Let me explain in simpler terms.
There are two kinds of sourdough starters: those which are spontaneous, say, whenever a substrate and water are mixed together; and then there are those that are maintained.
The difference between the two is obvious. The first would be similar to those species in situ (think: wolf, fox, dingo), while the other, via whatever process parameters are used, actively selects and modifies the species present (over time, you get specialisation, like Chihuahuas, Golden Retrievers, Huskies, and so on).
When flour and water is mixed, there are an abundant of organisms that actively contaminate it. The shift from a spontaneous microflora (that which is sort of just naturally present at first, from whatever source) to a "maintained" and "selected" microfloral culture generally involves three steps (for any basic fermentative process, too):
1. Presence of atypical fermentative microorganisms.
2. Growth and eventual dominance of microorganisms more frequently associated / typical with whatever fermentation is occurring, with a decrease in the atypical species.
3. Growth and eventual dominance of typical but more highly-evolved species to whatever fermentative process is being used.
In sourdoughs that are continuously maintained, the species from #3 become the dominant microflora while those from either #1 or #2 become the sub-dominant.
The pineapple-juice method presupposes that those organisms from the first step (Leuconostoc, etc.) are undesirable. They are not. They are generally recovered from sourdoughs in cooler climates as the sub-dominant microflora(Belgium, France, the Netherlands, etc.).
Here's a list of the LAB species that have permanently colonise the human intestinal tract: Lbs acidophilus, brevis, casei, crispatus, delbrueckii, fermentum, fructivorans, gasseri, paracasei, plantarum, rhamnosus, ruminis, sakei, salivarius, and vaginalis.
All of these are from the #2 category, and all have been recovered as dominant and/or sub-dominant organisms in wheat- and/or rye-based sourdoughs.
Only one species represents #3 for wheat- and/or rye-based sourdough fermentations: LB SF.
There are other truly undesirable species that occur in #1 (true entero-pathogens, etc.), but they will be outcompeted every time by all the above mentioned species in a continuously maintained sourdough.
So, here's what the pineapple juice method says: Let's skip #1 and go straight to #2 so as to rid ourselves of undesirable organisms. Problem is, some of those in #1 are, in fact, desirable, depending upon the process-parameters (maintenance conditions) chosen, and those from #1 that ARE truly dangerous will lose out in time, every time to those desirable organisms from #s 1 -3 in a continually fed system.
Those LABs from #2 create more flavour, better fermentative conditions, etc.; hence, why we select them.
Those from #2 are more acid-tolerant than the one species from #3. Wink et al. assume that adding pineapple juice will acidify the substrate and automatically bring about the presence of those from #2 while eliminating all those from #1. NOT TRUE. Many of the bad entero-pathogens will disappear, but many species she identified as "bad" can and do survive such acidified conditions.
The best way to establish those microflora from #2, instantly, is temperature. Two of those organisms, fermentum and plantarum, are also recovered from raw wheat and rye grains, so no cross-contamination from humans is necessary. All one needs is the raw flour that contains these organisms (basically EVERY rye and/or wheat flour ever tested in the world), water (necessary for life activity) and the right temperature. Outside of substrate, temperature is the most important processing condition to select for or against any of these species.
Adding a mixture of whole rye and/or wheat flour with an unusually high amount of water (most of these LAB are non-motile) PLUS the right temperature will instantly activate and guarantee the presence of plantarum and/or fermentum, which are two of the most desirable "secondary" microflora. They can out-compete ANYTHING above 37 / 35 degrees Celsius, respectively, including LB SF.
My method involves a Ziploc bag, water and grain; a large plastic container (like a cooler) that has a lid; then filling the container with 37-degree water (say from the bath-tub); and then dropping the baggie into the water for 12 - 24 hours, adding extra hot water to maintain a constant 37 degrees. The ensures #2 is established. Upon second refreshment, I switch to an inoculation percentage and temperature (32) more favourable to LB SF. I arrive at a stable culture using this method in 3 - 5 inoculations (under optimised conditions), which is sort of the magic number for completely changing and/or establishing ANY sourdough culture.
The third refreshment also takes place in a bag, and uses a temperature profile that establishes a considerable yeast presence (28 degrees).
The method was developed for home-bakers without access to immersion circulators (I own many). It's what David Chang calls "ghetto-vide."
Do you follow my logic?
The problem with Wink's "research" is that it misunderstands the way in which most of these desirable sourdough organisms out-compete undesirable (pathogenic) organisms. She assumes it's via pH conditions, but we know this simply isn't true (LB SF dominates at conditions much, much more alkaline than any other LAB). Acidification is only ONE variable for establishing a culture, but not THE, especially for an LB-SF-based culture.
E-mail me for more details.
Once I have a good internet connection, I'll do a step-by-step process with the exact amounts necessary to complete this.