Phytochemical investigation and antioxidant properties of unripe tomato cultivars (Solanum lycopersicum L.)

Unripe tomatoes are among the main waste produced during tomato cultivation and processing. In this study, unripe tomatoes from seven different Italian cultivars have been investigated to evaluate their nutraceutical potential. Phytochemical investigation allowed shedding light on the identification of seventy-five bioactive compounds. The highest amount of polyphenolic and glycoalkaloids along with the high level of antioxidant activities was found in the Datterini tomatoes variety. The peculiarity of this variety is the high chlorogenic acid content, being ten times higher compared to the other cultivars examined. Moreover, the total α-tomatine amount has been found substantially higher (34.699 ± 1.101 mg/g dry weight) with respect to the other tomato varieties analyzed. Furthermore, the cultivars metabolomic profiles were investigated with the PCA approach. Based on Datterini cultivar's metabolomic profile, its waste-recovery could represent a good option for further added value products in pharmaceutical and nutraceutical areas with a high α-tomatine content.

Effect of the nixtamalization process on the protein bioaccessibility of white and red sorghum flours during in vitro gastrointestinal digestion

Protein bioaccessibility is a major concern in sorghum (Sorghum bicolor L. Moench) due to potential interactions with tannins affecting its nutritional value. Technological treatments such as boiling or alkaline cooking have been proposed to address this problem by reducing tannin-protein interactions. This research aimed to evaluate the impact of nixtamalization in the protein bioaccessibility from two sorghum varieties (red and white sorghum) during in vitro gastrointestinal digestion. Nixtamalization increased protein bioaccessibility in the non-digestible fraction (NDF) (5.26 and 26.31% for red and white sorghum, respectively). However, cooking showed a higher permeation speed of protein from red sorghum flours at the end of the intestinal incubation (9.42%). The SDS-PAGE profile of the digested fraction (DF) at 90 min of intestinal incubation indicated that, for red sorghum, cooking allows the formation of α and γ-kafirins while nixtamalization increase α-kafirin release. Principal Components Analysis (PCA) showed the association between nixtamalization and dissociation of δα kafirin complexes and increased protein content in the digestible fraction. In silico interactions indicated the highest biding energies for (+)-catechin and kafirin fractions (β-kafirin: -7.0 kcal/mol; γ-kafirin: -5.8 kcal/mol, and δ-kafirin: -6.8 kcal/mol), suggesting a minor influence of depolymerized proanthocyanidin fractions with sorghum proteins as a result of the nixtamalization process. In conclusion, nixtamalization increased the bioaccessibility of sorghum proteins, depolymerizing condensed tannins, and breaking protein-tannin complexes. Such technological process improves the nutrimental value of sorghum, supporting its inclusion in the human diet.

Comparative analysis of pigments in red and yellow banana fruit

Color is an important characteristic determining the fruit value. Although ripe bananas usually have yellow peels, several banana cultivars have red peels. As details of the pigments in banana fruits are unknown, we investigated these pigments contents and compositions in the peel and pulp of red cultivar 'Hongjiaowang' and yellow cultivar 'Baxijiao' by UPLC-PDA-QTOF-MS and HPLC-PDA techniques. The 'Hongjiaowang' peel color was mainly determined by the presence of anthocyanin-containing epidermal cells. Rutinoside derivatives of cyanidin, peonidin, petunidin, and malvidin were unique to the red peel, and possibly responsible for the red color. 'Hongjiaowang' contained higher total content of carotenoids than 'Baxijiao' in both pulp and peel. Lutein, α-carotene, and β-carotene were main carotenoids, which might play a more important role than flavonoids in producing the yellow banana color owing to the properties and distribution in the fruit. The information will help us understand a complete profile of pigments in banana.

Formation of polymeric pigments in red wines through sequential fermentation of flavanol-enriched musts with non-Saccharomyces yeasts

Non-Saccharomyces yeasts may contribute to enrich wine aroma while promoting the formation of stable pigments. Yeast metabolites such as acetaldehyde and pyruvate participate in the formation of stable pigments during fermentation and wine aging. This work evaluated the formation of polymeric pigments in red musts added with (+)-Catechin, ProcyanidinB2 and ProcyanidinC1. The non-Saccharomyces yeasts used were Lachancea thermotolerans, Metschnikowia pulcherrima and Torulaspora delbrueckii in sequential fermentation with Saccharomyces cerevisiae and Schizosaccharomyces pombe. Use of Lachancea thermotolerans led to larger amounts of polymeric pigments in sequential fermentation. (+)-Catechin is the flavanol prone to forming such pigments. The species Metschnikowia pulcherrima produced higher concentration of esters and total volatile compounds. The sensory analysis pointed out differences in fruitiness and aroma quality. The results obtained strengthen the fact that metabolites from non-Saccharomyces yeasts may contribute to form stable polymeric pigments while also influencing wine complexity.