no added corn or cane sugar added to PJ. Sorbitol was present at <0.025 g/100 mL; maltose and tartaric acid were not detected. The presence of the amino acid proline at >25 mg/L is indicative of added grape products. Malic acid at >0.1 g/100 mL indicates adulteration with apple, pear, grape, cherry, plum, or aronia juice. Other adulteration methods include the addition of highly concentrated aronia, blueberry, or blackberry juices or natural grape pigments to poor-quality juices to imitate the color of pomegranate juice, which results in abnormal anthocyanin profiles. To adjust the astringent taste of poor-quality juice or peel extract, addition of nonpomegranate sugars is a commonly detected adulteration method. The profile generated from these analyses combined with information from existing databases and published literature has been integrated into a validated IMAS for PJ, which can be utilized to detect PJ adulteration. In this survey of commercial pomegranate juices, only 6 of 23 strictly met all of the IMAS criteria.

HS-GC–MS volatile compounds recovered in freshly pressed ‘Wonderful’ cultivar and commercial pomegranate juices

“…Analogous to satsuma work recently reported (Beaulieu et al, 2014), the essence data indicate that many volatiles are lost and that even a mildly oxidative process to produce a concentrate for reconstituted juices resulted in probable flavor/aroma loss. Therefore, commercially adding back essence, flavor packs or as some authors suggest, adulterants (Nuncio-Jauregui et al, 2014;Vazquez-Araujo et al, 2011b;Zhang et al, 2009), might be preferred commercially to achieve consistent consumer satisfaction.…”

HPLC–PDA–MS fingerprinting to assess the authenticity of pomegranate beverages

“…The antioxidant capacity of commercial pomegranate juices, some of which are higher than that of several other (poly)phenolic-rich beverages, such as tea and red wines, has been attributed to the presence of hydrolysable tannins including gallotannins, and the ellagitannins, punicalagin and punicalin (Seeram et al, 2008;Martin, Krueger, Rodriquez, Dreher & Reed, 2008;Borges, Mullen & Crozier, 2010;Viuda-Martos & Fernández-López, 2010;Faria, 2011). Pomegranates also contain anthocyanins with the principal components being 3-O-glucosides and 3,5-O-diglucosides of cyanidin and delphinidin (Gil, Tomás-Barberán, Hess-Pierce, Holcroft, & Kader, 2000;Zhang et al, 2009). The polyphenol composition of pomegranate is both complex and unique and as such can be used as a fingerprint by the food industry for quality control purposes.…”

Modern analytical methods for the detection of food fraud and adulteration by food category

“…Other highly concentrated juices (aronia, blueberry or blackberry) or natural grape pigments are added to imitate the color of pomegranate juice and poor quality juice or peel extract with non‐pomegranate sugars is added for a stringent taste. Authentic commercial pomegranate juice is characterized by a consistent composition of components such as pomegranate polyphenols, sugar profiles, organic acids, amino acids and potassium using HPLC and flame photometry . FTIR is an especially good method for providing a rapid classification of pomegranate juice concentrate and grape juice concentrate …”