Clean Label “Rocha” Pear (Pyrus communis L.) Snack Containing Juice By-Products and Euglena gracilis Microalgae

Abstract

“Rocha do Oeste” pear is a Portuguese Protected Designation of Origin variety and one of the country's most relevant fruits for its nutritional value, production area, and exportation amounts. The recent integration of a pilot-scale juice production line brought to SUMOL+COMPAL company the need to characterize the new resulting fractions and value the new by-products. The objective of this work was to value the juice clarification by-products, producing a clean label and fiber-rich snack, in a circular economy rationale, where the secondary products are upcycled back into the food value chain, by creating another food product that includes those by-products. For the above to be possible, the laboratory conditions to produce pear fractions were optimized. After optimizing the puree centrifugation, using response surface methodology (RSM), and optimizing the turbid juice crossflow filtration, the different fractions were characterized in rheological, nutritional, and physical aspects. Comparison to the pulps revealed an increase in the viscosity of the pomace; an enriching effect on the fructose, glucose, and dietary fiber levels in the pomace, and maintenance of the vitamin C levels after centrifugation; and with no effect on the contents of total phenols during the filtration step. A thick pear snack was developed, incorporating retained fraction, inulin, and Euglena gracilis in the pomace, and optimized regarding its firmness and dietary fiber content. The snack characterization revealed an interesting total phenols content (which was maintained from the raw materials). Compared to the snack without microalgae and a commercial fruit snack, the pear snack with E. gracilis was well-accepted by the sensory panel, mainly in texture and appearance, and can be further improved in aroma and flavor. The snack without microalgae was the favorite among the three samples, in most sensory parameters, and never got the answer “I'm sure I wouldn't buy it.” Therefore, an innovative, clean label and plant-based snack was developed, in a circular economy rationale, which was relatively well-appreciated by the panel. This snack is rich in dietary fiber, having the possibility of presenting various nutritional claims, and the potential for easy sensory optimization.

Upcycling Rocha do Oeste Pear Pomace as a Sustainable Food Ingredient: Composition, Rheological Behavior and Microstructure Alone and Combined with Yeast Protein Extract

“…Insoluble dietary fibers (IDF) are the largest fraction, contributing approximately to 61% of pomace dry weight, while soluble dietary fibers (SDF) represent 13.4%. This result is within the range obtained in the literature [4,5,11], indicating a larger proportion of insoluble dietary fibers in pear pomace, although higher than those reported for "Rocha" pear pomace [1]. The differences in these values may be related to the maturation stage of the harvest, but also due to the washing procedure applied to the pomace to remove simple sugars.…”

“…In this work, total phenolic content in pear pomace, analyzed by the Folin-Ciocalteau assay, was 3.9 mg CAE/g DW pomace (extractable + non-extractable phenolics), with free phenolics corresponding to 3.1 ± 0.2 mg CAE/g DW (Figure 1). This value was contained in the range of those presented in the literature [40] for different pear cultivars' pomaces, but slightly lower than that obtained for "Rocha" pear pomace [1]. This suggests that pomace pre-washing to remove small sugars, may have caused a loss in soluble phenolic compounds.…”

“…Rocha do Oeste Pear (Pyrus communis L.) is a Protected Designation of Origin (PDO) variety of pear and one of the most relevant fruits in Portugal. It is distinguished by its firmness, acidity, soluble solids content, color, as well as high digestibility, nutritional value, and high content of antioxidant phenolic compounds [1][2][3]. Pear juice pilot scale processing by SUMOL + COMPAL, an important Portuguese fruit juice company, encompasses a centrifugation process of the fruit puree, to produce a turbid juice.…”

“…Pear juice pilot scale processing by SUMOL + COMPAL, an important Portuguese fruit juice company, encompasses a centrifugation process of the fruit puree, to produce a turbid juice. Pulps centrifugation results in considerable amount of pomace (skins, seeds and flesh), mainly constituted of sugars, fibers, pectins, and other insoluble carbohydrates, minerals, organic acids and phenolic compounds [1]. Due to its composition, pear pomace may be applied as a cost-effective source of bioactive and functional compounds [2], as a food ingredient to control food texture and rheology behavior or be converted as a functional flour [4,5], thus upcycling food industry side streams.…”

“…Dietary fibers can also find a wide application in the food industry, holding high promise as a potential food additive and/or as a functional food ingredient due to their functional properties, including water-holding capacity, gel-forming, fat mimetic, texturizing, and thickening properties. Additionally, dietary fibers are regarded as one of the most effective ways to prevent and control chronic diseases caused by over-intake of fat, since they contribute to satiation, reduction of pre-prandial cholesterol and postprandial blood glucose levels [8], obesity control [9], digestive health [10], immunity response and intestinal mucosa integrity [1]. Total dietary fiber content in pear pomace from different cultivars was found to be significantly high, varying from 44 to 79% on a dry weight basis [4,5,11], with insoluble dietary fibers isolated from pear pomace, preventing high-fat diet-induced obesity in rats mainly by improving the structure of the gut microbiota [12].…”