title: Antioxidant and rheological properties of guava jam with added concentrated grape juice.
abstract: BACKGROUND
  Guava jam enriched by the addition of concentrated grape juice in the proportion of 30% (w/w) (ENR) was studied for its antioxidant potential and rheological behavior. Total phenolics content, 1,1-diphenyl-2-picrylhydrazyl radical (DPPH(•)) scavenging activity and β-carotene-linoleic acid coupled oxidation assays were used to evaluate the antioxidant properties of the samples during storage for 90 days at room temperature (25°C).
  
  
  RESULTS
  The ENR showed a total phenolic content of 11.09 g GAE kg(-1) of jam at production, more than two-fold the phenolic content presented by the standard formulation (STA). For the ENR formulation the antioxidant capacity increased in almost 20% (P ≤ 0.05) with time on the β-carotene assay and decreased with time on the DPPH assay. The enriched guava jam exhibited a non-Newtonian shear-thinning behavior at temperatures ranging from 25 to 55°C, and, moreover, presented higher stability than the standard formulation when exposed to temperature variation.
  
  
  CONCLUSIONS
  ENR constitutes an original food product with a notable antioxidant potential, even greater than the potential presented by the standard guava jam, worldwide appreciated delicacy.
authors.affiliation: Universidade Estadual de Maringá, Programa de Pós-Graduação em Ciência de Alimentos (PPC), Av. Colombo, 5790. CEP:, 87020-900, Maringá, PR, Brazil.
authors.forename: Rúbia C G
authors.initials: RC
authors.lastname: Corrêa
authors.forename: Charles W I
authors.initials: CW
authors.lastname: Haminiuk
authors.forename: Gisele T S
authors.initials: GT
authors.lastname: Sora
authors.forename: Rosangela
authors.initials: R
authors.lastname: Bergamasco
authors.forename: Angélica M S
authors.initials: AM
authors.lastname: Vieira
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D001713:Biphenyl Compounds / Q000737:chemistry; D055598:Chemical Phenomena; D005638:Fruit / Q000737:chemistry*; D055951:Functional Food / Q000032:analysis*; D019787:Linoleic Acid / Q000737:chemistry; D010084:Oxidation-Reduction; D010636:Phenols / Q000032:analysis; D010851:Picrates / Q000737:chemistry; D031647:Psidium; D012212:Rheology; D027843:Vitis; D019207:beta Carotene / Q000737:chemistry
chemical_list: D000975:Antioxidants; D001713:Biphenyl Compounds; D010636:Phenols; D010851:Picrates; D019207:beta Carotene; D019787:Linoleic Acid; C004931:1,1-diphenyl-2-picrylhydrazyl
keywords: antioxidant activity; food enrichment; fruits; functional food; phenolics; rheological behavior study