Evaluation of qualitative changes of apple-beetroot juice during long-term storage at different temperatures

• Published in: Journal of food measurement & characterization Vol. 14; no. 6; pp. 3381 - 3388
• Main Authors: Tobolková, Blanka, Polovka, Martin, Daško, Ľubomír, Belajová, Elena, Durec, Ján
• Format: Journal Article
• Language: English
• Published: New York Springer US 01-12-2020; Springer Nature B.V
• Subjects: Apples; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Color; Degradation; Engineering; Food Science; Fruit juices; Hydroxymethylfurfural; Juices; Original Paper; pH effects; Rate constants; Storage; Storage conditions; Sugar beets; Temperature; Storage; Apple-beetroot juice quality; Betacyanins and betaxanthins; 5-hydroxymethylfurfural; Colour
• ISSN: 2193-4126; 2193-4134
• DOI: 10.1007/s11694-020-00592-0

The effect of storage conditions on changes of pH, total soluble solids (°Brix), colour, betalains (betacyanins and betaxanthins), and 5-hydroxymethylfurfural was investigated in apple-beetroot juices stored at 2, 7 and 20 °C for 120 days. The results obtained showed that the quality of apple-beetroot juice is significantly influenced by temperature and storage duration. Increasing storage time and temperature induced an apparent rise (P < 0.05) of lightness (
L*
), yellowness (
b*
),
hue angle
, total colour difference (
ΔE
) and 5-hydroxymethylfurfural. Maximal concentration of 5-hydroxymethylfurfural reached 14.97 ± 0.03 mg/L at 20 °C; however, this concentration is under the allowable maximal level in apple juice (20 mg/L). The increase in total colour difference and 5-hydroxymethylfurfural concentration was associated with a decrease of betacyanins and betaxanthins, confirmed by strong inverse correlations (
r
from − 0.7991 to − 0.9813). Degradation of both betacyanins and betaxanthins followed the first-order kinetic model and showed positive correlation with redness (
a*
) and
chroma
. Higher rate constants (
k
) for betacyanin degradation (k ≈ 0.0064–0.0285 day
−1
) in comparison with the rate constants for betaxanthin degradation (k ≈ 0.0073–0.0471 day
−1
) demonstrate that betacyanins degraded slightly faster. The changes in all monitored characteristics were significantly greater at 20 °C (P < 0.05) than at 7 and 2 °C, except pH and °Brix. Therefore, apple-beetroot juices should be stored at lower temperatures to maintain their acceptable quality.