Nutritional ingredient by-product of the pistachio oil industry: physicochemical characterization.

Pistachio flour obtained from oil industry was nutritionally characterized for use as food ingredient in functional foods. Proximal composition, jointly with mineral content, amino acids and fatty acid profile were studied. In addition, different components present in this food ingredient have been analyzed by attenuated total reflectance Fourier transform infrared spectroscopy and thermal properties of proteins were evaluated by differential scanning calorimetry. This flour presented high mineral content such as potassium, phosphorus, magnesium and calcium. Moreover, high amount of unsaturated fatty acids, mainly oleic and linoleic were found. Secondary structure of proteins mainly was formed by parallel ß-sheet and α-helix. In the by-product, pistachio protein is in a native state and is able to be denatured at temperatures higher than 100 °C. Therefore, food processing of this ingredient can affect the structure of components.

Flour from mature Prosopis nigra pods as suitable substrate for the synthesis of prebiotic fructo-oligosaccharides and stabilization of dehydrated Lactobacillus delbrueckii subsp. bulgaricus.

Prosopis nigra, a sucrose-rich crop, was used to enzymatically synthesize fructo-oligosaccharides (FOS). The obtained products were used as stabilizing matrices during freeze-drying and storage of Lactobacillus delbrueckii subsp. bulgaricus CIDCA 333. The centesimal composition of P. nigra flour was firstly determined. FOS were synthesized using Viscozyme L as biocatalyst. The progress of the enzymatic reaction was monitored by HPLC and compared with a reaction carried out using equivalent concentrations of pure sucrose as substrate (control). Then, P. nigra containing or not the obtained FOS (P. nigra + FOS or P. nigra) were used as matrices for freeze-drying and storage of L. delbrueckii subsp. bulgaricus CIDCA 333. P. nigra flour was rich in simple sugars (sucrose and fructose), total dietary fiber, and polyphenols. The main products of synthesis were FOS with degrees of polymerization (DP) within 3 and 5, and these results were comparable with those of the controls. DP3 was the first product obtained, attaining the maximal production after 1.29 hours of synthesis. The maximal production of total FOS (DP3 + DP4 + DP5) was achieved after 2.57 hours, indicating that larger FOS (DP4, DP5) were produced from DP3. Glucose was obtained as secondary product, but with significantly lower Vmax and Kf (maximal velocity for the production and constant for the formation) than DP3. Both P. nigra + FOS or P. nigra matrices stabilized the highly sensitive L. delbrueckii subsp. bulgaricus CIDCA 333 strain during freeze-drying and storage for up to 140 days at 4 °C, and were significantly better protectants than the controls of sucrose (p <0.05). The concomitant presence of prebiotics (FOS), antioxidants (polypyhenols) and lactic acid bacteria in the matrices provides a smart strategy to increase the value of this underutilized regional crop, turning it in an interesting ingredient potentially useful in the food industry.

Comparative analysis of protein composition and digestibility of Ceratonia siliqua L. and Prosopis spp. seed germ flour.

By virtue of exclusive nutrient composition and nutritional properties, seed germ flours from both European carob (Ceratonia siliqua L.) and South American algarrobo (Prosopis alba and Prosopis nigra) or vinal (Prosopis ruscifolia) have potential as a high nutritional value and health-promoting ingredient for food formulations. In order to define their compositional and functional properties, we investigated the germ protein content of carob compared to the P. alba, P. nigra and P. ruscifolia counterparts, applying proteomics and complementary methods. The mono- and two-dimensional electrophoretic profiles of Prosopis spp. were very similar among one another, while C. siliqua exhibited significant differences. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy highlighted a dominant ß-sheet structural conformation for C. siliqua, suggesting that carob germ flour might more suited than Prosopis germ flour for baking and food technological applications. In contrast, Prosopis spp. contained a more adequate nutritional value than C. siliqua, in terms of essential amino acid complement. Both carob and algarrobo germ flour samples were highly digestible, as demonstrated by in vitro simulated gastrointestinal digestion, releasing high amounts of free amino acids and only minor proportions of low molecular weight peptides.

Comparative analysis of C-glycosidic flavonoids from Prosopis spp. and Ceratonia siliqua seed germ flour.

Seed germ of South American algarrobo (Prosopis species) and European carob (Ceratonia siliqua) contains nutritionally interesting proteins, lipids and phenolics. Using reversed phase-HPLC-diode array detector and nanoflow-HPLC coupled to tandem mass spectrometry (MS/MS), we comparatively characterized and semi-quantified flavonoids from germ of three Argentinean algarrobo (Prosopis alba, Prosopis nigra and Prosopis ruscifolia) and one European carob species. The patterns of glycosylated flavonoids were very similar each other, confirming the taxonomic parentage of the species and supporting their functional similarity on a molecular basis, in view of the use of seed germ flour (SGF) for food applications. The predominant phenolic compounds were apigenin 6,8-C-di-glycoside isomers, namely isoschaftoside and schaftoside, accounting for 3.22-5.18 and 0.41-0.72 mg/g SGF, respectively. C. siliqua germ contained relatively high amounts of further glycosilated derivatives of (iso)schaftoside, which occurred at a lower abundance in Prosopis. Apigenin 6,8-C-di-glycosides have been described as potent α-glucosidase inhibitors, suggesting that food preparations obtained with Prosopis spp. and C. siliqua SGF might contribute to modulate the digestion of carbohydrates in humans. CHEMICAL COMPOUNDS: Isoschaftoside (PubChem CID: 13644661); Schaftoside (PubChem CID: 442658); Vicenin-2 (PubChem CID: 442664); Isovitexin (PubChem CID: 162350).