Geschmack- und gesundheitsrelevante Qualität von ökologisch angbauten Äpfeln: Eine 3jährige Feldvergleichsstudie mit standard- und ganzheitlichen Untersuchungsmethoden

Summary

In a 3 years lasting field study with the ‘Golden Delicious’ cultivar, we compared fruits of 5 pairs of organic/integrated fruit farms. The orchards were similar in microclimate, soil conditions and planting system. To assess inner fruit quality we investigated at the beginning and at the end of cold storage: (i) standard parameters (firmness, sugar, malic acid., mineral content); (ii) sensorial quality by panel tests; (iii) health related components (23 phenolic compounds, nutritional fibres; vitamins); and (v) fruit «vitality quality» by holistic approaches (crystallisation in copper chloride, self degradation tests, feeding preference tests with laboratory rats).
The most significant differences were found in year one of the study, and were by tendency confirmed in the following two years. In year one all fruit samples of organic orchards had significantly firmer fruit flesh (14%), a 10 % higher index of inner quality (on basis of sugar and malic acid content and fruit flesh firmness), and 15% higher taste scores than conventional ones. Phosphorus content of the fruit flesh was 31% higher in organic apples and closely correlated (r2 = 0.93) with the index of inner quality and sensory score (r2 = 0.69). No extraction method of Phosphorus in the soil (water, NH4-EDTA, citric acid, CAL) correlated with the P-content in the fruits. However, P in the fruit flesh correlated by r2 = 0.72 with the microbial activity of the soil expressed as the ratio of microbialbound Nitrogen and Carbon in the soil. With a value of 3.85 the Cmic:Nmic ratio was 44.5 % lower (thus more favourable) in organic tree strips. Flavanols, with 65.7 % of the total polyphenol content were the dominant group of polyphenols. The content of flavonols was 22.7 % higher in organic apples
in the first year and 15.6 % in the average of the three years. The self-degradation test didn't provide significant differences. Laboratory rats, showed a tendency to prefer IP apples probably due to their advanced ripeness. Thus rat behaviour did not correspond with the sensory panel judgement.
The picture forming method provided a correct reproducibility with repeated blind samples before and after storage (r2 = 0.83), and distinguished 100 % correctly organic an IP fruit in the first year. In the second year there was one miss qualification. The average value over three dates of the index for «vitality quality», which was especially created for this study, was 44.6 % higher with organic apples The picture forming methods correlated well with sensory scores and standard quality (r2 = 0.63) in the first year. The study revealed interesting and consumer-relevant differences between organic and integrated apples with standard and holistic methods.