Revalorization of Almond By-Products for the Design of Novel Functional Foods: An Updated Review

Abstract

The search for waste minimization and the valorization of by-products are key to good management and improved sustainability in the food industry. The great production of almonds, based on their high nutritional value as food, especially almond kernels, generates tons of waste yearly. The remaining parts (skin, shell, hulls, etc.) are still little explored, even though they have been used as fuel by burning or as livestock feed. The interest in these by-products has been increasing, as they possess beneficial properties, caused by the presence of different bioactive compounds, and can be used as promising sources of new ingredients for the food, cosmetic and pharmaceutical industry. Additionally, the use of almond by-products is being increasingly applied for the fortification of already-existing food products, but there are some limitations, including the presence of allergens and mycotoxins that harden their applicability. This review focuses on the extraction technologies applied to the valorization of almond by-products for the development of new value-added products that would contribute to the reduction of environmental impact and an improvement in the sustainability and competitiveness of the almond industry.

Almond Hull as a Functional Ingredient of Bread: Effects on Physico-Chemical, Nutritional, and Consumer Acceptability Properties

“…Acid detergent fibre varies from 20.6 to 35.2%, neutral detergent fibre from 10.0 to 15.0%, cellulose from 20.6 to 35.2%, and crude lignin ranges from 7.5 to 15.6% [2]. Generally, this byproduct is used as livestock feed or fuel material [2], but it is a rich source of triterpenoids (betulinic, urosolic, and oleanolic acids), flavonol glycosides, phenolic acids (caffeic, ferulic, p-coumaric, and synaptic acids), catechin, protocatechuic acid, vanillic acid, and other polyphenolic compounds; therefore, it may be an interesting source of natural antioxidants and other bioactive compounds [3][4][5][6][7]. The total polyphenolic content is comprised of between 35.9 and 166.7 mg GAE/g extract [4,6].…”

“…Generally, this byproduct is used as livestock feed or fuel material [2], but it is a rich source of triterpenoids (betulinic, urosolic, and oleanolic acids), flavonol glycosides, phenolic acids (caffeic, ferulic, p-coumaric, and synaptic acids), catechin, protocatechuic acid, vanillic acid, and other polyphenolic compounds; therefore, it may be an interesting source of natural antioxidants and other bioactive compounds [3][4][5][6][7]. The total polyphenolic content is comprised of between 35.9 and 166.7 mg GAE/g extract [4,6]. When incorporated into the diet, almond hulls (AHs) not only reduce colon cancer risk in rats, increase high-density lipoprotein cholesterol levels, and reduce LDL cholesterol levels in humans [4,6], but also reduce DNA scission and metal ion chelation activities [4,5].…”

“…The total polyphenolic content is comprised of between 35.9 and 166.7 mg GAE/g extract [4,6]. When incorporated into the diet, almond hulls (AHs) not only reduce colon cancer risk in rats, increase high-density lipoprotein cholesterol levels, and reduce LDL cholesterol levels in humans [4,6], but also reduce DNA scission and metal ion chelation activities [4,5].…”

“…Recently, AHs were incorporated into feedstocks for cow, hens, and edible larvae [4]. The obtained results showed that there are no effects on milk and egg composition quality, while for edible larvae there is an increase in weight, yield, and calcium content [4]. In addition, Takeoka and Dao [8] evaluated the use of AH as a natural source of sweetener concentrate and dietary fibre.…”

Valorization of Rose Hip (Rosa canina) Puree Co-Product in Enriched Corn Extrudates

“…Over the last decade, the emerging trends in food processing have been based on a few pillars, from which the design of health-promoting food and waste reduction is crucial [1,2]. Using this approach, the bio-functional molecules from different unused raw materials, or part of them, could be delivered to the human body, especially when innovative processing technologies are used [3].…”