The effect of hazelnut roasted skin from different cultivars on the quality attributes, polyphenol content and texture of fresh egg pasta

By-product hazelnut seed skin characteristics and properties in terms of use in food processing and human nutrition

The hazelnut seed skins (HSS) are by-products from roasting or blanching hazelnuts without direct second utilization. The generation of HSS creates an economic and environmental problem. The object of the study was a comprehensive analysis of the properties for reuse of HSS. Water extraction of industrial HSS was applied (water with sonication of the HSS for 10 min at 90 ℃). The extracts obtained were freeze-dried to facilitate analysis and future application. The HSS and their extracts were analysed. Polyphenols, antioxidants, allergens, antimicrobial properties and instrumental sensory analysis were examined. The total polyphenol content in the samples was 37.8-44.0 mg gallic acid equivalent g-1. Gallic acid was the major phenolic compound. The antioxidant capacity of the samples was 198.9-250.6 mg VCEAC g-1 (vitamin C equivalent) according to the ABTS method and 98.4-106.8 mg VCEAC g-1 in the DPPH method. The extracts inhibited all tested strains of pathogenic bacteria. Allergen content was reduced in HSS and the extracts. Instrumental sensory analysis showed differences between taste parameters and odour profile samples. HSS can be reused in food production as a bacteriostatic, antioxidant additive and sensory-creating factor due to various chemical compounds corresponding with taste and odour.

Hazelnut Skin Waste as a Functional Ingredient to Nutritionally Improve a Classic Shortbread Cookie Recipe

Hazelnut skin (HS) is a byproduct of hazelnut processing (2.5% of total kernel) and becomes a food waste despite its high content of antioxidants, unsaturated fats, and fibers. Classic shortbread cookies have a large worldwide market, even if their nutritional composition does not meet nutritional guidelines due to the high content of saturated fats. In the present study, after the nutritional evaluation of four different HS varieties, 5% and 10% ratios of HS of the Tonda Gentile Romana variety were integrated into a classic shortbread cookie recipe, proportionally replacing the butter amount with the unsaturated fats naturally present in HS. The 10% HS addition determined a 20% increase in the monounsaturated oleic acid and a 15.7% decrease in the saturated palmitic acid, in addition to a significant ash increase. The sensory analysis revealed higher consumer acceptance of the 5% formulation, with scores comparable to the control. Although the 10% formulation obtained lower scores for consumer acceptance, 35% of the interviewed population said they would purchase it, indicating that this product, beyond the ethical dimension of using a food waste matrix to promote the circular economy, can attract the commercial interest of part of the population.

Sex-dependent colonic microbiota modulation by hazelnut (Corylus avellana L.) dietary fiber

Although many efforts have been made to characterize the functional properties of hazelnut constituents (mainly its oil, protein, and phenolics), those of its dietary fiber (DF) have not been elucidated yet. Here, we aimed to investigate the impact of DF of natural and roasted hazelnuts, and hazelnut skin on the colonic microbiota in vivo (C57BL/6J mouse models) by determining their composition through 16S rRNA sequencing and microbial short-chain fatty acids (SCFAs) using gas chromatography. Our results revealed that hazelnut DF generally showed an acetogenic effect in male mice, whereas the same trend was not observed in the female counterparts. The 16S rRNA sequencing results showed that hazelnut DF, especially that of natural hazelnuts, increased the relative abundances of Lactobacillus-related OTUs that have probiotic potential. LEfSe analysis indicated that, for female mice, Lachnospiraceae, Prevotella, Ruminococcaceae, and Lactobacillus were found to be discriminators for DF of natural hazelnuts, roasted hazelnuts, hazelnut skin, and control, respectively, whereas Bacteroides, Lactobacillus, Prevotella, and Lactococcus were the discriminators for the male counterparts, respectively. This study clearly indicates that, although the roasting process slightly alters the functionalities, hazelnut DF favors beneficial microbes and stimulates beneficial microbial metabolites in the colon in a sex-dependent way, which could be a contributing factor to the health-promoting effects of hazelnuts. Furthermore, hazelnut skin, a byproduct of the hazelnut industry, was found to have potential to be utilized to produce functional DF targeting colonic health.

Valorisation of hazelnut by-products: current applications and future potential

Hazelnut is one of the most widely consumed nuts around the world. Considering the nutritional value of hazelnuts, a wide range of hazelnut-based food products are available in the market such as oil, chocolate, confectionery, etc. Nevertheless, the processing of hazelnuts generates a large number of by-products and waste. The most valuable by-products of the hazelnut industry are shell, skin, and meal. These by-products are rich in bioactive compounds, protein, dietary fibre, mono- and polyunsaturated fatty acids, vitamins, minerals, phytosterols, and squalene. The current utilisation of hazelnut by-products is mostly limited to animal feed supplementation of hazelnut meal and skin and use as a low-value heat source for the shells. However, disposing of these by-products or using them as a low-value heat source or animal feed supplementation results in significant waste of a natural resource rich in nutritional components. Consequently, valorising hazelnut by-products as bioactive ingredients in diverse fields such as food, pharmaceuticals and cosmetics has stimulated interest among scientists, producers, and consumers. This review provides an overview of current scientific knowledge about the main and most valuable hazelnut by-products and their actual valorisation, with a focus on their chemical composition to inspire new applications of these valuable resources and fully exploit their potential.

