May one purchase juice without a Hashgacha?

A. Freshly squeezed juice stands:

One may purchase juice at a fruit stand without a Hashgacha so long as the following conditions are met:

1. One is not in Eretz Yisrael, and the fruits used have no reason to be assumed that they come from Eretz Yisrael.[1]
2. There are no powders or other additives without a Hashgacha placed into the juice and it is 100% pure juice, as witnessed by the Jewish buyer.
3. There are no grapes added to the ingredients of the juice.[2]
4. Sugar may be added.[3]
5. The fruits used for the shake are not required to be checked for insects, or one checks the fruit prior to its use.[4]
6. The knife being used to cut the fruit has been washed.
7. The machine used for the squeezing [both its blades and container] has been washed completely clean from any previous uses [which may have included grapes or grape juice or Chalav Akum milk].
8. Lemons: One should not add lemons to the ingredients being that lemons are considered a Davar Charif and can absorb taste from the blades of the knife.[5]

B. Bottled juices:

All processed juices, which refers to all juices that are factory made and packaged, even if they state 100% juice, must have a reliable Hashgacha in order to verify that non-Kosher ingredients have not been used in making the juice. The possible Kashrus issues involved with processed juices are:

1. Chalav Akum: Perhaps the machine line used for the juice contained remnants of non-Kosher milk. Likewise, perhaps the juice was pasteurized [heated] in a container that is also used to heat non-Kosher milk. [It is common for juicing factories to make various beverages on different days of the week, including milk beverages.]
2. Yayin Nesech: Perhaps the machine line used for the juice contained remnants of grape juice, which is Yayin Nesech. Likewise perhaps the juice was pasteurized [heated] in a container that is also used to heat grape juice. [It is common for juicing factories to make various beverages on different days of the week, including grape beverages.]
3. Insects: If the fruit requires checking for bugs, then this must be verified prior to squeezing.
4. Additives: Perhaps a non-Kosher additive, preservative, food coloring or some other sub-ingredient has been added to the drink. [Such additives do not legally prevent the writing of 100% pure juice if they are considered a mere trace ingredient.]

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[1] The reason: Fruits of Eretz Yisrael must be verified to not contain an Arla prohibition, likewise both fruits and vegetables must be tithed prior to eating.

[2] The reason: As this enters one into an issue of Yayin Nesech, if the juice maker is a gentile or is not a Shomer Shabbos Jew.

[3] Sugar does not need a Hashgacha.

[4] It is forbidden to grind fruits that require checking with exception to specific circumstances in which this is allowed: See Michaber 84/14; Shach 84/39-40; Taz 84/19-20; Darkei Teshuvah 84/165-169; Kaf Hachaim 84/131-134

[5] See Michaber/Rama 96/4; Shach 96/20