Abstract
Background: Walnuts (Juglans regia L.) are attracting increasing interest from consumers, industry, and the healthcare community due to their high content of bioactive compounds, including (poly)phenols, carotenoids, tocopherols, and omega-3 fatty acids. Despite the continued growth in global walnut production, the effective valorisation of walnut processing by-products remains a challenge. While most research has focused on the edible kernel, emerging evidence suggests that underutilized walnut fractions may also represent valuable sources of compounds with antioxidant and anti-inflammatory properties. This study aimed to characterize the bioactive compound profiles of green walnuts, defective walnuts, and walnut shells in comparison to commercial whole walnuts and kernels. Methods: Samples collected from an orchard located in Huesca (Spain) were homogenized and analysed in triplicate. Proximate composition was performed following the official methods, fatty acid profile was determined by GC-FID, phenolic profile by UHPLC-ESI-MS/MS, and carotenoids and tocopherols by UPLC-DAD. Results: Green walnuts contained exceptionally high concentrations of carotenoids, especially β-carotene (629.7 ± 39.4 mg/kg). Walnut shells were the richest source of phenolic compounds, notably ellagic acid (713.3 ± 7.6 mg/kg) and catechin (71.9 ± 1.2 mg/kg). Tocopherols were mainly concentrated in the kernel, dominated by γ-tocopherol (226.9 ± 8.1 mg/kg), while defective walnuts showed a compositional profile similar to commercial walnuts. Conclusions: This comparative analysis highlights the significant potential of walnut processing by-products as sources of nutritionally relevant bioactive compounds. The findings support their valorisation as functional ingredients for agro-food and cosmetic applications within a circular economy framework.
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Claims 7
Claim · model-written summary
Green walnuts contained exceptionally high concentrations of carotenoids, especially β-carotene at 629.7 ± 39.4 mg/kg.
- Taxon
- Juglans regia
Juglans regiat0 - Organ / stage
- Green walnutse0
- Outcome
- concentrations of carotenoidse0
- Value
- 629.7 ± 39.4 mg/kge0
- Qualifier
- exceptionally highe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“walnut (Juglans regia L.)”
e0“Green walnuts contained exceptionally high concentrations of carotenoids, especially β-carotene (629.7 ± 39.4 mg/kg)”
Claim · model-written summary
Walnut shells were the richest source of phenolic compounds among the walnut fractions analysed.
- Taxon
- Juglans regiaJuglans regiat0
- Organ / stage
- Walnut shellse0
- Outcome
- phenolic compoundse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“walnut (Juglans regia L.)”
e0“Walnut shells were the richest source of phenolic compounds”
Claim · model-written summary
Walnut shells contained ellagic acid at 713.3 ± 7.6 mg/kg.
- Taxon
- Juglans regiaJuglans regiat0
- Organ / stage
- Walnut shellse0
- Outcome
- ellagic acide1
- Value
- 713.3 ± 7.6 mg/kge1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“walnut (Juglans regia L.)”
e0“Walnut shells were the richest source of phenolic compounds”
e1“ellagic acid (713.3 ± 7.6 mg/kg)”
Claim · model-written summary
Walnut shells contained catechin at 71.9 ± 1.2 mg/kg.
- Taxon
- Juglans regiaJuglans regiat0
- Organ / stage
- Walnut shellse0
- Outcome
- catechine1
- Value
- 71.9 ± 1.2 mg/kge1
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“walnut (Juglans regia L.)”
e0“Walnut shells were the richest source of phenolic compounds”
e1“catechin (71.9 ± 1.2 mg/kg)”
Claim · model-written summary
Tocopherols were mainly concentrated in the walnut kernel, dominated by γ-tocopherol at 226.9 ± 8.1 mg/kg.
- Taxon
- Juglans regiaJuglans regiat0
- Organ / stage
- kernele0
- Outcome
- Tocopherolse0
- Value
- 226.9 ± 8.1 mg/kge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“walnut (Juglans regia L.)”
e0“Tocopherols were mainly concentrated in the kernel, dominated by γ-tocopherol (226.9 ± 8.1 mg/kg)”
Claim · model-written summary
Defective walnuts showed a compositional profile similar to commercial walnuts.
- Taxon
- Juglans regiaJuglans regiat0
- Material
- defective walnutse0
- Outcome
- compositional profilee0
- Comparator
- commercial walnutse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“walnut (Juglans regia L.)”
e0“defective walnuts showed a compositional profile similar to commercial walnuts”
Claim · model-written summary
The authors conclude that walnut processing by-products can be valorised as functional ingredients for agro-food and cosmetic applications.
- Taxon
- Juglans regiaJuglans regiat0
- Outcome
- valorisation as functional ingredients for agro-food and cosmetic applicationse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
t0“walnut (Juglans regia L.)”
e0“The findings support their valorisation as functional ingredients for agro-food and cosmetic applications”