Recovery and Concentration of Polyphenols from Roasted Hazelnut Skin Extract Using Macroporous Resins

Hazelnut skin is a rich source of polyphenols but is generally discarded during the roasting process of hazelnuts. Previous studies reported the extraction and identification of these compounds using different solvents and procedures; however, there are few reports on their enrichment and purification. In this study, three types of Amberlite macroporous resins (XAD 16, XAD 4, and XAD 7) were compared to evaluate the enrichment of polyphenols via adsorption and desorption mechanisms. The operating condition parameters for polyphenol adsorption/desorption of each resin were determined, the kinetics of adsorption were examined, and a method for polyphenol recovery was developed using static and dynamic adsorption/desorption. Antioxidant activity and high-performance liquid chromatography-diode array detection were used to confirm the increase in polyphenols obtained using the adsorption/desorption technique. XAD16 showed the highest adsorption capacity, with a recovery of 87.7%, and the adsorption kinetics fit well with a pseudo-second-order model. The highest poly-phenol desorption ratio was observed using an ethanol/water solution (70% v/v) at a flow rate of 1.5 bed volume/h.

The Influence of Hazelnut Skin Addition on Quality Properties and Antioxidant Activity of Functional Yogurt

There is an increasing interest in applying fruit-processing wastes as functional food ingredients. Hazelnut skin, an interesting and innovative ingredient has recently been evaluated as one of the richest edible sources of polyphenolic compounds. This study aimed to evaluate the use of hazelnut skin as a functional additive in yogurt and to determine the effect of various percentages (2%, 3%, and 4%) of hazelnut skin on the physicochemical, microbiological, rheological, biochemical, and sensorial properties of yogurt. The results showed that the addition of hazelnut skin significantly increased total solids from 16.5% to 17.7% and fat content from 3.45% to 4.60% and decreased titratable acidity by up to 36%. The enrichment with hazelnut skin also improved the viability of yogurt bacteria, water holding capacity (WHC), and antioxidant activity of yogurts. Better results for WHC and antioxidant values were found in yogurt enriched with 4% hazelnut skin. Total phenolic content and Fe²⁺ chelating activity of yogurts increased with the increasing hazelnut skin ratio. However, yogurts with hazelnut skin had low instrumental texture parameters and apparent viscosity values. On the other hand, acceptable sensorial properties similar to control yogurts increase the consumption potential of yogurts enriched with hazelnut skin.

Evaluating the Suitability of Hazelnut Skin as a Feed Ingredient in the Diet of Dairy Cows

Simple Summary

Agriculture is estimated to generate about 700 million tons of waste annually in the Eurpoean Union (EU). Most of the by-products derived from the agricultural industry become organic waste, thus resulting in the loss of valuable nutrients and bioactive compounds and causing environmental and economic issues. Increasing the efficiency of waste management is a major global challenge that must be met in order to minimize the abovementioned negative impacts. Some agro-industrial by-products can be valorized by their inclusion in feed formulations. Hazelnut skin is a by-product of the hazelnut industry. It is a good source of phenolic compounds, polysaccharides, unsaturated fatty acids, and vitamin E. In this study, we evaluated the productive performance of dairy cows in response to the inclusion of hazelnut skin in the diet. We observed no effects of hazelnut skin on either the milk production level or fat and protein contents. The oleic acid concentration in milk was strongly increased by including hazelnut skin in the cows’ diet. Improvements in the antioxidant activity and sustainability of milk production in terms of food–feed competition were also observed. These results are of practical application for feed manufacturers and farmers, as they support the inclusion of sustainable and low-cost feed ingredients in ruminant diets, with the aim of supporting the expected increase in livestock production in the upcoming years.

Abstract

Hazelnut skin (HS) was evaluated as a source of nutrients for dairy cows. In total, 26 Aosta Red Pied cows were divided into two balanced groups. All cows were fed hay ad libitum. The control group was also given 6 kg of concentrate, while the hazelnut skin group (HAZ) was given 1 kg of the same concentrate that was substituted by 1 kg of HS. The dry matter intake of the cows was reduced by the dietary inclusion of HS (p ≤ 0.001). The milk yield and main constituents were unaffected by treatment. Milk from HAZ cows showed decreased concentrations of de novo saturated fatty acids (FAs), odd- and branched-chain FA, α-linolenic acid, and long-chain n-3 FAs, as well as increased concentrations of stearic acid, oleic acid, linoleic acid, total monounsaturated FAs, trans biohydrogenation intermediates, and α–tocopherol. Replacing the concentrate with HS increased the human-inedible feed quota in the diet and improved the sustainability of milk production in terms of the food-feed competition. Our results suggest that it is possible to add economic value to organic waste from the hazelnut industry using HS as a feed ingredient for dairy cows, enhancing the feed efficiency and milk antioxidant activity and having expected impacts on the nutraceutical quality of milk fat.

