Chemical and Sensory Characterisation of Two Rubus rosifolius (Red Raspberry) Varieties

Raspberries are economically important fruits, being highly valued for their taste and medicinal properties. Prior to our recent finding, the occurrence of different varieties of Rubus rosifolius growing in Jamaica had not been previously reported. Upon close observation of the plants, differences in various physical features pointed to the existence of two distinct plant morphotypes, which were described as Red “R” and Wine Red “WR.” With an aim to determine which variety may be more favourable for value-added food production, we undertook their physicochemical and sensory analysis. This characterisation led to the rationalisation of the differences in the perceived sensory properties of these biologically active fruits. Total phenolic content was determined using the Folin-Ciocalteu reagent assay, and the identification and quantification of anthocyanins were done via HPLC-MS and HPLC-UV, respectively. Proximate and physicochemical analyses were also carried out. The findings of the analyses were associated with those of a consumer sensory analysis. The WR fruits had a greater quantity of the deep red anthocyanin, cyanidin-3-glucoside (66.2 mg/100 g FW), and a significantly lower lightness value. They also received a significantly higher sweetness score, which is associated with their higher total sugar content (4.8 g/100 g) and maturity index (6.7). The R fruits had a higher quantity of the orange-coloured pelargonidin-3-rutinoside (17.2 mg/100 g FW) and significantly higher titratable acidity (1.3 g citric acid/100 mL), the latter being associated with its significantly more sour taste. The high total phenolic contents suggest a health-functional value of these R. rosifolius berry fruits. Our findings, which revealed that the WR variety was the preferred choice among consumers, may be used to guide future product-development endeavours of these commercially valuable fruits

Hypoglycemic effect of the fruit extracts of two varieties of Rubus rosifolius

Oral glucose tolerance test on male Sprague–Dawley rats was done to determine the hypoglycemic effect of the n-hexane, ethyl acetate and methanol fruit extracts (50 mg/kg BW; oral administration) of two varieties of Rubus rosifolius. Metformin was used as a positive control (15 mg/kg BW; intravenous administration). The n-hexane extract was most potent and was investigated phytochemically to yield compound 1, a mixture of triacylglycerols. In its oxidized state compound 1 produced a significant hypoglycemic effect which was more effective than metformin for the first 30 min of the assay (p = .03) and not significantly different for up to 120 min. Mechanisms through which the oxidized triacylglycerol species could form were explored and presented. This is the first account of the hypoglycemic activity of R. rosifolius and it is also the first account of this activity being credited to compounds other than polyphenols and terpenes in Rubus plants

Morphological Characterisation of Wild Rubus rosifolius (Rosaceae) Plants Growing in Jamaica Prior to Agricultural Pursuits

Precise identification of plants is critical for informed agriculture where nutraceutical properties and productivity are simultaneously important. The Jamaican-grown West Indian raspberry (Rubus rosifolius) falls into this category. The first step to taking this wild-growing plant into agricultural production is morphological identification. Although there are no botanical reports of multiple varieties of this species in Jamaica, two morphotypes were found, which were named ‘Red' and ‘Wine Red’ based on fruit colour. Morphological methods were used to characterise these plants growing at Holywell (located over 900 m above sea level), in the Blue Mountain region of Jamaica. Morphological analyses revealed that growth form, leaf, flower, and fruit characteristics of the morphotypes were statistically distinctive between the two morphotypes for 48 of the 59 measured parameters. Several descriptors allowed the morphotypes to be distinguished before their fruits became visible. These findings support the hypothesis that there is a standard morphotype having a scrambling morphology, smaller leaves, and darker red, oblong, solitary fruits (Wine Red, WR), and a distinct morphotype with more upright stems, larger leaves, and lighter red, spherical, bunched fruits (Red, R). This information can now be used to facilitate molecular analyses and ramp-up clonal production of these morphotypes to determine the agricultural factors that are linked to yield and nutritionally relevant traits