Good Fruit Grower

September 2016

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48 SEPTEMBER 2016 Good Fruit Grower BSG wine acid test I n general, the wine acid test from BSG is cheaper to purchase than the Accuvin tube test. However, due to the additional equipment needs and the higher time requirement to perform the actual test, the overall operating costs are higher. Also, this test is not suitable for field use. Atago PAL-BX|ACID5 A tago's PAL-BX|ACID5 is able to measure the SSC and the TA one after another from the same juice sample. However, in order to be able to measure the TA content after the SSC measure- ment, a 1:50 dilution has to be made. This step can lead to calculation errors. Overall, the device showed an accuracy of about 78 percent. Felix F-750 T he F-750 allows the nondestructive mea- surement of certain parameters. However, a model has to be created for each parameter and each lot of fruit separately. During a proof of concept study, the WTFRC attempted to develop a firmness, DMC, TA, SSC and DA model for Fuji, Honeycrisp and Cosmic Crisp apples. Our results showed it was possible to create DA and dry matter models. However, no model could be created for firmness, SSC and TA with the current software. More specific research is required to see if there is a need to develop models for individual varieties, pre- and postharvest measurements and to work out specific recommendations for the measuring procedure. The device is not currently ready for field application. Accuvin Titratable Acidity Test Kit C urrently, the Accuvin acidity tube test is the fastest and easiest method to determine apple fruit acidity levels of all test kits evaluated by WTFRC to date. Due to its lower accuracy, this test should be used if gaining information about the acidity range is more important than an exact value, such as when trying to group lots of Honeycrisp apples based on high or low TA levels for different storage durations. We noted that this test requires minimum train- ing and can be performed in the field or at receiving. Summary W hile there was little progress in the commercial development of new devices to help growers and packers accurately, quickly and economically determine common maturity parameters, several options have become available in recent years. Some devices, such as the Accuvin Titratable Acidity Test Kit, should be able to be used successfully without any problem. Others, like the Felix F-750 are very promising, but will need further refinement in order to be easily adoptable for quality control personnel or others. • Metrohm Titrator T he Metrohm Titrator measures TA content. Due to its purchase price, it is useful in situations that require a high sample through- put (such as larger packing house operations or research stations). Also, the Metrohm requires systematic calibration and maintenance under lab conditions. Titration with the Metrohm is the standard method to measure the TA content of all experimental fruit at the WTFRC. The PREMIER Show for fruit and vegetable growers, greenhouse growers and farm marketers! 4,000 + attendees 75+ education sessions and workshops 450 + exhibitors

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