Is eating food with your bare hands more tasty?

Question

In India, it has been a tradition to eat food with (washed) bare hands instead of using a knife, fork, spoon or chopsticks. Family and relatives re-iterate that it's tastier to eat with bare hands.
Is this just a placebo effect or is there a scientific reason?

Some sources on the internet are this:

Indian mothers like to feed their babies by hand. And there is really nothing in the world as tasty as a ball of food fed to you at any age by your mother. Its composition is perfectly and instinctively calibrated by her fingers — a precise combination of rice and sambar, or stir-fried plantain and a couple flecks of papadom. And, of course, lots of ghee.

My mom once explained to my teenage self that the secret was biochemical: The subtle oils of her fingers imparted some sort of alchemy to the little sphere — a pheromonal cocktail, I suppose — that would only fully blossom in the mouth of her offspring. Others would just call it maternal love.

Then this:

First, there is a placebo effect. For the Westerner/outsider, eating with your fingers seems exotic. For (many, not all) South Asians, eating with your fingers brings back memories of family and comfort foods.

Second, your fingers are highly versatile and they are often the best implements for consuming these foods and blending together spices, condiments, and foodstuffs themselves. There is a reason why humans evolved fingers rather than forks.

Third, and how shall I put this? A lot of South Indian food is vegetarian and eating with your fingers adds flavors of…meat. The fleshy sort.

and this:

Eating with our hands, she says, makes us more aware of what we are eating, and keeps eating from being a mindless chore.

If we had to consider taste, I'd assume it's either:
1. The oils on our hand (too less to make a difference)
2. Or the salt/perspiration (too less to make a difference)
3. Or the dead skin cells that get rubbed off our palm (yuck, but this is just in humour)

Personally, I've not noticed any difference in taste, except that when putting rice+curry into ones mouth, one ends up tasting ones fingers, whereas in the other case, you end up tasting a metallic/wooden spoon/fork.

So is there any real justifiable reason to the claim of better taste?

p.s.: For example, cooking fish with kodampuli is said to end up with a different taste when cooked in an earthen pot, because the kodampuli is said to have chemicals that react with the pot and produce a unique taste which you won't get if cooked in an Aluminium vessel. Could there be some similar logic with eating food with bare hands?

Answer 1

There are scientific researches that say that touching (tactile sensations) itself, not just the changes in the diffusion of taste and odor compounds with different textures, can adjust the perception of taste and smell. The studies don't specifically say that the taste is always improved but tactile sensations affect the perceived taste.

There is also difference between the tactile sensation of the fingers and the tactile sensation of the mouth. I tried to include studies that specifically talks about touching with fingers.

Apart from the enjoyment that handling the food with our hands may provide to the eating experience, it is important to note that people can also evaluate a food’s texture (that is, they can gain useful information) using nothing more than haptic information. In one study, for example, Michael Barnett-Cowan [53] had blindfolded participants rate the freshness/staleness and the crispness/softness of a series of pretzels while biting into either the fresh or stale end of a pretzel. Barnett-Cowan manipulated the congruency between the tactile/haptic information provided to the participants’ hand and that provided to their mouth. In half of the trials, the participants were given a half fresh-half stale pretzel (incongruent conditions); whereas in the remainder of the trials, they were given either a whole fresh or stale pretzel (the congruent condition). The results revealed that in the incongruent conditions, the stale part of the pretzel was rated as being significantly fresher and crispier in-mouth because the hands held what felt like a fresh pretzel, and vice versa when holding the stale end. Such results suggest that the perceived texture of food in-mouth can be altered simply by changing the haptic information provided to the consumer’s hands (no matter whether those textural cues are delivered by the food being held in the hand or by the cutlery or plateware if that is held instead).

http://www.flavourjournal.com/content/2/1/14

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In our paper, we show that the evaluation of taste components can also be influenced by the tactile quality of the food. We first discuss how multisensory factors might influence taste, flavour and smell for both typical and atypical (synaesthetic) populations and we then present two empirical studies showing tactile-taste interactions in the general population.

Cross-modal tactile-taste interactions in food evaluations - http://www.ncbi.nlm.nih.gov/pubmed/26169315

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Taste is always accompanied by tactile stimulation, but little is known about how touch interacts with taste. One exception is evidence that taste can be “referred” to nearby tactile stimulation. It was recently found (Lim J, and Green BG. 2007. The psychophysical relationship between bitter taste and burning sensation: evidence of qualitative similarity. Chem Senses. 32:31–39) that spatial discrimination of taste was poorer for bitterness than for other tastes when the perceived intensities were matched. We hypothesized that this difference may have been caused by greater referral of bitterness by touch.

Tactile Interaction with Taste Localization: Influence of Gustatory Quality and Intensity - http://chemse.oxfordjournals.org/content/33/2/137.full

Additionally, multiple senses affect the perception of taste as mentioned in many studies. Here is another paper that reviews the impact of perceptual interactions on perceived flavor:

When eating or drinking, the individual experiences a multitude of sensations, including taste, smell, touch, temperature, sight, sound, and sometimes pain/irritation. This multi-faceted sensory experience is the underpinning of perceived flavor, although certainly some sensations contribute more than others.

http://www.sciencedirect.com/science/article/pii/S0950329303000417