Hazelnut as Ingredient in Dairy Sheep Diet: Effect on Sensory and Volatile Profile of Cheese

The opportunity of replacing expensive feedstuffs with agro-industrial by-products in the diet of food producing animals is raising increasing interest while addressing global concern for the scarcity of natural resources and environmental impact of livestock farming. Hazelnut peels, rich in fiber and vitamins and characterized by a high concentration of fats, is considered a suitable ingredient to be included in the diet of ruminants. The aim of this research was to assess the effect of dietary hazelnut peels on the chemical and sensory properties of sheep cheese during refrigerated storage. To this purpose, 20 Comisana lactating ewes were randomly assigned to two experimental groups, control (C) and hazelnut peels (HP), balanced for parity, milk yield and body weight. Bulk milk collected from the 2 groups was used to produce 5 Pecorino cheeses for each group. After 40 d of aging, each cheese of each experimental group was divided into 3 pieces: 1 piece was sampled for analyses (C0, HP0) and 2 were wrapped in PVC film, simulating the condition of pre-wrapped products, and analyzed after 7 (C7, HP7) and 14 days of storage (C14, HP14) at 8°C with 80% moisture. The cheeses were analyzed for chemical and fatty acid composition, sensory analysis, odor active compounds and SmartNose. As expected, HP cheeses presented a higher lipid content compared to C, a lower content in SFA and PUFA, and a greater content in MUFA. A triangle test revealed a clear distinction between the 2 groups (α = 0.01) The sensory profile showed a significant effect on holes (P < 0.05) and a marginal production of off-flavors linked to spicy and acid attributes for HP cheeses The volatile profile of C and HP cheese samples showed a good similarity, partially explained by the short ripening time and the absence of 2-nonanone in HP7, suggesting a higher antioxidant protection grade of this cheese compared to the others. These results were confirmed by Smart Nose analysis. Further studies on vitamin content should be conducted in order to investigate the interactions between the presence of antioxidant volatile compounds and the oxidative stability of ewe cheese.

Development of Health Products from Natural Sources

BioActive Compounds (BACs) recovered from food or food by-product matrices are useful in maintaining well being, enhancing human health, and modulating immune function to prevent or to treat chronic diseases. They are also generally seen by final consumers as safe, non-toxic and environment-friendly. Despite the complex process of production, chemical characterization, and assessment of health effects, BACs must also be manufactured in stable and bioactive ingredients to be used in pharmaceutical, food and nutraceutical industry. Generally, vegetable derivatives occur as sticky raw materials with pervasive smell and displeasing flavor. Also, they show critical water solubility and dramatic stability behavior over time, involving practical difficulties for industrial use. Therefore, the development of novel functional health products from natural sources requires the design of a suitable formulation to delivery BACs at the site of action, preserve stability during processing and storage, slow down the degradation processes, mask lousy tasting or smell, and increase the bioavailability, while maintaining the BACs functionality. The present review focuses on human health benefits, BACs composition, and innovative technologies or formulation approaches of natural ingredients from some selected foods and by-products from industrial food transformations.

Chemical modifications of Tonda Gentile Trilobata hazelnut and derived processing products under different infrared and hot-air roasting conditions: a combined analytical study

BACKGROUND

For the processing industry, it is crucial to know what effect the roasting process and conditions have on hazelnut quality. The present study investigates, for the first time, the effects of hot-air and infrared (IR) roasting at different time-temperature combinations on Tonda Gentile Trilobata hazelnut: whole kernels and derived processing products (paste and oil).

RESULTS

The nutritional and physical characteristics of hazelnuts and processing products were investigated to determine the influence of the different roasting conditions as a function of intended use. The antioxidant profile (2.2-diphenyl-1-picrylhydrazyl radical, oxygen radical absorbance capacity and total phenolic content) were analyzed on roasted hazelnut and paste extracts. For a comprehensive understanding of the complex biochemical phenomena occurring during roasting, E-nose and near-IR spectroscopy were also applied. All analytical data were processed using univariate and multivariate data analyses. Hazelnuts derived from IR roasting at higher temperatures (195 °C) showed a richer antioxidant profile and a more intense flavour. On the other hand, the yield associated with the oil extraction under the same conditions was unsatisfactory, making this process completely inadequate for oil production. Oil obtained by hot-air roasting and IR roasting at lower temperature (135 °C) was found to be of good quality, showing rather similar acidity grade, peroxide number and acidic composition. In particular, a slightly but significantly lower acidity was related to lower roasting temperatures (0.21-0.22% versus 0.27% for higher temperatures). All roasting conditions tested allowed the quantitative homogeneous hazelnut paste to be obtained and, from a rheological point of view, a higher roasting temperatures resulted in pastes characterized by higher density and viscosity values.

CONCLUSION

The use of IR was found to be a promising alternative method for hazelnut roasting, as a result of its capability with respect to preserving nutritional values and enhancing organoleptic quality. © 2018 Society of Chemical Industry.