Use of Chemometrics for Correlating Carobs Nutritional Compositional Values with Geographic Origin

Abstract

Carobs unique compositional and biological synthesis enables their characterization as functional foods. In the present study, 76 samples derived from fruit and seeds of carobs, with origin from the countries of the Mediterranean region (Cyprus, Greece, Italy, Spain, Turkey, Jordan and Palestine) were analyzed for their nutritional composition, in order to identify potential markers for their provenance and address the carobs' authenticity issue. Moisture, ash, fat, proteins, sugars (fructose, glucose, sucrose), dietary fibers and minerals (Ca, K, Mg, Na, P, Cu, Fe, Mn, Zn) were estimated following official methods. Due to the large number of data (76 samples × 17 parameters × 7 countries), chemometric techniques were employed to process them and extract conclusions. The samples of different geographical origin were discriminated with 79% success in total. The carobs from Cyprus, Italy and Spain were correctly classified without error. The main discriminators were found to be the dietary fibers, the carbohydrates and Cu, Zn and Mn, which emphasize their specific nutritional added value to the product and the country of origin impact. The results suggest that the proposed analytical approach is a powerful tool that enables the discrimination of carobs based on their country of origin. This research contributes to authenticity of carobs, adding value to local products.Metabolites 2020, 10, 62 2 of 11 demands. Carob flesh is rich in minerals, dietary fibers, sugars, polyphenols, D-pinitol and with low fat content, whereas the seed is abundant with locust bean gum (E 410), a natural hydrocolloid widely used in the food industry [3][4][5][6][7]. The chemical composition of carob flesh is presented in Table 1; however, these values are affected by various practices and factors (e.g., farming, genotyping, climate, soil, etc.). Environmentally speaking, the wide presence of carobs in the Mediterranean region can be attributed to combat the negative effects of climate change. The biological importance of carob leaves as a potential antifeedant was recently revealed [8]. The complexity of carob metabolome in combination with origin, ripening and roasting was studied using hyphenated state-of-the-art liquid and gas mass spectrometric systems [9]. The positive biological effects of carobs in the gastrointestinal tract, consumed either as water diluted food [10] or as an alcoholic drink [11], is still triggering the interest of researchers. Last but not least, is the carob's unique sensorial characteristics, as both the fruit and the carob-products, are associated with a strong and persisting unique aroma [12].

Mapping the Primary and Secondary Metabolomes of Carob (Ceratonia siliqua L.) Fruit and Its Postharvest Antioxidant Potential at Critical Stages of Ripening

“…The strong genotype effect on K concentration is reflected in the slightly lower concentrations reported by Kokkinofta et al (2020) for carob genotypes sourced from Cyprus and Italy (9.03 and 10.33 mg g −1 dw) and the two-fold higher content (24.7 mg g −1 dw) found by Musa Özcan et al (2007) in Turkish carobs. Similarly, the genotype effect on Mg concentrations is evident not only among the genotypes currently reported, which are comparable to those found in Jordanian carobs (0.82 mg g −1 dw [ 34 ]) but, also, in comparison to Turkish genotypes that present significantly higher Mg content [ 33 ]. Calcium was the second-most abundant macro-mineral found in carob pulp in concentrations 2.21 ± 0.21 mg g −1 dw, similar to those (2.38 mg g −1 dw) reported by Kokkinofta et al (2020) but half of those reported for Turkish carobs (4.21 mg g −1 dw [ 33 ]).…”

“…The fruit moisture content stabilized at a low of 8.78–9.75% at commercial maturity (RS5 and RS6), which is similar to the levels reported by Vekiari et al (9.01% ± 0.99%; 2012) [ 17 ] and Othmen et al (9.03% ± 11.30%; 2019) [ 18 ] but higher than those of Musa Özcan et al (6.01% ± 0.11%; 2007) [ 33 ]. Moisture contents in carob pulp as high as 19.18% have been reported [ 34 ], which are likely due to premature harvest. At RS5 and RS6, the respiration rate dropped below 5 mL CO 2 kg −1 h −1 , which ranks ripe carob fruit as a very low respiring horticultural commodity, along with dates, nuts and dehydrated fruits and vegetables, predisposed for long-term storage, with a low production of vital heat [ 35 , 36 ].…”

Pod Morphology, Primary and Secondary Metabolite Profiles in Non-grafted and Grafted Carob Germplasm Are Configured by Agro-Environmental Zone, Genotype, and Growing Season

“…The present study also emphasizes that seasonal effect on compositional traits should also be considered. Despite previous efforts to categorize carobs according to their geographical origin ( Farag et al, 2019 ; Kokkinofta et al, 2020 ), these works suffer from the limited description either of the genetic profile or the environmental conditions where trees were grown, moreover they lack replication in time. These limitations that are not easily manageable for an underutilized tree crop like carob, warrant international cooperation for the establishment of ex situ collections of the same divergent genetic material in different agro-environmental zones to allow accurate assessment of the genotypic, agro-environmental and seasonal effects on carob compositional traits and to facilitate association mapping studies.…”

Anti-Cancer Activity and Phenolic Content of Extracts Derived from Cypriot Carob (Ceratonia siliqua L.) Pods Using Different Solvents

“…Kibble size was found to be an important parameter in determining the chemical characteristics of the resulting carob juice produced by different extraction methods [ 24 ]. The geographical origin, type and nutritional composition of carobs from Cyprus and other countries, were differentiated based on Fourier transform infrared (FTIR) spectroscopy and chemometrics [ 25 , 26 ]. In addition, the profile of biogenic volatile organic compounds (VOCs) emitted from carob fruit that contribute to its unique aroma, has been recently described [ 27 ].…”