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.

在2、7和20°C下储存120天的苹果甜菜根汁中，研究了储存条件对pH，总可溶性固体（Brix），颜色，甜菜碱（betacyanins和虾青素）和5-羟甲基糠醛变化的影响。 。结果表明，苹果甜菜根汁的质量受温度和储存时间的影响很大。储存时间和温度的增加导致明度（L *），黄度（b *），色相角，总色差（ΔE）的表观升高（P <0.05））和5-羟甲基糠醛。20°C时5-羟甲基糠醛的最大浓度达到14.97±0.03 mg / L; 但是，该浓度低于苹果汁中允许的最大浓度（20 mg / L）。总色差和5-羟甲基糠醛浓度的增加与β-花青素和虾青素的减少有关，这被强的反相关性所证实（r从-0.7991到-0.9813）。β-花青素和虾青素的降解均遵循一级动力学模型，并且与红色（a *）和色度呈正相关。甜菜色素降解的较高速率常数（k）（k≈0.0064–0.0285天^-1）与虾青素降解的速率常数（k≈0.0073-0.0471天^-1）相比，表明花青素的降解速度稍快。除pH和白利糖度外，所有监测到的特征在20°C时的变化均显着大于7和2°C（P <0.05）。因此，苹果甜菜根汁应在较低的温度下保存，以保持其可接受的质量。