Sugar, Nonvolatile Acid, 13C/12C Ratio, and Mineral Analysis for Determination of the Authenticity and Quality of Red Raspberry Juice Composition

Abstract

Abstract Analyses of sugars, nonvolatile acids, 13C/12C ratios, and minerals were conducted on 46 samples of red raspberry (Rubus idaeus) to develop a compositional database for evaluating authenticity and quality. Sample differences included cultivar (n = 10) and factors such as maturity, geographic origin, mold contamination, and harvesting procedures. A pilot-plant process typical of conventional commercial processing operations was used to process juices, along with newer technologies such as enzymatic liquefaction, diffusion extraction, and direct osmotic concentration. °Brix ranged from 7.0 to 15.0 with a mean of 9.95. All data have been normalized to 9.2 °Brix. Sorbitol expressed as percentage of total sugars ranged from 0 to 0.5% with a mean of 0.15%. Sucrose levels (range, 0–24.1%; mean, 1.4%) were highly variable. The glucoserfructose ratio ranged from 0.76 to 1.03 with a mean of 0.93. Citric acid is the major acid, ranging from 89.8 to 98.9% of total acids (mean, 95.6%; 1.70 g/100 mL). Malic acid ranged from 0.3 to 9.6% of total acids with a mean of 3.3% (66.1 mg/100 mL). Isocitric acid ranged from 0.2 to 2.6% (5.7–44.0 mg/100 mL) with mean of 1.1% (17.0 mg/100 mL). Potassium ranged from 108 to 400 mg/100 mL with a mean of 227.8 mg/100 mL. Sodium ranged from 0.2 to 4.0 mg/100 mL with a mean of 2.1 mg/100 mL. Magnesium ranged from 11.3 to 29.4 mg/100 mL with a mean of 18.6 mg/100 mL. Calcium ranged from 8.0 to 16.3 mg/100 mL with a mean of 12.5 mg/100 mL. 13C/12C ratios ranged from –26.0 to –21.9‰ PDB (PeeDee Belemnite) with a mean of –24.2‰.