Varietal Comparison of The Chemical, Physical, and Mechanical Properties of Five Colored Table Grapes

Abstract

The visual attributes of table grapes, their chemical constituents and mechanical properties are involved in consumer acceptability because they are correlated to sensory perception. Usually, instrumental measurements are preferred to the sensory evaluations because they reduce variations in subjective judgments and can be carried out more easily. In this work chemical-physical attributes and texture properties of five black table grapes (Alphonse Lavallée, Black magic, Cardinal, Perlon, Regina nera) were studied in order to identify significant varietal differences.Spectrophotometric and HPLC methods and Texture Analysis test were used to evaluate color index, sugars and acid composition, phenolic characteristics and mechanical properties of the skin and the pulp of berries. Many differences were found among varieties in technological maturity indexes, hydroxycinnamic acid, anthocyanin content and profile and relative CIE L*, a*, b* parameters, but the more relevant differences were found in mechanical properties. Principal Component Analysis showed that the TPA parameters (hardness, cohesiveness, gumminess, resilience) and berry skin characteristics (break skin energy, skin modulus of elasticy) were the best indices able to fulfill the aim of this work. Almost all the parameters showed differences among cultivars, confirming their importance in the characterization of the variety as well as in the assessment of potential consumer acceptability. In particular, the cultivars demonstrated different reactions to the compression test; thus, the texture analysis parameters can be appropriate to explain varietal differences and to allow their differentiation.

Berry density and size as factors related to the physicochemical characteristics of Muscat Hamburg table grapes (Vitis vinifera L.)

“…A UV-1800 spectrophotometer (Shimazdu Corporation, Kyoto, Japan) was used. The relative standard deviation (RSD) based on repeated analysis (n = 12) of the same sample was 1.58%, 1.82%, 1.14%, 2.80%, 0.93% and 1.74% for TP, HCA, TA, FRV, TF and PRO, respectively (Río Segade, Giacosa, de Palma et al, 2013;Rolle et al, 2013).…”

“…The pulp was introduced into a tube containing 100 mg sodium metabisulphite, weighed and subsequently diluted (9:1, m/m) with 5 mol/L sulphuric acid (Rolle, Giacosa, Gerbi, Bertolino, & Novello, 2013;Rolle, Giacosa, Gerbi, & Novello, 2011;Río Segade, Giacosa, de Palma et al, 2013). Afterwards, the pulp was homogenised at 9500 rpm for 30 s with an Ultraturrax T10 high-speed homogenizer (IKA Labortechnik, Staufen, Germany) and centrifuged in a PK 131 centrifuge (ALC International, MI, Italy) for 15 min at 3000Âg at 20°C.…”

“…The resulting solution was then used for pulp analysis. The skins were weighed and quickly immersed into 25 mL of a hydroalcoholic buffer (pH 3.2) containing 5 g/L tartaric acid, 2 g/L sodium metabisulphite and 12% v/v ethanol (Río Segade, Giacosa, de Palma et al, 2013;Rolle et al, 2013). Afterwards, the skins were homogenised at 8000 rpm for 1 min with an Ultraturrax T25 high-speed homogenizer (IKA Labortechnik) and centrifuged for 15 min at 3000Âg at 20°C.…”

Investigation on Phenolic and Aroma Compounds of Table Grapes from Romania

“…(Crupi et al, 2012;Dami et al, 2006;Kamiloglu, 2011;Liang et al, 2011;Orak, 2006). The 'Napoca' variety had the highest amount of anthocyanins, with a prevalence of malvidin derivatives and high percentages of acylated anthocyanin forms, similar to the 'Regina nera' table grape cultivar (Rolle et al, 2013a). In the grape juice production, the phenolic content and the juice color are important factors, the latter also for the direct consumer perception (Kliewer, 1970).…”

“…Anthocyanin profile. The determination of individual anthocyanins in the skin extracts was performed after reversephase solid-phase extraction using a 1-g Sep-Pak C18 cartridge (Waters Corporation, Milford, MA) and elution with methanol (Rolle et al, 2013a). The HPLC -Diode Array Detector (DAD) system and chromatographic conditions have been previously described (Rolle et al, 2013a).…”